Research ArticleGrid Connected Solar PV System with SEPIC ConverterCompared with Parallel Boost Converter Based MPPT

T Ajith Bosco Raj1 R Ramesh1 J R Maglin1 M Vaigundamoorthi1

I William Christopher1 C Gopinath1 and C Yaashuwanth2

1 Department of Electrical and Electronics Engineering Anna University Chennai 600 025 India2Department of Computer Science Engineering SRM University Tamil Nadu 603 203 India

Correspondence should be addressed to T Ajith Bosco Raj ajithboscorajgmailcom and R Ramesh rrameshannaunivedu

Received 22 August 2013 Revised 13 January 2014 Accepted 14 January 2014 Published 3 March 2014

Academic Editor Ismail H Altas

Copyright copy 2014 T Ajith Bosco Raj et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited

The main objective of this work is to study the behaviour of the solar PV systems and model the efficient Grid-connected solarpower systemThe DC-DCMPPT circuit using chaotic pulse width modulation has been designed to track maximum power fromsolar PV module The conversion efficiency of the proposed MPPT system is increased when CPWM is used as a control schemeThis paper also proposes a simplifiedmultilevel (seven level) inverter for a grid-connected photovoltaic systemThe primary goal ofthese systems is to increase the energy injected to the grid by keeping track of the maximum power point of the panel by reducingthe switching frequency and by providing high reliability The maximum power has been tracked experimentally It is comparedwith parallel boost converter Also this model is based on mathematical equations and is described through an equivalent circuitincluding a PV source with MPPT a diode a series resistor a shunt resistor and dual boost converter with active snubber circuitThis model can extract PV power and boost by using dual boost converter with active snubber By using this method the overallsystem efficiency is improved thereby reducing the switching losses and cost

1 Introduction

Because of constantly growing energy demand grid-con-nected photovoltaic (PV) systems are becoming more andmore popular and many countries have permitted encour-aged and even funded distributed-power-generation sys-tems Currently solar panels are not very efficient with onlyabout 12ndash20 efficiency in their ability to convert sunlight toelectrical power The efficiency can drop further due to otherfactors such as solar panel temperature and load conditionsIn order to maximize the power derived from the solar panelit is important to operate the panel at its optimal powerpoint To achieve this a maximum power point tracker willbe designed and implemented

TheMATLABPSPICE model of the PVmodule is devel-oped [1ndash4] to study the effect of temperature and insolationon the performance of the PVmoduleThe power electronicsinterface connected between a solar panel and a load orbattery bus is a pulse width modulated (PWM) DC-DCconverter or their derived circuits used to extract maximum

power from solar PV panel 119868-119881 characteristic curve ofphotovoltaic generators based on various DC-DC converters[5ndash8] was proposed and concluded that SEPIC converter isthe best alternative to track maximum power from PV panelThe various types of nonisolated DC-DC converters for thephoto voltaic system is reviewed [9]

The maximum power tracking for PV panel using DC-DC converter is developed [10] without using microcontrol-ler This approach ensures maximum power transfer underall atmospheric conditions The analogue chaotic PWM isused to reduce the EMI in boost converter The conversionefficiency is increased when CPWM is used as a controltechnique [11ndash13] To increase conversion efficiency an activeclamp circuit is introduced into the proposed one to providesoft switching features to reduce switching losses Moreoverswitches in the converter and active clamp circuit are inte-grated with a synchronous switching technique to reduce cir-cuit complexity and component counts resulting in a lowercost and smaller volume [14]

Hindawi Publishing CorporationInternational Journal of PhotoenergyVolume 2014 Article ID 385720 12 pageshttpdxdoiorg1011552014385720

2 International Journal of Photoenergy

Multilevel inverter consists of an array of power semi-conductor switches capacitor voltage sources and clampingdiodes The multilevel inverter produces the stepped voltagewaveforms with less distortion less switching frequencyhigher efficiency lower voltage devices and better electro-magnetic compatibility [15] The commutation (process ofturn off) of the switches permits the addition of the capacitorvoltages which reach high voltages at the output [16]

A modular grid-connected PV generation system pre-sents an actual behavioural model of a grid tied PV systemsuitable for system level investigations Simplified means formodelling the PV array and investigating a gradient basedMPPT into a very simple averaged model of the power con-verter was developed and themodel has been experimentallyvetted [17 18] A single-phase grid-connected inverter whichis usually used for residential or low-power applications ofpower ranges that are less than 10 kW [15] Types of single-phase grid-connected inverters have been investigated [19]A common topology of this inverter is full-bridge three-levelThe three-level inverter can satisfy specifications through itsvery high switching but it could also unfortunately increaseswitching losses acoustic noise and level of interference toother equipment Improving its output waveform reduces itsharmonic content and hence also the size of the filter usedand the level of electromagnetic interference (EMI) generatedby the inverterrsquos switching operation [20]

MATLAB-based modelling and simulation schemewhich is suitable for studying the 119868-119881 and 119875-119881 characteristicsof a PV array under a nonuniform insolation due to partialshading [21] was proposed The mathematical model of solarPV module is useful for the computer simulation The powerelectronics interface connected between a solar panel anda load or battery bus is a pulse width modulated (PWM)DC-DC converter or their derived circuits used to extractmaximum power from solar PV panel [22] The main draw-back of PV systems is that the output voltage of PV panels ishighly dependent on solar irradiance and ambient temper-ature Therefore PV panels outputs cannot connect directlyto the load To improve this a DC-DC boost converter isrequired to interface between PV panels and loads [23] Theboost converter is fixing the output voltage of the PV systemConverter receives the variable input voltage which is theoutput of PV panels and gives up constant output voltageacross its output capacitors where the loads can be connectedIn general a DC-DC boost converter operates at a certainduty cycle In this case the output voltage depends on thatduty cycle If the input voltage is changed while the duty cycleis kept constant the output voltage will vary Duty cycle isvaried by using a pulse width modulation (PWM) technique[24]

Silicon carbide (SiC) represents an advance in silicontechnology because it allows a larger energy gap SiC is classi-fied as a wide-band-gap (WBG) material and it is the main-stream material for power semiconductors [25 26] Amongthe different types of power semiconductors the power diodewas the best device to adopt SiC technologyThemain advan-tage of SiC is high-breakdown voltage and reverse-recoverycurrent is small [27ndash29] As a result higher efficiency andhigher power density can be brought to power electronic

Rp

RsID

DIsc

IPV

VPV

Figure 1 Equivalent circuit of solar PV module

systems in different applications [30 31] In this researcha new active snubber circuit is proposed to contrive a newfamily of PWM converters This proposed circuit providesperfectly ZVT turn on andZCT turn off together for themainswitch of a converter by using only one quasiresonant circuitwithout an important increase in the cost and complexityof the converter This paper proposes to implement ChaoticPWM as a control method to improve the steady state perfor-mance of the DC-DC SEPIC converter based MPPT systemfor solar PV module The nominal duty cycle of the mainswitch of DC-DC SEPIC converter is adjusted so that thesolar panel output impedance is equal to the input resistanceof the DC-DC converter which results in better spectralperformance in the tracked voltages when compared toconventional PWM control The conversion efficiency of theproposed MPPT system is increased when CPWM is usedthiswill be comparedwith parallel boost converterMultilevelinverters are promising as they have nearly sinusoidal output-voltage waveforms output current with better harmonicprofile less stressing of electronic components owing todecreased voltages switching losses that are lower than thoseof conventional two-level inverters a smaller filter size andlower EMI all of whichmake them cheaper lighter andmorecompact [29]

2 MATLAB Model of L1235-37WSolar PV Module

The output characteristics of the solar PVmodule depend onthe irradiance and the operating temperature of the cell Theequivalent circuit of PV module is shown in Figure 1

From Figure 1 the current and voltage equation is givenby

119868sc = 119868119863

+ 119868PV + (119881119863

119877119901

)

119881PV = 119881119863

minus (119868PV lowast 119877119904)

(1)

where diode current is 119868119863

= 119868119900

+ (119890(119881119863119881119879) minus 1)

Based on the electrical equation (1) and the solar PVmod-ule are modelled in MATLAB as shown in Figure 2 whichis used to enhance the understanding and predict the 119881-119868characteristics and to analyze the effect of temperature andirradiation variation If irradiance increases the fluctuationof the open-circuit voltage is very small But the short circuit

International Journal of Photoenergy 3

1000

Insolation

InsolationProduct

Voltage-current characteristics

Power-current characteristics

PV1

PV module (I)

IPV

IPV VPV

VPV

IPV ramp

PPV

PPV

PPV

Figure 2 MATLAB model for PV module

Figure 3 L1235-37W solar module under test

current has sharp fluctuations with respect to irradianceHowever for a rising operating temperature the open-circuitvoltage is decreased in a nonlinear fashion [4]

The 119881-119868 characteristics are validated experimentally inthe L1235-37Wp solar module as shown in Figure 3 Thetechnical specifications of L1235-37Wp solar module undertest are given inTable 1 Figure 4 shows the119881-119868 characteristicsof L1235-37Wp which is based on the experimental resultsunder irradiation (119866) = 1000Wm2 and temperature = 25∘C

21 Space Modelling of SEPIC Converter Input at MPP Therelation between input and output currents and voltage aregiven by

119881OUT119881IN

=119863

(1 minus 119863)

119868IN119868OUT

=119863

(1 minus 119863)

(2)

The duty cycle of the SEPIC converter under continuousconduction mode is given by

119863 =119881OUT + 119881

119863

119881IN + 119881OUT + 119881119863

(3)

Table 1 Specifications of L1235-37W solar PV panel

Short circuit current (119868sc) 25 AVoltage at MPP (119881

119898) 164

Current at MPP (119868119898) 225

Open circuit voltage (119881oc) 21 VLength 645mmWidth 530mmDepth 34mmWeight 4 kgMaximum power (119875max) 37W

3

25

2

15

1

05

00 5 10 15 20 25

Am

ps (A

)

Voltage (V)

MPP

Figure 4 119881-119868 characteristics of L 1235-37W solar panel

119881119863is the forward voltage drop across the diode (119863) The

maximum duty cycle is

119863max =119881OUT + 119881

119863

119881IN(MIN) + 119881OUT + 119881119863

(4)

The value of the inductor is selected based on the belowequations

1198711

= 1198712

= 119871 =119881IN(MIN) lowast 119863max

Δ119868119871

lowast 119891119878

(5)

4 International Journal of Photoenergy

Δ119868119871is the peak-to-peak ripple current at the minimum input

voltage and 119891119878is the switching frequency The value of 119862

1

depends on RMS current which is given by

1198681198621(RMS) = 119868OUT lowast radic

119881OUT + 119881119863

119881IN(MIN) (6)

The voltage rating of capacitor 1198621must be greater than the

input voltage The ripple voltage on 1198621is given by

Δ1198811198621

=119868(OUT) lowast 119863max

1198621

lowast 119891119878

(7)

The parameters governing the selection of the MOSFET arethe minimum threshold voltage 119881th(min) the on-resistance119877DS(ON) gate-drain charge 119876GD and the maximum drain tosource voltage 119881DS(max) The peak switch voltage is equal to119881IN + 119881OUT The peak switch current is given by

1198681198761(Peak) = 119868

1198711(PEAK) + 1198681198712(PEAK) (8)

The RMS current is given by

1198681198761(RMS) = 119868OUTradic(119881OUT + 119881IN(MIN)) lowast

119881OUT119881IN(MIN)2

(9)

The total power dissipation for MOSFETs includes conduc-tion loss (as shown in the first termof the above equation) andswitching loss (as shown in the second term) 119868

119866is the gate

drive current The 119877DS(ON) value should be selected at max-imum operating junction temperature and is typically givenin the MOSFET datasheet

119875switch = (1198681198761(RMS) lowast 119877DS(ON) lowast 119863MAX)

+ (119881IN(MIN) + 119881OUT) lowast 1198681198761(Peak) lowast

(119876GD lowast 119891119878)

119868119866

(10)

The output diode must be selected to handle the peak currentand the reverse voltage In a SEPIC converter the diode peakcurrent is the same as the switch peak current 119868

1198761(Peak) Theminimum peak reverse voltage the diode must withstand is

119881RD = 119881IN(MAX) + 119881OUT(MAX) (11)

22 Dynamic Input Characteristics of a SEPIC Converter atMPP The input voltage and the equivalent input resistanceof the converter are 119881

119878and 119877

119894 respectively As the input

power 120588119894to the converter is equal to the output power 120588

119900of

the solar PV module

120588119894= 120588119900

=1198812

119878

119877119894

(12)

The rate of change 120588119894with respect to 119881

119878and 119877

119894can be

shown below

120597120588119894=

2119881119878

119877119894

120597119881119878

minus1198812

119878

1198772

119894

120597119877119894 (13)

At the MPP the rate of change of 120588119894equals zero and 119877

119894=

119903119892

120597120588119894= 0 hence

120597119881119878

120597119877119894

=119881119878

2119877119894

(14)

The equation gives the required dynamic resistance char-acteristics of the tracker at MPP

23 Generation of Chaotic PWM In order to improve thesteady state performance of solar powered system direct con-trol Chaotic Pulse width modulated (CPWM) SEPIC con-verter is proposed to track maximum power from solar PVmodule Therefore in order to get chaotic frequency 119891

Δor

chaotic amplitude 119860Δ chaos-based PWM (CPWM) is ana-

lyzed to generate chaotic PWM The MATLAB simulation iscarried out as shown in Figure 5The analogue chaotic PWMhas its advantages over the digital in its low costs and easy-to-design making it suitable for high-frequency operation andsituations when design flexibility high converter conversionefficiency and low cost In order to generate chaotic pulsewidth modulation Chuarsquos diode is used to trigger the mainswitch of SEPIC converter and to be used for reducingspectral peaks in tracked converter voltage

The CPWM adopts sawtooth to modulate but its carrierperiod 119879

1015840

Δchanges according to

1198791015840

Δ=

119883119894

Mean (119909)lowast 119879Δ (15)

where 119879Δis invariant period 119883

119894 119894 = 1 2 119873 a chaotic

sequence 119909 = (1199091 1199092

119909119873

) and Mean(119909) average of thesequence defined as

Mean (119909) = Lim119873

sum

119894=1

10038161003816100381610038161198831198941003816100381610038161003816

1

119873 119873 997888rarr infin (16)

Similarly the CPWM also adopts sawtooth to modulate butits carrier amplitude 119860

1015840

Δchanges according to

1198601015840

Δ= 1 + 119870

119883119894

Mean (119909) 119860Δ (17)

where 119860Δis the invariant amplitude 119883

119894 119894 = 1 2 119873 a

chaotic sequence 119909 = (1199091 1199092

119909119873

) andMean(119909) average ofthe sequence and119870 is themodulation factor of the amplitudewhich can be set required in practice The value of 119870 isselected as low so that the ripple in the output voltage of theSEPIC converter is low Also the ripple in the output voltagecontrolled by chaotic PWM is lowThe analog chaotic carrieris generated based on the circuit the resistances (119877

1198891sdot sdot sdot 1198771198896

)

are used to realise linear resistor called Chua diodeThe para-meters for Chuarsquos diode are designed and chosen as 119877

1198891=

24 kΩ 1198771198892

= 33 kΩ 1198771198893

= 1198771198894

= 220 Ω and 1198771198895

= 1198771198896

=

20 kΩ The other parameters of Chuarsquos oscillator used in theexperiment are 119871

1= 22mH 119862

1= 47 nF 119862

2= 500 pF and

119877 = 175KΩ

International Journal of Photoenergy 5

Reset

Relational

Randomnumber

Discrete-time

Chaotic PWM

Chaos carrier

integrator1

A1

1z

operator1

Unit delay1

03ge

ge

Constant2

K Ts

z minus 1

Figure 5 Chaotic PWM pulse generation

Figure 6 Hardware setup

Figure 7 Chaotic PWM

24 Experimental Setup Standalone PV System Figure 6shows the experimental setup of the proposed SEPICconverter-based MPPT for solar PV module which is con-stituted by a power stage and a control circuit The powerstage includes an inductor 119871

1 1198712 capacitor 119862

1 1198622 a switch

119878 a load resistance and a solar PV module (L1235-37Wp)The analog chaotic carrier is generated based on the hardwareoutput of CPWM is in Figure 7

3 Mathematical Model for Parallel BoostConverter with Active Snubber Circuit

Figure 12 represents the circuit diagram of the parallel boostconverter with active snubber It consists of five inductors119871119891119894 1198711198912 1198711198771 1198711198772 119871119899and three capacitors 119862

119904 119862119903 119862119900 119881119892

and 119881119900represents supply and output voltage respectively

119878 (1198781 1198782) is an active primary switch 119863 (119863

1198911 1198631198912

) is a free-wheeling diode 119863

119904(1198631 1198632 1198633) is a Snubber diode and 119877

119871

is the load resistance 119878 (1198781 1198782 1198783) operates at a switching fre-

quency 119891119878with duty ratio 119889

Choose the switching frequency of switches 1198781

= 1198782

=

100KHz and 1198783

= 200KHzWhen 119878

1= 1198782

= 0 and 1198783

= 1 as in Figure 8

119889119894119871119865

119889119905=

1

119871119865

[119881119892

= 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

minus 119894119871119878]

(18)

Also the switches 1198781

= 1198782

= 1198783

= 1 as in Figure 9

119889119894119871119865

119889119905=

1

119871119865

[119881119892

minus 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

]

(19)

Similarly the switches 1198781

= 1198782

= 1 and 1198783

= 1 or 0 as inFigure 10

119889119894119871119865

119889119905=

119881119892

119871119865

119889119881119900

119889119905=

1

119862119900

[minus119881119900

119877119871

]

(20)

6 International Journal of Photoenergy

Vg

minus

+

Lf1

Lf2

Co RLLs Vo

iLs

iLf

Figure 8 When 1198781

= 1198782

= 0 and 1198783

= 1

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 9 When 1198781

= 1198782

= 1198783

= 1

By using state-space averagingmethod the state equationsduring switch-on and switch-off conditions are

1

=minus (1 minus 119889

1)

119871119865

1199092

minus(1 minus 119889

2)

119871119865

1199092

+

119881119892

119871119865

2

=minus1

119877119871119862119900

1199092

+(1 minus 119889

1) 1198892

119862119900

1199091

+(1 minus 119889

1) (1 minus 119889

2)

119862119900

1199091

(21)

where 1199091and 119909

2are the moving averages of 119894

119871119865and 119881

119900

respectively

4 Proposed Parallel Boost Converter forPV Application

Figure 11 shows the BlockDiagram of PV based parallel boostconverter with active snubber It is the combination of newactive snubber circuit with parallel boost converter Threeswitches 119878

1 1198782 and 119878

3are used 119878

1and 1198782act as main switch

and 1198783acts as an auxiliary switch 119878

1and 1198782are controlled by

ZVT and ZCT respectively also 1198783is controlled by ZCSThis

circuit operates with the input of solar powerAssume both the main switches (119878

1and 119878

2) operate in

the same frequency The features of proposed parallel boostconverter are as follows

(i) All the semiconductors work with soft switching inthe proposed converter

(ii) The main switches 1198781and 119878

2turn on with ZVT and

turn off with ZCT(iii) The secondary switch is turned on with ZCS and

turned off with ZCS

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 10 When 1198781

= 1198782

= 1 and 1198783

= 1 or 0

(iv) All other components of the parallel boost converterfunctions based on this soft switching

(v) There is no additional current or voltage force on themain switches 119878

1and 1198782

(vi) There is no additional current or voltage force on thesecondary switch 119878

3

(vii) Also there is no additional current or voltage force onthe main diodes 119863

1198911and 119863

1198912

(viii) According to the ratio of the transformer a part of theresonant current is transferred to the output loadwiththe coupling inductance So there is less current stresson the secondary switch with satisfied points

(ix) At resistive load condition in the ZVT process themain switches voltage falls to zero earlier due todecreased interval time and that does not make aproblem in the ZVT process for the main switch

(x) At resistive load condition in the ZCT process themain switches body diode on state time is increasedwhen the input current is decreased However thereis no effect on the main switch turn off process withZCT

(xi) This parallel boost converter operates in high-switch-ing frequency

(xii) This converter easily controls because the main andthe auxiliary switches are connected with commonground

(xiii) Themost attractive feature of this proposed converteris using ZVT and ZCT technique

(xiv) The proposed new active snubber circuit is easilyadopted with other basic PWM converters and alsoswitching converters

(xv) Additional passive snubber circuits are not necessaryfor this proposed converter

(xvi) SIC (silicon carbide) is used in the main and auxiliarydiodes so reverse recovery problem does not arise

(xvii) Theproposed active snubber circuit is also suitable forother DC-DC converters

41 Procedure for Constructing a Proposed Converter Steps toobtain a system level modeling and simulation of proposedpower electronic converter are listed below

International Journal of Photoenergy 7

Active snubber

Main diodesMain inductors MLI

Grid

Main capacitorMPPTSolar PV

Main switches

Snubber circuit

Auxiliary

Input source

(Lf1 Lf2)

Parallel boost converter

(S1 S2)

(L1235)

switch (S3)

Figure 11 Block diagram of PV based parallel boost converter with active snubber

Table 2 Specification of parallel boost converter with activeSnubber

Main inductor 1198711198911

750 120583HMain inductor 119871

1198912750 120583H

Upper Snubber inductor 1198711198771

5 120583HLower Snubber inductor 119871

1198772(119871119898

+ 119871119889) 2 120583H

Magnetization inductor 119871119872(119871119899

+ 1198710119897) 3 120583H

Parasitic capacitor 119862119904

1 120583FSnubber capacitor 119862

11987747 nF

Output capacitor 119862119900

330 120583F450VOutput load resistance 119877 = 119877

119871530Ω

(i) Determine the state variables of the proposed powercircuit in order to write its switched state-spacemodel for example inductance current and capaci-tance voltage

(ii) Assign integer variables (ON-1 and OFF-0 state) tothe proposed power semiconductor to each switchingcircuit

(iii) Determine the conditions controlling the states ofthe proposed power semiconductors or the switchingcircuit

(iv) Assume the main operating modes apply Kirchhoff rsquosCurrent law and Kirchhoff rsquos Voltage law and combineall the required stages into a switched state-spacemodel which is the desired system-level of the pro-posed model

(v) Implement the derived equations with MATLABSimulink

(vi) Use the obtained switched space-state model todesign linear or nonlinear controllers for the pro-posed power converter

The algorithm for solving the differential equations andthe step size should be chosen before running any simulationThis step is only suitable in closed-loop simulations [21]

42 Operation of Proposed Boost Converter with Snubber Cir-cuit Theproposed PV based converter is shown in Figure 12and it is based on a dual boost circuit where the first one(switch 119878

1and choke 119871

1198911) is used asmain chock of boost con-

verter circuit and where the second one (switch 1198782and choke

1198711198912) is used to perform an active filtering The proposed

converter applies active snubber circuit for soft switchingThis snubber circuit is built on the ZVT turn on andZCT turnoff processes of the main switches Specification of proposedparallel boost converter with active snubber is in Table 2

The power from the solar flows through the two parallelpaths High efficiency was obtained by this method So asto reach soft switching (SS) for the main and the auxiliaryswitches main switches turn on with ZVT and turn off withZCT The proposed converter utilizes active snubber circuitfor SS This snubber circuit is mostly based on the ZVT turnon and ZCT turn off processes of the main switch 119871

1198772value

is limited with (119881out1198711198772

)119905rise1198782 le 119868119894max to conduct maximum

input current at the end of the auxiliary switch rise time(119905rise1198782) and119871

1198771ge 21198711198772 To turn off 119878

1with ZCT the duration

of 119905ZCT is at least longer than fall time of 1198781(119905fall1198781)119905ZCT ge

119905fall1198781 Though the main switches are in off state the controlsignal is functional to the auxiliary switch The parasiticcapacitor of the main switch should be discharged absolutelyand themain switches antiparallel diode should be turned onThe on state time of the antiparallel diode is named 119905ZVT andin this time period the gate signal of the main switch wouldbe applied So the main switch is turned on below ZVS andZCS with ZVT

Whereas the main switches are in on state and ways inputcurrent the control signal of the auxiliary switch is appliedAfter the resonant starts the resonant current should behigher than the input current to turn on the antiparallel diodeof the main switchThe on state time of the antiparallel diode(119905ZCT) has to be longer than the main switches fall time (119905

1198911198781)

After all these terms are completed while antiparallel diodeis in on state the gate signal of the main switch should becutoff to provide ZCT for the main switch Auxiliary switchturn on with ZCS and turn off with ZCSThe auxiliary switchis turned on with ZCS for the coupling inductance limits thecurrent rise speed

8 International Journal of Photoenergy

Lf1

Lf2

S1 S2

S3

D2

Ld

Lm

LR1

D1

Ln

RLoad

Co

Lo1 D4

Df1

Df2

D3

CR

PVArray

Figure 12 Circuit diagram of PV based parallel boost converter with active snubber with resistive load

The current passing through the coupling inductancemust be partial to conductmaximum input current at the endof the auxiliary switch rise time (119905

1199031198783) So the turn on process

of the auxiliary switch with ZCS is offered To turn off theauxiliary switch with ZCS though the auxiliary switch is inon state the current passing through the switch should fallto zero with a new resonant Then the control signal can becutoff If 119862

119878is ignored 119871

1198771value should be two times added

with 1198711198772

to make the auxiliary switch current fall to zero Asthe current cannot stay at zero as long as the auxiliary switchfall time (119905

1198911198783) the auxiliary switch is turned off nearly with

ZCSThe proposed Simulink topology is shown in Figure 13

The inductors 1198711198911

and 1198711198912

have the similar values the diodes1198631198911-1198631198912

are at the same type and the same guess was for theswitches (119878

1amp 1198782) All the inductors have individual switches

and they resemble paralleling of classic converters

5 Design of MLI Module

A multilevel converter is a power electronic system thatsynthesizes a desired output voltage levels from theDC inputssupply Compared with the traditional two-level voltageconverter the primary advantage of multilevel converters istheir smaller output voltage step which results in high powerquality lower harmonic components better electromagneticcompatibility and lower switching losses The functionalityverification of the simplified seven-level inverter is doneusing MATLAB simulation which is shown in Figure 14

This single-phase simplified seven-level inverter wasdeveloped using a single-phase full bridge (H-bridge)inverter two bidirectional auxiliary switches and a capac-itor voltage divider formed by 119862

1 1198622 and 119862

3 as shown

in Figure 14 The simplified multilevel inverter topology is

Table 3 Switching pattern for the single-phase seven-level inverter

1198810

1198781

1198782

1198783

1198784

1198785

1198786

119881dc 1 0 0 1 0 02119881dc3 0 0 0 1 1 0119881dc3 0 0 0 1 0 10 0 0 1 1 0 00lowast 1 1 0 0 0 0minus119881dc3 0 1 0 0 1 0minus2119881dc3 0 1 0 0 0 1minus119881dc 0 1 1 0 0 0

significantly advantageous over other topologies The advan-tages of simplified topology are requirement of less powerswitch power diodes and less capacitors for this inverterPhotovoltaic arrays were connected to the inverter via a DC-DC SEPIC converter The power generated by the inverter isto be delivered to the power network so the utility grid ratherthan a load was used The DC-DC SEPIC converter wasrequired because the PV arrays had a voltage that was lowerthan the grid voltage High DC bus voltages are necessary toensure that power flows from the PV arrays to the grid Afiltering inductance 119871

119891was used to filter the current injected

into the grid Proper switching of the inverter can produceseven levels of output-voltage (119881dc 2119881dc3 119881dc3 0 0

lowastminus119881dc3 minus2119881dc3 minus119881dc) from the DC supply voltage Table 3shows the switching pattern for the single-phase simplifiedseven-level inverter

6 Grid-Connected Solar Power System

The modelling and simulation of PV MPPT CPWMSEPICconverter simplified seven-level MLI and controller had

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

2 International Journal of Photoenergy

Multilevel inverter consists of an array of power semi-conductor switches capacitor voltage sources and clampingdiodes The multilevel inverter produces the stepped voltagewaveforms with less distortion less switching frequencyhigher efficiency lower voltage devices and better electro-magnetic compatibility [15] The commutation (process ofturn off) of the switches permits the addition of the capacitorvoltages which reach high voltages at the output [16]

A modular grid-connected PV generation system pre-sents an actual behavioural model of a grid tied PV systemsuitable for system level investigations Simplified means formodelling the PV array and investigating a gradient basedMPPT into a very simple averaged model of the power con-verter was developed and themodel has been experimentallyvetted [17 18] A single-phase grid-connected inverter whichis usually used for residential or low-power applications ofpower ranges that are less than 10 kW [15] Types of single-phase grid-connected inverters have been investigated [19]A common topology of this inverter is full-bridge three-levelThe three-level inverter can satisfy specifications through itsvery high switching but it could also unfortunately increaseswitching losses acoustic noise and level of interference toother equipment Improving its output waveform reduces itsharmonic content and hence also the size of the filter usedand the level of electromagnetic interference (EMI) generatedby the inverterrsquos switching operation [20]

MATLAB-based modelling and simulation schemewhich is suitable for studying the 119868-119881 and 119875-119881 characteristicsof a PV array under a nonuniform insolation due to partialshading [21] was proposed The mathematical model of solarPV module is useful for the computer simulation The powerelectronics interface connected between a solar panel anda load or battery bus is a pulse width modulated (PWM)DC-DC converter or their derived circuits used to extractmaximum power from solar PV panel [22] The main draw-back of PV systems is that the output voltage of PV panels ishighly dependent on solar irradiance and ambient temper-ature Therefore PV panels outputs cannot connect directlyto the load To improve this a DC-DC boost converter isrequired to interface between PV panels and loads [23] Theboost converter is fixing the output voltage of the PV systemConverter receives the variable input voltage which is theoutput of PV panels and gives up constant output voltageacross its output capacitors where the loads can be connectedIn general a DC-DC boost converter operates at a certainduty cycle In this case the output voltage depends on thatduty cycle If the input voltage is changed while the duty cycleis kept constant the output voltage will vary Duty cycle isvaried by using a pulse width modulation (PWM) technique[24]

Silicon carbide (SiC) represents an advance in silicontechnology because it allows a larger energy gap SiC is classi-fied as a wide-band-gap (WBG) material and it is the main-stream material for power semiconductors [25 26] Amongthe different types of power semiconductors the power diodewas the best device to adopt SiC technologyThemain advan-tage of SiC is high-breakdown voltage and reverse-recoverycurrent is small [27ndash29] As a result higher efficiency andhigher power density can be brought to power electronic

Rp

RsID

DIsc

IPV

VPV

Figure 1 Equivalent circuit of solar PV module

systems in different applications [30 31] In this researcha new active snubber circuit is proposed to contrive a newfamily of PWM converters This proposed circuit providesperfectly ZVT turn on andZCT turn off together for themainswitch of a converter by using only one quasiresonant circuitwithout an important increase in the cost and complexityof the converter This paper proposes to implement ChaoticPWM as a control method to improve the steady state perfor-mance of the DC-DC SEPIC converter based MPPT systemfor solar PV module The nominal duty cycle of the mainswitch of DC-DC SEPIC converter is adjusted so that thesolar panel output impedance is equal to the input resistanceof the DC-DC converter which results in better spectralperformance in the tracked voltages when compared toconventional PWM control The conversion efficiency of theproposed MPPT system is increased when CPWM is usedthiswill be comparedwith parallel boost converterMultilevelinverters are promising as they have nearly sinusoidal output-voltage waveforms output current with better harmonicprofile less stressing of electronic components owing todecreased voltages switching losses that are lower than thoseof conventional two-level inverters a smaller filter size andlower EMI all of whichmake them cheaper lighter andmorecompact [29]

2 MATLAB Model of L1235-37WSolar PV Module

The output characteristics of the solar PVmodule depend onthe irradiance and the operating temperature of the cell Theequivalent circuit of PV module is shown in Figure 1

From Figure 1 the current and voltage equation is givenby

119868sc = 119868119863

+ 119868PV + (119881119863

119877119901

)

119881PV = 119881119863

minus (119868PV lowast 119877119904)

(1)

where diode current is 119868119863

= 119868119900

+ (119890(119881119863119881119879) minus 1)

Based on the electrical equation (1) and the solar PVmod-ule are modelled in MATLAB as shown in Figure 2 whichis used to enhance the understanding and predict the 119881-119868characteristics and to analyze the effect of temperature andirradiation variation If irradiance increases the fluctuationof the open-circuit voltage is very small But the short circuit

International Journal of Photoenergy 3

1000

Insolation

InsolationProduct

Voltage-current characteristics

Power-current characteristics

PV1

PV module (I)

IPV

IPV VPV

VPV

IPV ramp

PPV

PPV

PPV

Figure 2 MATLAB model for PV module

Figure 3 L1235-37W solar module under test

current has sharp fluctuations with respect to irradianceHowever for a rising operating temperature the open-circuitvoltage is decreased in a nonlinear fashion [4]

The 119881-119868 characteristics are validated experimentally inthe L1235-37Wp solar module as shown in Figure 3 Thetechnical specifications of L1235-37Wp solar module undertest are given inTable 1 Figure 4 shows the119881-119868 characteristicsof L1235-37Wp which is based on the experimental resultsunder irradiation (119866) = 1000Wm2 and temperature = 25∘C

21 Space Modelling of SEPIC Converter Input at MPP Therelation between input and output currents and voltage aregiven by

119881OUT119881IN

=119863

(1 minus 119863)

119868IN119868OUT

=119863

(1 minus 119863)

(2)

The duty cycle of the SEPIC converter under continuousconduction mode is given by

119863 =119881OUT + 119881

119863

119881IN + 119881OUT + 119881119863

(3)

Table 1 Specifications of L1235-37W solar PV panel

Short circuit current (119868sc) 25 AVoltage at MPP (119881

119898) 164

Current at MPP (119868119898) 225

Open circuit voltage (119881oc) 21 VLength 645mmWidth 530mmDepth 34mmWeight 4 kgMaximum power (119875max) 37W

3

25

2

15

1

05

00 5 10 15 20 25

Am

ps (A

)

Voltage (V)

MPP

Figure 4 119881-119868 characteristics of L 1235-37W solar panel

119881119863is the forward voltage drop across the diode (119863) The

maximum duty cycle is

119863max =119881OUT + 119881

119863

119881IN(MIN) + 119881OUT + 119881119863

(4)

The value of the inductor is selected based on the belowequations

1198711

= 1198712

= 119871 =119881IN(MIN) lowast 119863max

Δ119868119871

lowast 119891119878

(5)

4 International Journal of Photoenergy

Δ119868119871is the peak-to-peak ripple current at the minimum input

voltage and 119891119878is the switching frequency The value of 119862

1

depends on RMS current which is given by

1198681198621(RMS) = 119868OUT lowast radic

119881OUT + 119881119863

119881IN(MIN) (6)

The voltage rating of capacitor 1198621must be greater than the

input voltage The ripple voltage on 1198621is given by

Δ1198811198621

=119868(OUT) lowast 119863max

1198621

lowast 119891119878

(7)

The parameters governing the selection of the MOSFET arethe minimum threshold voltage 119881th(min) the on-resistance119877DS(ON) gate-drain charge 119876GD and the maximum drain tosource voltage 119881DS(max) The peak switch voltage is equal to119881IN + 119881OUT The peak switch current is given by

1198681198761(Peak) = 119868

1198711(PEAK) + 1198681198712(PEAK) (8)

The RMS current is given by

1198681198761(RMS) = 119868OUTradic(119881OUT + 119881IN(MIN)) lowast

119881OUT119881IN(MIN)2

(9)

The total power dissipation for MOSFETs includes conduc-tion loss (as shown in the first termof the above equation) andswitching loss (as shown in the second term) 119868

119866is the gate

drive current The 119877DS(ON) value should be selected at max-imum operating junction temperature and is typically givenin the MOSFET datasheet

119875switch = (1198681198761(RMS) lowast 119877DS(ON) lowast 119863MAX)

+ (119881IN(MIN) + 119881OUT) lowast 1198681198761(Peak) lowast

(119876GD lowast 119891119878)

119868119866

(10)

The output diode must be selected to handle the peak currentand the reverse voltage In a SEPIC converter the diode peakcurrent is the same as the switch peak current 119868

1198761(Peak) Theminimum peak reverse voltage the diode must withstand is

119881RD = 119881IN(MAX) + 119881OUT(MAX) (11)

22 Dynamic Input Characteristics of a SEPIC Converter atMPP The input voltage and the equivalent input resistanceof the converter are 119881

119878and 119877

119894 respectively As the input

power 120588119894to the converter is equal to the output power 120588

119900of

the solar PV module

120588119894= 120588119900

=1198812

119878

119877119894

(12)

The rate of change 120588119894with respect to 119881

119878and 119877

119894can be

shown below

120597120588119894=

2119881119878

119877119894

120597119881119878

minus1198812

119878

1198772

119894

120597119877119894 (13)

At the MPP the rate of change of 120588119894equals zero and 119877

119894=

119903119892

120597120588119894= 0 hence

120597119881119878

120597119877119894

=119881119878

2119877119894

(14)

The equation gives the required dynamic resistance char-acteristics of the tracker at MPP

23 Generation of Chaotic PWM In order to improve thesteady state performance of solar powered system direct con-trol Chaotic Pulse width modulated (CPWM) SEPIC con-verter is proposed to track maximum power from solar PVmodule Therefore in order to get chaotic frequency 119891

Δor

chaotic amplitude 119860Δ chaos-based PWM (CPWM) is ana-

lyzed to generate chaotic PWM The MATLAB simulation iscarried out as shown in Figure 5The analogue chaotic PWMhas its advantages over the digital in its low costs and easy-to-design making it suitable for high-frequency operation andsituations when design flexibility high converter conversionefficiency and low cost In order to generate chaotic pulsewidth modulation Chuarsquos diode is used to trigger the mainswitch of SEPIC converter and to be used for reducingspectral peaks in tracked converter voltage

The CPWM adopts sawtooth to modulate but its carrierperiod 119879

1015840

Δchanges according to

1198791015840

Δ=

119883119894

Mean (119909)lowast 119879Δ (15)

where 119879Δis invariant period 119883

119894 119894 = 1 2 119873 a chaotic

sequence 119909 = (1199091 1199092

119909119873

) and Mean(119909) average of thesequence defined as

Mean (119909) = Lim119873

sum

119894=1

10038161003816100381610038161198831198941003816100381610038161003816

1

119873 119873 997888rarr infin (16)

Similarly the CPWM also adopts sawtooth to modulate butits carrier amplitude 119860

1015840

Δchanges according to

1198601015840

Δ= 1 + 119870

119883119894

Mean (119909) 119860Δ (17)

where 119860Δis the invariant amplitude 119883

119894 119894 = 1 2 119873 a

chaotic sequence 119909 = (1199091 1199092

119909119873

) andMean(119909) average ofthe sequence and119870 is themodulation factor of the amplitudewhich can be set required in practice The value of 119870 isselected as low so that the ripple in the output voltage of theSEPIC converter is low Also the ripple in the output voltagecontrolled by chaotic PWM is lowThe analog chaotic carrieris generated based on the circuit the resistances (119877

1198891sdot sdot sdot 1198771198896

)

are used to realise linear resistor called Chua diodeThe para-meters for Chuarsquos diode are designed and chosen as 119877

1198891=

24 kΩ 1198771198892

= 33 kΩ 1198771198893

= 1198771198894

= 220 Ω and 1198771198895

= 1198771198896

=

20 kΩ The other parameters of Chuarsquos oscillator used in theexperiment are 119871

1= 22mH 119862

1= 47 nF 119862

2= 500 pF and

119877 = 175KΩ

International Journal of Photoenergy 5

Reset

Relational

Randomnumber

Discrete-time

Chaotic PWM

Chaos carrier

integrator1

A1

1z

operator1

Unit delay1

03ge

ge

Constant2

K Ts

z minus 1

Figure 5 Chaotic PWM pulse generation

Figure 6 Hardware setup

Figure 7 Chaotic PWM

24 Experimental Setup Standalone PV System Figure 6shows the experimental setup of the proposed SEPICconverter-based MPPT for solar PV module which is con-stituted by a power stage and a control circuit The powerstage includes an inductor 119871

1 1198712 capacitor 119862

1 1198622 a switch

119878 a load resistance and a solar PV module (L1235-37Wp)The analog chaotic carrier is generated based on the hardwareoutput of CPWM is in Figure 7

3 Mathematical Model for Parallel BoostConverter with Active Snubber Circuit

Figure 12 represents the circuit diagram of the parallel boostconverter with active snubber It consists of five inductors119871119891119894 1198711198912 1198711198771 1198711198772 119871119899and three capacitors 119862

119904 119862119903 119862119900 119881119892

and 119881119900represents supply and output voltage respectively

119878 (1198781 1198782) is an active primary switch 119863 (119863

1198911 1198631198912

) is a free-wheeling diode 119863

119904(1198631 1198632 1198633) is a Snubber diode and 119877

119871

is the load resistance 119878 (1198781 1198782 1198783) operates at a switching fre-

quency 119891119878with duty ratio 119889

Choose the switching frequency of switches 1198781

= 1198782

=

100KHz and 1198783

= 200KHzWhen 119878

1= 1198782

= 0 and 1198783

= 1 as in Figure 8

119889119894119871119865

119889119905=

1

119871119865

[119881119892

= 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

minus 119894119871119878]

(18)

Also the switches 1198781

= 1198782

= 1198783

= 1 as in Figure 9

119889119894119871119865

119889119905=

1

119871119865

[119881119892

minus 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

]

(19)

Similarly the switches 1198781

= 1198782

= 1 and 1198783

= 1 or 0 as inFigure 10

119889119894119871119865

119889119905=

119881119892

119871119865

119889119881119900

119889119905=

1

119862119900

[minus119881119900

119877119871

]

(20)

6 International Journal of Photoenergy

Vg

minus

+

Lf1

Lf2

Co RLLs Vo

iLs

iLf

Figure 8 When 1198781

= 1198782

= 0 and 1198783

= 1

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 9 When 1198781

= 1198782

= 1198783

= 1

By using state-space averagingmethod the state equationsduring switch-on and switch-off conditions are

1

=minus (1 minus 119889

1)

119871119865

1199092

minus(1 minus 119889

2)

119871119865

1199092

+

119881119892

119871119865

2

=minus1

119877119871119862119900

1199092

+(1 minus 119889

1) 1198892

119862119900

1199091

+(1 minus 119889

1) (1 minus 119889

2)

119862119900

1199091

(21)

where 1199091and 119909

2are the moving averages of 119894

119871119865and 119881

119900

respectively

4 Proposed Parallel Boost Converter forPV Application

Figure 11 shows the BlockDiagram of PV based parallel boostconverter with active snubber It is the combination of newactive snubber circuit with parallel boost converter Threeswitches 119878

1 1198782 and 119878

3are used 119878

1and 1198782act as main switch

and 1198783acts as an auxiliary switch 119878

1and 1198782are controlled by

ZVT and ZCT respectively also 1198783is controlled by ZCSThis

circuit operates with the input of solar powerAssume both the main switches (119878

1and 119878

2) operate in

the same frequency The features of proposed parallel boostconverter are as follows

(i) All the semiconductors work with soft switching inthe proposed converter

(ii) The main switches 1198781and 119878

2turn on with ZVT and

turn off with ZCT(iii) The secondary switch is turned on with ZCS and

turned off with ZCS

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 10 When 1198781

= 1198782

= 1 and 1198783

= 1 or 0

(iv) All other components of the parallel boost converterfunctions based on this soft switching

(v) There is no additional current or voltage force on themain switches 119878

1and 1198782

(vi) There is no additional current or voltage force on thesecondary switch 119878

3

(vii) Also there is no additional current or voltage force onthe main diodes 119863

1198911and 119863

1198912

(viii) According to the ratio of the transformer a part of theresonant current is transferred to the output loadwiththe coupling inductance So there is less current stresson the secondary switch with satisfied points

(ix) At resistive load condition in the ZVT process themain switches voltage falls to zero earlier due todecreased interval time and that does not make aproblem in the ZVT process for the main switch

(x) At resistive load condition in the ZCT process themain switches body diode on state time is increasedwhen the input current is decreased However thereis no effect on the main switch turn off process withZCT

(xi) This parallel boost converter operates in high-switch-ing frequency

(xii) This converter easily controls because the main andthe auxiliary switches are connected with commonground

(xiii) Themost attractive feature of this proposed converteris using ZVT and ZCT technique

(xiv) The proposed new active snubber circuit is easilyadopted with other basic PWM converters and alsoswitching converters

(xv) Additional passive snubber circuits are not necessaryfor this proposed converter

(xvi) SIC (silicon carbide) is used in the main and auxiliarydiodes so reverse recovery problem does not arise

(xvii) Theproposed active snubber circuit is also suitable forother DC-DC converters

41 Procedure for Constructing a Proposed Converter Steps toobtain a system level modeling and simulation of proposedpower electronic converter are listed below

International Journal of Photoenergy 7

Active snubber

Main diodesMain inductors MLI

Grid

Main capacitorMPPTSolar PV

Main switches

Snubber circuit

Auxiliary

Input source

(Lf1 Lf2)

Parallel boost converter

(S1 S2)

(L1235)

switch (S3)

Figure 11 Block diagram of PV based parallel boost converter with active snubber

Table 2 Specification of parallel boost converter with activeSnubber

Main inductor 1198711198911

750 120583HMain inductor 119871

1198912750 120583H

Upper Snubber inductor 1198711198771

5 120583HLower Snubber inductor 119871

1198772(119871119898

+ 119871119889) 2 120583H

Magnetization inductor 119871119872(119871119899

+ 1198710119897) 3 120583H

Parasitic capacitor 119862119904

1 120583FSnubber capacitor 119862

11987747 nF

Output capacitor 119862119900

330 120583F450VOutput load resistance 119877 = 119877

119871530Ω

(i) Determine the state variables of the proposed powercircuit in order to write its switched state-spacemodel for example inductance current and capaci-tance voltage

(ii) Assign integer variables (ON-1 and OFF-0 state) tothe proposed power semiconductor to each switchingcircuit

(iii) Determine the conditions controlling the states ofthe proposed power semiconductors or the switchingcircuit

(iv) Assume the main operating modes apply Kirchhoff rsquosCurrent law and Kirchhoff rsquos Voltage law and combineall the required stages into a switched state-spacemodel which is the desired system-level of the pro-posed model

(v) Implement the derived equations with MATLABSimulink

(vi) Use the obtained switched space-state model todesign linear or nonlinear controllers for the pro-posed power converter

The algorithm for solving the differential equations andthe step size should be chosen before running any simulationThis step is only suitable in closed-loop simulations [21]

42 Operation of Proposed Boost Converter with Snubber Cir-cuit Theproposed PV based converter is shown in Figure 12and it is based on a dual boost circuit where the first one(switch 119878

1and choke 119871

1198911) is used asmain chock of boost con-

verter circuit and where the second one (switch 1198782and choke

1198711198912) is used to perform an active filtering The proposed

converter applies active snubber circuit for soft switchingThis snubber circuit is built on the ZVT turn on andZCT turnoff processes of the main switches Specification of proposedparallel boost converter with active snubber is in Table 2

The power from the solar flows through the two parallelpaths High efficiency was obtained by this method So asto reach soft switching (SS) for the main and the auxiliaryswitches main switches turn on with ZVT and turn off withZCT The proposed converter utilizes active snubber circuitfor SS This snubber circuit is mostly based on the ZVT turnon and ZCT turn off processes of the main switch 119871

1198772value

is limited with (119881out1198711198772

)119905rise1198782 le 119868119894max to conduct maximum

input current at the end of the auxiliary switch rise time(119905rise1198782) and119871

1198771ge 21198711198772 To turn off 119878

1with ZCT the duration

of 119905ZCT is at least longer than fall time of 1198781(119905fall1198781)119905ZCT ge

119905fall1198781 Though the main switches are in off state the controlsignal is functional to the auxiliary switch The parasiticcapacitor of the main switch should be discharged absolutelyand themain switches antiparallel diode should be turned onThe on state time of the antiparallel diode is named 119905ZVT andin this time period the gate signal of the main switch wouldbe applied So the main switch is turned on below ZVS andZCS with ZVT

Whereas the main switches are in on state and ways inputcurrent the control signal of the auxiliary switch is appliedAfter the resonant starts the resonant current should behigher than the input current to turn on the antiparallel diodeof the main switchThe on state time of the antiparallel diode(119905ZCT) has to be longer than the main switches fall time (119905

1198911198781)

After all these terms are completed while antiparallel diodeis in on state the gate signal of the main switch should becutoff to provide ZCT for the main switch Auxiliary switchturn on with ZCS and turn off with ZCSThe auxiliary switchis turned on with ZCS for the coupling inductance limits thecurrent rise speed

8 International Journal of Photoenergy

Lf1

Lf2

S1 S2

S3

D2

Ld

Lm

LR1

D1

Ln

RLoad

Co

Lo1 D4

Df1

Df2

D3

CR

PVArray

Figure 12 Circuit diagram of PV based parallel boost converter with active snubber with resistive load

The current passing through the coupling inductancemust be partial to conductmaximum input current at the endof the auxiliary switch rise time (119905

1199031198783) So the turn on process

of the auxiliary switch with ZCS is offered To turn off theauxiliary switch with ZCS though the auxiliary switch is inon state the current passing through the switch should fallto zero with a new resonant Then the control signal can becutoff If 119862

119878is ignored 119871

1198771value should be two times added

with 1198711198772

to make the auxiliary switch current fall to zero Asthe current cannot stay at zero as long as the auxiliary switchfall time (119905

1198911198783) the auxiliary switch is turned off nearly with

ZCSThe proposed Simulink topology is shown in Figure 13

The inductors 1198711198911

and 1198711198912

have the similar values the diodes1198631198911-1198631198912

are at the same type and the same guess was for theswitches (119878

1amp 1198782) All the inductors have individual switches

and they resemble paralleling of classic converters

5 Design of MLI Module

A multilevel converter is a power electronic system thatsynthesizes a desired output voltage levels from theDC inputssupply Compared with the traditional two-level voltageconverter the primary advantage of multilevel converters istheir smaller output voltage step which results in high powerquality lower harmonic components better electromagneticcompatibility and lower switching losses The functionalityverification of the simplified seven-level inverter is doneusing MATLAB simulation which is shown in Figure 14

This single-phase simplified seven-level inverter wasdeveloped using a single-phase full bridge (H-bridge)inverter two bidirectional auxiliary switches and a capac-itor voltage divider formed by 119862

1 1198622 and 119862

3 as shown

in Figure 14 The simplified multilevel inverter topology is

Table 3 Switching pattern for the single-phase seven-level inverter

1198810

1198781

1198782

1198783

1198784

1198785

1198786

119881dc 1 0 0 1 0 02119881dc3 0 0 0 1 1 0119881dc3 0 0 0 1 0 10 0 0 1 1 0 00lowast 1 1 0 0 0 0minus119881dc3 0 1 0 0 1 0minus2119881dc3 0 1 0 0 0 1minus119881dc 0 1 1 0 0 0

significantly advantageous over other topologies The advan-tages of simplified topology are requirement of less powerswitch power diodes and less capacitors for this inverterPhotovoltaic arrays were connected to the inverter via a DC-DC SEPIC converter The power generated by the inverter isto be delivered to the power network so the utility grid ratherthan a load was used The DC-DC SEPIC converter wasrequired because the PV arrays had a voltage that was lowerthan the grid voltage High DC bus voltages are necessary toensure that power flows from the PV arrays to the grid Afiltering inductance 119871

119891was used to filter the current injected

into the grid Proper switching of the inverter can produceseven levels of output-voltage (119881dc 2119881dc3 119881dc3 0 0

lowastminus119881dc3 minus2119881dc3 minus119881dc) from the DC supply voltage Table 3shows the switching pattern for the single-phase simplifiedseven-level inverter

6 Grid-Connected Solar Power System

The modelling and simulation of PV MPPT CPWMSEPICconverter simplified seven-level MLI and controller had

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

International Journal of Photoenergy 3

1000

Insolation

InsolationProduct

Voltage-current characteristics

Power-current characteristics

PV1

PV module (I)

IPV

IPV VPV

VPV

IPV ramp

PPV

PPV

PPV

Figure 2 MATLAB model for PV module

Figure 3 L1235-37W solar module under test

current has sharp fluctuations with respect to irradianceHowever for a rising operating temperature the open-circuitvoltage is decreased in a nonlinear fashion [4]

The 119881-119868 characteristics are validated experimentally inthe L1235-37Wp solar module as shown in Figure 3 Thetechnical specifications of L1235-37Wp solar module undertest are given inTable 1 Figure 4 shows the119881-119868 characteristicsof L1235-37Wp which is based on the experimental resultsunder irradiation (119866) = 1000Wm2 and temperature = 25∘C

21 Space Modelling of SEPIC Converter Input at MPP Therelation between input and output currents and voltage aregiven by

119881OUT119881IN

=119863

(1 minus 119863)

119868IN119868OUT

=119863

(1 minus 119863)

(2)

The duty cycle of the SEPIC converter under continuousconduction mode is given by

119863 =119881OUT + 119881

119863

119881IN + 119881OUT + 119881119863

(3)

Table 1 Specifications of L1235-37W solar PV panel

Short circuit current (119868sc) 25 AVoltage at MPP (119881

119898) 164

Current at MPP (119868119898) 225

Open circuit voltage (119881oc) 21 VLength 645mmWidth 530mmDepth 34mmWeight 4 kgMaximum power (119875max) 37W

3

25

2

15

1

05

00 5 10 15 20 25

Am

ps (A

)

Voltage (V)

MPP

Figure 4 119881-119868 characteristics of L 1235-37W solar panel

119881119863is the forward voltage drop across the diode (119863) The

maximum duty cycle is

119863max =119881OUT + 119881

119863

119881IN(MIN) + 119881OUT + 119881119863

(4)

The value of the inductor is selected based on the belowequations

1198711

= 1198712

= 119871 =119881IN(MIN) lowast 119863max

Δ119868119871

lowast 119891119878

(5)

4 International Journal of Photoenergy

Δ119868119871is the peak-to-peak ripple current at the minimum input

voltage and 119891119878is the switching frequency The value of 119862

1

depends on RMS current which is given by

1198681198621(RMS) = 119868OUT lowast radic

119881OUT + 119881119863

119881IN(MIN) (6)

The voltage rating of capacitor 1198621must be greater than the

input voltage The ripple voltage on 1198621is given by

Δ1198811198621

=119868(OUT) lowast 119863max

1198621

lowast 119891119878

(7)

The parameters governing the selection of the MOSFET arethe minimum threshold voltage 119881th(min) the on-resistance119877DS(ON) gate-drain charge 119876GD and the maximum drain tosource voltage 119881DS(max) The peak switch voltage is equal to119881IN + 119881OUT The peak switch current is given by

1198681198761(Peak) = 119868

1198711(PEAK) + 1198681198712(PEAK) (8)

The RMS current is given by

1198681198761(RMS) = 119868OUTradic(119881OUT + 119881IN(MIN)) lowast

119881OUT119881IN(MIN)2

(9)

The total power dissipation for MOSFETs includes conduc-tion loss (as shown in the first termof the above equation) andswitching loss (as shown in the second term) 119868

119866is the gate

drive current The 119877DS(ON) value should be selected at max-imum operating junction temperature and is typically givenin the MOSFET datasheet

119875switch = (1198681198761(RMS) lowast 119877DS(ON) lowast 119863MAX)

+ (119881IN(MIN) + 119881OUT) lowast 1198681198761(Peak) lowast

(119876GD lowast 119891119878)

119868119866

(10)

The output diode must be selected to handle the peak currentand the reverse voltage In a SEPIC converter the diode peakcurrent is the same as the switch peak current 119868

1198761(Peak) Theminimum peak reverse voltage the diode must withstand is

119881RD = 119881IN(MAX) + 119881OUT(MAX) (11)

22 Dynamic Input Characteristics of a SEPIC Converter atMPP The input voltage and the equivalent input resistanceof the converter are 119881

119878and 119877

119894 respectively As the input

power 120588119894to the converter is equal to the output power 120588

119900of

the solar PV module

120588119894= 120588119900

=1198812

119878

119877119894

(12)

The rate of change 120588119894with respect to 119881

119878and 119877

119894can be

shown below

120597120588119894=

2119881119878

119877119894

120597119881119878

minus1198812

119878

1198772

119894

120597119877119894 (13)

At the MPP the rate of change of 120588119894equals zero and 119877

119894=

119903119892

120597120588119894= 0 hence

120597119881119878

120597119877119894

=119881119878

2119877119894

(14)

The equation gives the required dynamic resistance char-acteristics of the tracker at MPP

23 Generation of Chaotic PWM In order to improve thesteady state performance of solar powered system direct con-trol Chaotic Pulse width modulated (CPWM) SEPIC con-verter is proposed to track maximum power from solar PVmodule Therefore in order to get chaotic frequency 119891

Δor

chaotic amplitude 119860Δ chaos-based PWM (CPWM) is ana-

lyzed to generate chaotic PWM The MATLAB simulation iscarried out as shown in Figure 5The analogue chaotic PWMhas its advantages over the digital in its low costs and easy-to-design making it suitable for high-frequency operation andsituations when design flexibility high converter conversionefficiency and low cost In order to generate chaotic pulsewidth modulation Chuarsquos diode is used to trigger the mainswitch of SEPIC converter and to be used for reducingspectral peaks in tracked converter voltage

The CPWM adopts sawtooth to modulate but its carrierperiod 119879

1015840

Δchanges according to

1198791015840

Δ=

119883119894

Mean (119909)lowast 119879Δ (15)

where 119879Δis invariant period 119883

119894 119894 = 1 2 119873 a chaotic

sequence 119909 = (1199091 1199092

119909119873

) and Mean(119909) average of thesequence defined as

Mean (119909) = Lim119873

sum

119894=1

10038161003816100381610038161198831198941003816100381610038161003816

1

119873 119873 997888rarr infin (16)

Similarly the CPWM also adopts sawtooth to modulate butits carrier amplitude 119860

1015840

Δchanges according to

1198601015840

Δ= 1 + 119870

119883119894

Mean (119909) 119860Δ (17)

where 119860Δis the invariant amplitude 119883

119894 119894 = 1 2 119873 a

chaotic sequence 119909 = (1199091 1199092

119909119873

) andMean(119909) average ofthe sequence and119870 is themodulation factor of the amplitudewhich can be set required in practice The value of 119870 isselected as low so that the ripple in the output voltage of theSEPIC converter is low Also the ripple in the output voltagecontrolled by chaotic PWM is lowThe analog chaotic carrieris generated based on the circuit the resistances (119877

1198891sdot sdot sdot 1198771198896

)

are used to realise linear resistor called Chua diodeThe para-meters for Chuarsquos diode are designed and chosen as 119877

1198891=

24 kΩ 1198771198892

= 33 kΩ 1198771198893

= 1198771198894

= 220 Ω and 1198771198895

= 1198771198896

=

20 kΩ The other parameters of Chuarsquos oscillator used in theexperiment are 119871

1= 22mH 119862

1= 47 nF 119862

2= 500 pF and

119877 = 175KΩ

International Journal of Photoenergy 5

Reset

Relational

Randomnumber

Discrete-time

Chaotic PWM

Chaos carrier

integrator1

A1

1z

operator1

Unit delay1

03ge

ge

Constant2

K Ts

z minus 1

Figure 5 Chaotic PWM pulse generation

Figure 6 Hardware setup

Figure 7 Chaotic PWM

24 Experimental Setup Standalone PV System Figure 6shows the experimental setup of the proposed SEPICconverter-based MPPT for solar PV module which is con-stituted by a power stage and a control circuit The powerstage includes an inductor 119871

1 1198712 capacitor 119862

1 1198622 a switch

119878 a load resistance and a solar PV module (L1235-37Wp)The analog chaotic carrier is generated based on the hardwareoutput of CPWM is in Figure 7

3 Mathematical Model for Parallel BoostConverter with Active Snubber Circuit

Figure 12 represents the circuit diagram of the parallel boostconverter with active snubber It consists of five inductors119871119891119894 1198711198912 1198711198771 1198711198772 119871119899and three capacitors 119862

119904 119862119903 119862119900 119881119892

and 119881119900represents supply and output voltage respectively

119878 (1198781 1198782) is an active primary switch 119863 (119863

1198911 1198631198912

) is a free-wheeling diode 119863

119904(1198631 1198632 1198633) is a Snubber diode and 119877

119871

is the load resistance 119878 (1198781 1198782 1198783) operates at a switching fre-

quency 119891119878with duty ratio 119889

Choose the switching frequency of switches 1198781

= 1198782

=

100KHz and 1198783

= 200KHzWhen 119878

1= 1198782

= 0 and 1198783

= 1 as in Figure 8

119889119894119871119865

119889119905=

1

119871119865

[119881119892

= 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

minus 119894119871119878]

(18)

Also the switches 1198781

= 1198782

= 1198783

= 1 as in Figure 9

119889119894119871119865

119889119905=

1

119871119865

[119881119892

minus 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

]

(19)

Similarly the switches 1198781

= 1198782

= 1 and 1198783

= 1 or 0 as inFigure 10

119889119894119871119865

119889119905=

119881119892

119871119865

119889119881119900

119889119905=

1

119862119900

[minus119881119900

119877119871

]

(20)

6 International Journal of Photoenergy

Vg

minus

+

Lf1

Lf2

Co RLLs Vo

iLs

iLf

Figure 8 When 1198781

= 1198782

= 0 and 1198783

= 1

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 9 When 1198781

= 1198782

= 1198783

= 1

By using state-space averagingmethod the state equationsduring switch-on and switch-off conditions are

1

=minus (1 minus 119889

1)

119871119865

1199092

minus(1 minus 119889

2)

119871119865

1199092

+

119881119892

119871119865

2

=minus1

119877119871119862119900

1199092

+(1 minus 119889

1) 1198892

119862119900

1199091

+(1 minus 119889

1) (1 minus 119889

2)

119862119900

1199091

(21)

where 1199091and 119909

2are the moving averages of 119894

119871119865and 119881

119900

respectively

4 Proposed Parallel Boost Converter forPV Application

Figure 11 shows the BlockDiagram of PV based parallel boostconverter with active snubber It is the combination of newactive snubber circuit with parallel boost converter Threeswitches 119878

1 1198782 and 119878

3are used 119878

1and 1198782act as main switch

and 1198783acts as an auxiliary switch 119878

1and 1198782are controlled by

ZVT and ZCT respectively also 1198783is controlled by ZCSThis

circuit operates with the input of solar powerAssume both the main switches (119878

1and 119878

2) operate in

the same frequency The features of proposed parallel boostconverter are as follows

(i) All the semiconductors work with soft switching inthe proposed converter

(ii) The main switches 1198781and 119878

2turn on with ZVT and

turn off with ZCT(iii) The secondary switch is turned on with ZCS and

turned off with ZCS

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 10 When 1198781

= 1198782

= 1 and 1198783

= 1 or 0

(iv) All other components of the parallel boost converterfunctions based on this soft switching

(v) There is no additional current or voltage force on themain switches 119878

1and 1198782

(vi) There is no additional current or voltage force on thesecondary switch 119878

3

(vii) Also there is no additional current or voltage force onthe main diodes 119863

1198911and 119863

1198912

(viii) According to the ratio of the transformer a part of theresonant current is transferred to the output loadwiththe coupling inductance So there is less current stresson the secondary switch with satisfied points

(ix) At resistive load condition in the ZVT process themain switches voltage falls to zero earlier due todecreased interval time and that does not make aproblem in the ZVT process for the main switch

(x) At resistive load condition in the ZCT process themain switches body diode on state time is increasedwhen the input current is decreased However thereis no effect on the main switch turn off process withZCT

(xi) This parallel boost converter operates in high-switch-ing frequency

(xii) This converter easily controls because the main andthe auxiliary switches are connected with commonground

(xiii) Themost attractive feature of this proposed converteris using ZVT and ZCT technique

(xiv) The proposed new active snubber circuit is easilyadopted with other basic PWM converters and alsoswitching converters

(xv) Additional passive snubber circuits are not necessaryfor this proposed converter

(xvi) SIC (silicon carbide) is used in the main and auxiliarydiodes so reverse recovery problem does not arise

(xvii) Theproposed active snubber circuit is also suitable forother DC-DC converters

41 Procedure for Constructing a Proposed Converter Steps toobtain a system level modeling and simulation of proposedpower electronic converter are listed below

International Journal of Photoenergy 7

Active snubber

Main diodesMain inductors MLI

Grid

Main capacitorMPPTSolar PV

Main switches

Snubber circuit

Auxiliary

Input source

(Lf1 Lf2)

Parallel boost converter

(S1 S2)

(L1235)

switch (S3)

Figure 11 Block diagram of PV based parallel boost converter with active snubber

Table 2 Specification of parallel boost converter with activeSnubber

Main inductor 1198711198911

750 120583HMain inductor 119871

1198912750 120583H

Upper Snubber inductor 1198711198771

5 120583HLower Snubber inductor 119871

1198772(119871119898

+ 119871119889) 2 120583H

Magnetization inductor 119871119872(119871119899

+ 1198710119897) 3 120583H

Parasitic capacitor 119862119904

1 120583FSnubber capacitor 119862

11987747 nF

Output capacitor 119862119900

330 120583F450VOutput load resistance 119877 = 119877

119871530Ω

(i) Determine the state variables of the proposed powercircuit in order to write its switched state-spacemodel for example inductance current and capaci-tance voltage

(ii) Assign integer variables (ON-1 and OFF-0 state) tothe proposed power semiconductor to each switchingcircuit

(iii) Determine the conditions controlling the states ofthe proposed power semiconductors or the switchingcircuit

(iv) Assume the main operating modes apply Kirchhoff rsquosCurrent law and Kirchhoff rsquos Voltage law and combineall the required stages into a switched state-spacemodel which is the desired system-level of the pro-posed model

(v) Implement the derived equations with MATLABSimulink

(vi) Use the obtained switched space-state model todesign linear or nonlinear controllers for the pro-posed power converter

The algorithm for solving the differential equations andthe step size should be chosen before running any simulationThis step is only suitable in closed-loop simulations [21]

42 Operation of Proposed Boost Converter with Snubber Cir-cuit Theproposed PV based converter is shown in Figure 12and it is based on a dual boost circuit where the first one(switch 119878

1and choke 119871

1198911) is used asmain chock of boost con-

verter circuit and where the second one (switch 1198782and choke

1198711198912) is used to perform an active filtering The proposed

converter applies active snubber circuit for soft switchingThis snubber circuit is built on the ZVT turn on andZCT turnoff processes of the main switches Specification of proposedparallel boost converter with active snubber is in Table 2

The power from the solar flows through the two parallelpaths High efficiency was obtained by this method So asto reach soft switching (SS) for the main and the auxiliaryswitches main switches turn on with ZVT and turn off withZCT The proposed converter utilizes active snubber circuitfor SS This snubber circuit is mostly based on the ZVT turnon and ZCT turn off processes of the main switch 119871

1198772value

is limited with (119881out1198711198772

)119905rise1198782 le 119868119894max to conduct maximum

input current at the end of the auxiliary switch rise time(119905rise1198782) and119871

1198771ge 21198711198772 To turn off 119878

1with ZCT the duration

of 119905ZCT is at least longer than fall time of 1198781(119905fall1198781)119905ZCT ge

119905fall1198781 Though the main switches are in off state the controlsignal is functional to the auxiliary switch The parasiticcapacitor of the main switch should be discharged absolutelyand themain switches antiparallel diode should be turned onThe on state time of the antiparallel diode is named 119905ZVT andin this time period the gate signal of the main switch wouldbe applied So the main switch is turned on below ZVS andZCS with ZVT

Whereas the main switches are in on state and ways inputcurrent the control signal of the auxiliary switch is appliedAfter the resonant starts the resonant current should behigher than the input current to turn on the antiparallel diodeof the main switchThe on state time of the antiparallel diode(119905ZCT) has to be longer than the main switches fall time (119905

1198911198781)

After all these terms are completed while antiparallel diodeis in on state the gate signal of the main switch should becutoff to provide ZCT for the main switch Auxiliary switchturn on with ZCS and turn off with ZCSThe auxiliary switchis turned on with ZCS for the coupling inductance limits thecurrent rise speed

8 International Journal of Photoenergy

Lf1

Lf2

S1 S2

S3

D2

Ld

Lm

LR1

D1

Ln

RLoad

Co

Lo1 D4

Df1

Df2

D3

CR

PVArray

Figure 12 Circuit diagram of PV based parallel boost converter with active snubber with resistive load

The current passing through the coupling inductancemust be partial to conductmaximum input current at the endof the auxiliary switch rise time (119905

1199031198783) So the turn on process

of the auxiliary switch with ZCS is offered To turn off theauxiliary switch with ZCS though the auxiliary switch is inon state the current passing through the switch should fallto zero with a new resonant Then the control signal can becutoff If 119862

119878is ignored 119871

1198771value should be two times added

with 1198711198772

to make the auxiliary switch current fall to zero Asthe current cannot stay at zero as long as the auxiliary switchfall time (119905

1198911198783) the auxiliary switch is turned off nearly with

ZCSThe proposed Simulink topology is shown in Figure 13

The inductors 1198711198911

and 1198711198912

have the similar values the diodes1198631198911-1198631198912

are at the same type and the same guess was for theswitches (119878

1amp 1198782) All the inductors have individual switches

and they resemble paralleling of classic converters

5 Design of MLI Module

A multilevel converter is a power electronic system thatsynthesizes a desired output voltage levels from theDC inputssupply Compared with the traditional two-level voltageconverter the primary advantage of multilevel converters istheir smaller output voltage step which results in high powerquality lower harmonic components better electromagneticcompatibility and lower switching losses The functionalityverification of the simplified seven-level inverter is doneusing MATLAB simulation which is shown in Figure 14

This single-phase simplified seven-level inverter wasdeveloped using a single-phase full bridge (H-bridge)inverter two bidirectional auxiliary switches and a capac-itor voltage divider formed by 119862

1 1198622 and 119862

3 as shown

in Figure 14 The simplified multilevel inverter topology is

Table 3 Switching pattern for the single-phase seven-level inverter

1198810

1198781

1198782

1198783

1198784

1198785

1198786

119881dc 1 0 0 1 0 02119881dc3 0 0 0 1 1 0119881dc3 0 0 0 1 0 10 0 0 1 1 0 00lowast 1 1 0 0 0 0minus119881dc3 0 1 0 0 1 0minus2119881dc3 0 1 0 0 0 1minus119881dc 0 1 1 0 0 0

significantly advantageous over other topologies The advan-tages of simplified topology are requirement of less powerswitch power diodes and less capacitors for this inverterPhotovoltaic arrays were connected to the inverter via a DC-DC SEPIC converter The power generated by the inverter isto be delivered to the power network so the utility grid ratherthan a load was used The DC-DC SEPIC converter wasrequired because the PV arrays had a voltage that was lowerthan the grid voltage High DC bus voltages are necessary toensure that power flows from the PV arrays to the grid Afiltering inductance 119871

119891was used to filter the current injected

into the grid Proper switching of the inverter can produceseven levels of output-voltage (119881dc 2119881dc3 119881dc3 0 0

lowastminus119881dc3 minus2119881dc3 minus119881dc) from the DC supply voltage Table 3shows the switching pattern for the single-phase simplifiedseven-level inverter

6 Grid-Connected Solar Power System

The modelling and simulation of PV MPPT CPWMSEPICconverter simplified seven-level MLI and controller had

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

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Journal of

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Analytical ChemistryInternational Journal of

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Journal of

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Quantum Chemistry

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Organic Chemistry International

ElectrochemistryInternational Journal of

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Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

4 International Journal of Photoenergy

Δ119868119871is the peak-to-peak ripple current at the minimum input

voltage and 119891119878is the switching frequency The value of 119862

1

depends on RMS current which is given by

1198681198621(RMS) = 119868OUT lowast radic

119881OUT + 119881119863

119881IN(MIN) (6)

The voltage rating of capacitor 1198621must be greater than the

input voltage The ripple voltage on 1198621is given by

Δ1198811198621

=119868(OUT) lowast 119863max

1198621

lowast 119891119878

(7)

The parameters governing the selection of the MOSFET arethe minimum threshold voltage 119881th(min) the on-resistance119877DS(ON) gate-drain charge 119876GD and the maximum drain tosource voltage 119881DS(max) The peak switch voltage is equal to119881IN + 119881OUT The peak switch current is given by

1198681198761(Peak) = 119868

1198711(PEAK) + 1198681198712(PEAK) (8)

The RMS current is given by

1198681198761(RMS) = 119868OUTradic(119881OUT + 119881IN(MIN)) lowast

119881OUT119881IN(MIN)2

(9)

The total power dissipation for MOSFETs includes conduc-tion loss (as shown in the first termof the above equation) andswitching loss (as shown in the second term) 119868

119866is the gate

drive current The 119877DS(ON) value should be selected at max-imum operating junction temperature and is typically givenin the MOSFET datasheet

119875switch = (1198681198761(RMS) lowast 119877DS(ON) lowast 119863MAX)

+ (119881IN(MIN) + 119881OUT) lowast 1198681198761(Peak) lowast

(119876GD lowast 119891119878)

119868119866

(10)

The output diode must be selected to handle the peak currentand the reverse voltage In a SEPIC converter the diode peakcurrent is the same as the switch peak current 119868

1198761(Peak) Theminimum peak reverse voltage the diode must withstand is

119881RD = 119881IN(MAX) + 119881OUT(MAX) (11)

22 Dynamic Input Characteristics of a SEPIC Converter atMPP The input voltage and the equivalent input resistanceof the converter are 119881

119878and 119877

119894 respectively As the input

power 120588119894to the converter is equal to the output power 120588

119900of

the solar PV module

120588119894= 120588119900

=1198812

119878

119877119894

(12)

The rate of change 120588119894with respect to 119881

119878and 119877

119894can be

shown below

120597120588119894=

2119881119878

119877119894

120597119881119878

minus1198812

119878

1198772

119894

120597119877119894 (13)

At the MPP the rate of change of 120588119894equals zero and 119877

119894=

119903119892

120597120588119894= 0 hence

120597119881119878

120597119877119894

=119881119878

2119877119894

(14)

The equation gives the required dynamic resistance char-acteristics of the tracker at MPP

23 Generation of Chaotic PWM In order to improve thesteady state performance of solar powered system direct con-trol Chaotic Pulse width modulated (CPWM) SEPIC con-verter is proposed to track maximum power from solar PVmodule Therefore in order to get chaotic frequency 119891

Δor

chaotic amplitude 119860Δ chaos-based PWM (CPWM) is ana-

lyzed to generate chaotic PWM The MATLAB simulation iscarried out as shown in Figure 5The analogue chaotic PWMhas its advantages over the digital in its low costs and easy-to-design making it suitable for high-frequency operation andsituations when design flexibility high converter conversionefficiency and low cost In order to generate chaotic pulsewidth modulation Chuarsquos diode is used to trigger the mainswitch of SEPIC converter and to be used for reducingspectral peaks in tracked converter voltage

The CPWM adopts sawtooth to modulate but its carrierperiod 119879

1015840

Δchanges according to

1198791015840

Δ=

119883119894

Mean (119909)lowast 119879Δ (15)

where 119879Δis invariant period 119883

119894 119894 = 1 2 119873 a chaotic

sequence 119909 = (1199091 1199092

119909119873

) and Mean(119909) average of thesequence defined as

Mean (119909) = Lim119873

sum

119894=1

10038161003816100381610038161198831198941003816100381610038161003816

1

119873 119873 997888rarr infin (16)

Similarly the CPWM also adopts sawtooth to modulate butits carrier amplitude 119860

1015840

Δchanges according to

1198601015840

Δ= 1 + 119870

119883119894

Mean (119909) 119860Δ (17)

where 119860Δis the invariant amplitude 119883

119894 119894 = 1 2 119873 a

chaotic sequence 119909 = (1199091 1199092

119909119873

) andMean(119909) average ofthe sequence and119870 is themodulation factor of the amplitudewhich can be set required in practice The value of 119870 isselected as low so that the ripple in the output voltage of theSEPIC converter is low Also the ripple in the output voltagecontrolled by chaotic PWM is lowThe analog chaotic carrieris generated based on the circuit the resistances (119877

1198891sdot sdot sdot 1198771198896

)

are used to realise linear resistor called Chua diodeThe para-meters for Chuarsquos diode are designed and chosen as 119877

1198891=

24 kΩ 1198771198892

= 33 kΩ 1198771198893

= 1198771198894

= 220 Ω and 1198771198895

= 1198771198896

=

20 kΩ The other parameters of Chuarsquos oscillator used in theexperiment are 119871

1= 22mH 119862

1= 47 nF 119862

2= 500 pF and

119877 = 175KΩ

International Journal of Photoenergy 5

Reset

Relational

Randomnumber

Discrete-time

Chaotic PWM

Chaos carrier

integrator1

A1

1z

operator1

Unit delay1

03ge

ge

Constant2

K Ts

z minus 1

Figure 5 Chaotic PWM pulse generation

Figure 6 Hardware setup

Figure 7 Chaotic PWM

24 Experimental Setup Standalone PV System Figure 6shows the experimental setup of the proposed SEPICconverter-based MPPT for solar PV module which is con-stituted by a power stage and a control circuit The powerstage includes an inductor 119871

1 1198712 capacitor 119862

1 1198622 a switch

119878 a load resistance and a solar PV module (L1235-37Wp)The analog chaotic carrier is generated based on the hardwareoutput of CPWM is in Figure 7

3 Mathematical Model for Parallel BoostConverter with Active Snubber Circuit

Figure 12 represents the circuit diagram of the parallel boostconverter with active snubber It consists of five inductors119871119891119894 1198711198912 1198711198771 1198711198772 119871119899and three capacitors 119862

119904 119862119903 119862119900 119881119892

and 119881119900represents supply and output voltage respectively

119878 (1198781 1198782) is an active primary switch 119863 (119863

1198911 1198631198912

) is a free-wheeling diode 119863

119904(1198631 1198632 1198633) is a Snubber diode and 119877

119871

is the load resistance 119878 (1198781 1198782 1198783) operates at a switching fre-

quency 119891119878with duty ratio 119889

Choose the switching frequency of switches 1198781

= 1198782

=

100KHz and 1198783

= 200KHzWhen 119878

1= 1198782

= 0 and 1198783

= 1 as in Figure 8

119889119894119871119865

119889119905=

1

119871119865

[119881119892

= 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

minus 119894119871119878]

(18)

Also the switches 1198781

= 1198782

= 1198783

= 1 as in Figure 9

119889119894119871119865

119889119905=

1

119871119865

[119881119892

minus 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

]

(19)

Similarly the switches 1198781

= 1198782

= 1 and 1198783

= 1 or 0 as inFigure 10

119889119894119871119865

119889119905=

119881119892

119871119865

119889119881119900

119889119905=

1

119862119900

[minus119881119900

119877119871

]

(20)

6 International Journal of Photoenergy

Vg

minus

+

Lf1

Lf2

Co RLLs Vo

iLs

iLf

Figure 8 When 1198781

= 1198782

= 0 and 1198783

= 1

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 9 When 1198781

= 1198782

= 1198783

= 1

By using state-space averagingmethod the state equationsduring switch-on and switch-off conditions are

1

=minus (1 minus 119889

1)

119871119865

1199092

minus(1 minus 119889

2)

119871119865

1199092

+

119881119892

119871119865

2

=minus1

119877119871119862119900

1199092

+(1 minus 119889

1) 1198892

119862119900

1199091

+(1 minus 119889

1) (1 minus 119889

2)

119862119900

1199091

(21)

where 1199091and 119909

2are the moving averages of 119894

119871119865and 119881

119900

respectively

4 Proposed Parallel Boost Converter forPV Application

Figure 11 shows the BlockDiagram of PV based parallel boostconverter with active snubber It is the combination of newactive snubber circuit with parallel boost converter Threeswitches 119878

1 1198782 and 119878

3are used 119878

1and 1198782act as main switch

and 1198783acts as an auxiliary switch 119878

1and 1198782are controlled by

ZVT and ZCT respectively also 1198783is controlled by ZCSThis

circuit operates with the input of solar powerAssume both the main switches (119878

1and 119878

2) operate in

the same frequency The features of proposed parallel boostconverter are as follows

(i) All the semiconductors work with soft switching inthe proposed converter

(ii) The main switches 1198781and 119878

2turn on with ZVT and

turn off with ZCT(iii) The secondary switch is turned on with ZCS and

turned off with ZCS

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 10 When 1198781

= 1198782

= 1 and 1198783

= 1 or 0

(iv) All other components of the parallel boost converterfunctions based on this soft switching

(v) There is no additional current or voltage force on themain switches 119878

1and 1198782

(vi) There is no additional current or voltage force on thesecondary switch 119878

3

(vii) Also there is no additional current or voltage force onthe main diodes 119863

1198911and 119863

1198912

(viii) According to the ratio of the transformer a part of theresonant current is transferred to the output loadwiththe coupling inductance So there is less current stresson the secondary switch with satisfied points

(ix) At resistive load condition in the ZVT process themain switches voltage falls to zero earlier due todecreased interval time and that does not make aproblem in the ZVT process for the main switch

(x) At resistive load condition in the ZCT process themain switches body diode on state time is increasedwhen the input current is decreased However thereis no effect on the main switch turn off process withZCT

(xi) This parallel boost converter operates in high-switch-ing frequency

(xii) This converter easily controls because the main andthe auxiliary switches are connected with commonground

(xiii) Themost attractive feature of this proposed converteris using ZVT and ZCT technique

(xiv) The proposed new active snubber circuit is easilyadopted with other basic PWM converters and alsoswitching converters

(xv) Additional passive snubber circuits are not necessaryfor this proposed converter

(xvi) SIC (silicon carbide) is used in the main and auxiliarydiodes so reverse recovery problem does not arise

(xvii) Theproposed active snubber circuit is also suitable forother DC-DC converters

41 Procedure for Constructing a Proposed Converter Steps toobtain a system level modeling and simulation of proposedpower electronic converter are listed below

International Journal of Photoenergy 7

Active snubber

Main diodesMain inductors MLI

Grid

Main capacitorMPPTSolar PV

Main switches

Snubber circuit

Auxiliary

Input source

(Lf1 Lf2)

Parallel boost converter

(S1 S2)

(L1235)

switch (S3)

Figure 11 Block diagram of PV based parallel boost converter with active snubber

Table 2 Specification of parallel boost converter with activeSnubber

Main inductor 1198711198911

750 120583HMain inductor 119871

1198912750 120583H

Upper Snubber inductor 1198711198771

5 120583HLower Snubber inductor 119871

1198772(119871119898

+ 119871119889) 2 120583H

Magnetization inductor 119871119872(119871119899

+ 1198710119897) 3 120583H

Parasitic capacitor 119862119904

1 120583FSnubber capacitor 119862

11987747 nF

Output capacitor 119862119900

330 120583F450VOutput load resistance 119877 = 119877

119871530Ω

(i) Determine the state variables of the proposed powercircuit in order to write its switched state-spacemodel for example inductance current and capaci-tance voltage

(ii) Assign integer variables (ON-1 and OFF-0 state) tothe proposed power semiconductor to each switchingcircuit

(iii) Determine the conditions controlling the states ofthe proposed power semiconductors or the switchingcircuit

(iv) Assume the main operating modes apply Kirchhoff rsquosCurrent law and Kirchhoff rsquos Voltage law and combineall the required stages into a switched state-spacemodel which is the desired system-level of the pro-posed model

(v) Implement the derived equations with MATLABSimulink

(vi) Use the obtained switched space-state model todesign linear or nonlinear controllers for the pro-posed power converter

The algorithm for solving the differential equations andthe step size should be chosen before running any simulationThis step is only suitable in closed-loop simulations [21]

42 Operation of Proposed Boost Converter with Snubber Cir-cuit Theproposed PV based converter is shown in Figure 12and it is based on a dual boost circuit where the first one(switch 119878

1and choke 119871

1198911) is used asmain chock of boost con-

verter circuit and where the second one (switch 1198782and choke

1198711198912) is used to perform an active filtering The proposed

converter applies active snubber circuit for soft switchingThis snubber circuit is built on the ZVT turn on andZCT turnoff processes of the main switches Specification of proposedparallel boost converter with active snubber is in Table 2

The power from the solar flows through the two parallelpaths High efficiency was obtained by this method So asto reach soft switching (SS) for the main and the auxiliaryswitches main switches turn on with ZVT and turn off withZCT The proposed converter utilizes active snubber circuitfor SS This snubber circuit is mostly based on the ZVT turnon and ZCT turn off processes of the main switch 119871

1198772value

is limited with (119881out1198711198772

)119905rise1198782 le 119868119894max to conduct maximum

input current at the end of the auxiliary switch rise time(119905rise1198782) and119871

1198771ge 21198711198772 To turn off 119878

1with ZCT the duration

of 119905ZCT is at least longer than fall time of 1198781(119905fall1198781)119905ZCT ge

119905fall1198781 Though the main switches are in off state the controlsignal is functional to the auxiliary switch The parasiticcapacitor of the main switch should be discharged absolutelyand themain switches antiparallel diode should be turned onThe on state time of the antiparallel diode is named 119905ZVT andin this time period the gate signal of the main switch wouldbe applied So the main switch is turned on below ZVS andZCS with ZVT

Whereas the main switches are in on state and ways inputcurrent the control signal of the auxiliary switch is appliedAfter the resonant starts the resonant current should behigher than the input current to turn on the antiparallel diodeof the main switchThe on state time of the antiparallel diode(119905ZCT) has to be longer than the main switches fall time (119905

1198911198781)

After all these terms are completed while antiparallel diodeis in on state the gate signal of the main switch should becutoff to provide ZCT for the main switch Auxiliary switchturn on with ZCS and turn off with ZCSThe auxiliary switchis turned on with ZCS for the coupling inductance limits thecurrent rise speed

8 International Journal of Photoenergy

Lf1

Lf2

S1 S2

S3

D2

Ld

Lm

LR1

D1

Ln

RLoad

Co

Lo1 D4

Df1

Df2

D3

CR

PVArray

Figure 12 Circuit diagram of PV based parallel boost converter with active snubber with resistive load

The current passing through the coupling inductancemust be partial to conductmaximum input current at the endof the auxiliary switch rise time (119905

1199031198783) So the turn on process

of the auxiliary switch with ZCS is offered To turn off theauxiliary switch with ZCS though the auxiliary switch is inon state the current passing through the switch should fallto zero with a new resonant Then the control signal can becutoff If 119862

119878is ignored 119871

1198771value should be two times added

with 1198711198772

to make the auxiliary switch current fall to zero Asthe current cannot stay at zero as long as the auxiliary switchfall time (119905

1198911198783) the auxiliary switch is turned off nearly with

ZCSThe proposed Simulink topology is shown in Figure 13

The inductors 1198711198911

and 1198711198912

have the similar values the diodes1198631198911-1198631198912

are at the same type and the same guess was for theswitches (119878

1amp 1198782) All the inductors have individual switches

and they resemble paralleling of classic converters

5 Design of MLI Module

A multilevel converter is a power electronic system thatsynthesizes a desired output voltage levels from theDC inputssupply Compared with the traditional two-level voltageconverter the primary advantage of multilevel converters istheir smaller output voltage step which results in high powerquality lower harmonic components better electromagneticcompatibility and lower switching losses The functionalityverification of the simplified seven-level inverter is doneusing MATLAB simulation which is shown in Figure 14

This single-phase simplified seven-level inverter wasdeveloped using a single-phase full bridge (H-bridge)inverter two bidirectional auxiliary switches and a capac-itor voltage divider formed by 119862

1 1198622 and 119862

3 as shown

in Figure 14 The simplified multilevel inverter topology is

Table 3 Switching pattern for the single-phase seven-level inverter

1198810

1198781

1198782

1198783

1198784

1198785

1198786

119881dc 1 0 0 1 0 02119881dc3 0 0 0 1 1 0119881dc3 0 0 0 1 0 10 0 0 1 1 0 00lowast 1 1 0 0 0 0minus119881dc3 0 1 0 0 1 0minus2119881dc3 0 1 0 0 0 1minus119881dc 0 1 1 0 0 0

significantly advantageous over other topologies The advan-tages of simplified topology are requirement of less powerswitch power diodes and less capacitors for this inverterPhotovoltaic arrays were connected to the inverter via a DC-DC SEPIC converter The power generated by the inverter isto be delivered to the power network so the utility grid ratherthan a load was used The DC-DC SEPIC converter wasrequired because the PV arrays had a voltage that was lowerthan the grid voltage High DC bus voltages are necessary toensure that power flows from the PV arrays to the grid Afiltering inductance 119871

119891was used to filter the current injected

into the grid Proper switching of the inverter can produceseven levels of output-voltage (119881dc 2119881dc3 119881dc3 0 0

lowastminus119881dc3 minus2119881dc3 minus119881dc) from the DC supply voltage Table 3shows the switching pattern for the single-phase simplifiedseven-level inverter

6 Grid-Connected Solar Power System

The modelling and simulation of PV MPPT CPWMSEPICconverter simplified seven-level MLI and controller had

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

International Journal of Photoenergy 5

Reset

Relational

Randomnumber

Discrete-time

Chaotic PWM

Chaos carrier

integrator1

A1

1z

operator1

Unit delay1

03ge

ge

Constant2

K Ts

z minus 1

Figure 5 Chaotic PWM pulse generation

Figure 6 Hardware setup

Figure 7 Chaotic PWM

24 Experimental Setup Standalone PV System Figure 6shows the experimental setup of the proposed SEPICconverter-based MPPT for solar PV module which is con-stituted by a power stage and a control circuit The powerstage includes an inductor 119871

1 1198712 capacitor 119862

1 1198622 a switch

119878 a load resistance and a solar PV module (L1235-37Wp)The analog chaotic carrier is generated based on the hardwareoutput of CPWM is in Figure 7

3 Mathematical Model for Parallel BoostConverter with Active Snubber Circuit

Figure 12 represents the circuit diagram of the parallel boostconverter with active snubber It consists of five inductors119871119891119894 1198711198912 1198711198771 1198711198772 119871119899and three capacitors 119862

119904 119862119903 119862119900 119881119892

and 119881119900represents supply and output voltage respectively

119878 (1198781 1198782) is an active primary switch 119863 (119863

1198911 1198631198912

) is a free-wheeling diode 119863

119904(1198631 1198632 1198633) is a Snubber diode and 119877

119871

is the load resistance 119878 (1198781 1198782 1198783) operates at a switching fre-

quency 119891119878with duty ratio 119889

Choose the switching frequency of switches 1198781

= 1198782

=

100KHz and 1198783

= 200KHzWhen 119878

1= 1198782

= 0 and 1198783

= 1 as in Figure 8

119889119894119871119865

119889119905=

1

119871119865

[119881119892

= 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

minus 119894119871119878]

(18)

Also the switches 1198781

= 1198782

= 1198783

= 1 as in Figure 9

119889119894119871119865

119889119905=

1

119871119865

[119881119892

minus 119881119900]

119889119881119900

119889119905=

1

119862119900

[119894119871119865

minus119881119900

119877119871

]

(19)

Similarly the switches 1198781

= 1198782

= 1 and 1198783

= 1 or 0 as inFigure 10

119889119894119871119865

119889119905=

119881119892

119871119865

119889119881119900

119889119905=

1

119862119900

[minus119881119900

119877119871

]

(20)

6 International Journal of Photoenergy

Vg

minus

+

Lf1

Lf2

Co RLLs Vo

iLs

iLf

Figure 8 When 1198781

= 1198782

= 0 and 1198783

= 1

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 9 When 1198781

= 1198782

= 1198783

= 1

By using state-space averagingmethod the state equationsduring switch-on and switch-off conditions are

1

=minus (1 minus 119889

1)

119871119865

1199092

minus(1 minus 119889

2)

119871119865

1199092

+

119881119892

119871119865

2

=minus1

119877119871119862119900

1199092

+(1 minus 119889

1) 1198892

119862119900

1199091

+(1 minus 119889

1) (1 minus 119889

2)

119862119900

1199091

(21)

where 1199091and 119909

2are the moving averages of 119894

119871119865and 119881

119900

respectively

4 Proposed Parallel Boost Converter forPV Application

Figure 11 shows the BlockDiagram of PV based parallel boostconverter with active snubber It is the combination of newactive snubber circuit with parallel boost converter Threeswitches 119878

1 1198782 and 119878

3are used 119878

1and 1198782act as main switch

and 1198783acts as an auxiliary switch 119878

1and 1198782are controlled by

ZVT and ZCT respectively also 1198783is controlled by ZCSThis

circuit operates with the input of solar powerAssume both the main switches (119878

1and 119878

2) operate in

the same frequency The features of proposed parallel boostconverter are as follows

(i) All the semiconductors work with soft switching inthe proposed converter

(ii) The main switches 1198781and 119878

2turn on with ZVT and

turn off with ZCT(iii) The secondary switch is turned on with ZCS and

turned off with ZCS

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 10 When 1198781

= 1198782

= 1 and 1198783

= 1 or 0

(iv) All other components of the parallel boost converterfunctions based on this soft switching

(v) There is no additional current or voltage force on themain switches 119878

1and 1198782

(vi) There is no additional current or voltage force on thesecondary switch 119878

3

(vii) Also there is no additional current or voltage force onthe main diodes 119863

1198911and 119863

1198912

(viii) According to the ratio of the transformer a part of theresonant current is transferred to the output loadwiththe coupling inductance So there is less current stresson the secondary switch with satisfied points

(ix) At resistive load condition in the ZVT process themain switches voltage falls to zero earlier due todecreased interval time and that does not make aproblem in the ZVT process for the main switch

(x) At resistive load condition in the ZCT process themain switches body diode on state time is increasedwhen the input current is decreased However thereis no effect on the main switch turn off process withZCT

(xi) This parallel boost converter operates in high-switch-ing frequency

(xii) This converter easily controls because the main andthe auxiliary switches are connected with commonground

(xiii) Themost attractive feature of this proposed converteris using ZVT and ZCT technique

(xiv) The proposed new active snubber circuit is easilyadopted with other basic PWM converters and alsoswitching converters

(xv) Additional passive snubber circuits are not necessaryfor this proposed converter

(xvi) SIC (silicon carbide) is used in the main and auxiliarydiodes so reverse recovery problem does not arise

(xvii) Theproposed active snubber circuit is also suitable forother DC-DC converters

41 Procedure for Constructing a Proposed Converter Steps toobtain a system level modeling and simulation of proposedpower electronic converter are listed below

International Journal of Photoenergy 7

Active snubber

Main diodesMain inductors MLI

Grid

Main capacitorMPPTSolar PV

Main switches

Snubber circuit

Auxiliary

Input source

(Lf1 Lf2)

Parallel boost converter

(S1 S2)

(L1235)

switch (S3)

Figure 11 Block diagram of PV based parallel boost converter with active snubber

Table 2 Specification of parallel boost converter with activeSnubber

Main inductor 1198711198911

750 120583HMain inductor 119871

1198912750 120583H

Upper Snubber inductor 1198711198771

5 120583HLower Snubber inductor 119871

1198772(119871119898

+ 119871119889) 2 120583H

Magnetization inductor 119871119872(119871119899

+ 1198710119897) 3 120583H

Parasitic capacitor 119862119904

1 120583FSnubber capacitor 119862

11987747 nF

Output capacitor 119862119900

330 120583F450VOutput load resistance 119877 = 119877

119871530Ω

(i) Determine the state variables of the proposed powercircuit in order to write its switched state-spacemodel for example inductance current and capaci-tance voltage

(ii) Assign integer variables (ON-1 and OFF-0 state) tothe proposed power semiconductor to each switchingcircuit

(iii) Determine the conditions controlling the states ofthe proposed power semiconductors or the switchingcircuit

(iv) Assume the main operating modes apply Kirchhoff rsquosCurrent law and Kirchhoff rsquos Voltage law and combineall the required stages into a switched state-spacemodel which is the desired system-level of the pro-posed model

(v) Implement the derived equations with MATLABSimulink

(vi) Use the obtained switched space-state model todesign linear or nonlinear controllers for the pro-posed power converter

The algorithm for solving the differential equations andthe step size should be chosen before running any simulationThis step is only suitable in closed-loop simulations [21]

42 Operation of Proposed Boost Converter with Snubber Cir-cuit Theproposed PV based converter is shown in Figure 12and it is based on a dual boost circuit where the first one(switch 119878

1and choke 119871

1198911) is used asmain chock of boost con-

verter circuit and where the second one (switch 1198782and choke

1198711198912) is used to perform an active filtering The proposed

converter applies active snubber circuit for soft switchingThis snubber circuit is built on the ZVT turn on andZCT turnoff processes of the main switches Specification of proposedparallel boost converter with active snubber is in Table 2

The power from the solar flows through the two parallelpaths High efficiency was obtained by this method So asto reach soft switching (SS) for the main and the auxiliaryswitches main switches turn on with ZVT and turn off withZCT The proposed converter utilizes active snubber circuitfor SS This snubber circuit is mostly based on the ZVT turnon and ZCT turn off processes of the main switch 119871

1198772value

is limited with (119881out1198711198772

)119905rise1198782 le 119868119894max to conduct maximum

input current at the end of the auxiliary switch rise time(119905rise1198782) and119871

1198771ge 21198711198772 To turn off 119878

1with ZCT the duration

of 119905ZCT is at least longer than fall time of 1198781(119905fall1198781)119905ZCT ge

119905fall1198781 Though the main switches are in off state the controlsignal is functional to the auxiliary switch The parasiticcapacitor of the main switch should be discharged absolutelyand themain switches antiparallel diode should be turned onThe on state time of the antiparallel diode is named 119905ZVT andin this time period the gate signal of the main switch wouldbe applied So the main switch is turned on below ZVS andZCS with ZVT

Whereas the main switches are in on state and ways inputcurrent the control signal of the auxiliary switch is appliedAfter the resonant starts the resonant current should behigher than the input current to turn on the antiparallel diodeof the main switchThe on state time of the antiparallel diode(119905ZCT) has to be longer than the main switches fall time (119905

1198911198781)

After all these terms are completed while antiparallel diodeis in on state the gate signal of the main switch should becutoff to provide ZCT for the main switch Auxiliary switchturn on with ZCS and turn off with ZCSThe auxiliary switchis turned on with ZCS for the coupling inductance limits thecurrent rise speed

8 International Journal of Photoenergy

Lf1

Lf2

S1 S2

S3

D2

Ld

Lm

LR1

D1

Ln

RLoad

Co

Lo1 D4

Df1

Df2

D3

CR

PVArray

Figure 12 Circuit diagram of PV based parallel boost converter with active snubber with resistive load

The current passing through the coupling inductancemust be partial to conductmaximum input current at the endof the auxiliary switch rise time (119905

1199031198783) So the turn on process

of the auxiliary switch with ZCS is offered To turn off theauxiliary switch with ZCS though the auxiliary switch is inon state the current passing through the switch should fallto zero with a new resonant Then the control signal can becutoff If 119862

119878is ignored 119871

1198771value should be two times added

with 1198711198772

to make the auxiliary switch current fall to zero Asthe current cannot stay at zero as long as the auxiliary switchfall time (119905

1198911198783) the auxiliary switch is turned off nearly with

ZCSThe proposed Simulink topology is shown in Figure 13

The inductors 1198711198911

and 1198711198912

have the similar values the diodes1198631198911-1198631198912

are at the same type and the same guess was for theswitches (119878

1amp 1198782) All the inductors have individual switches

and they resemble paralleling of classic converters

5 Design of MLI Module

A multilevel converter is a power electronic system thatsynthesizes a desired output voltage levels from theDC inputssupply Compared with the traditional two-level voltageconverter the primary advantage of multilevel converters istheir smaller output voltage step which results in high powerquality lower harmonic components better electromagneticcompatibility and lower switching losses The functionalityverification of the simplified seven-level inverter is doneusing MATLAB simulation which is shown in Figure 14

This single-phase simplified seven-level inverter wasdeveloped using a single-phase full bridge (H-bridge)inverter two bidirectional auxiliary switches and a capac-itor voltage divider formed by 119862

1 1198622 and 119862

3 as shown

in Figure 14 The simplified multilevel inverter topology is

Table 3 Switching pattern for the single-phase seven-level inverter

1198810

1198781

1198782

1198783

1198784

1198785

1198786

119881dc 1 0 0 1 0 02119881dc3 0 0 0 1 1 0119881dc3 0 0 0 1 0 10 0 0 1 1 0 00lowast 1 1 0 0 0 0minus119881dc3 0 1 0 0 1 0minus2119881dc3 0 1 0 0 0 1minus119881dc 0 1 1 0 0 0

significantly advantageous over other topologies The advan-tages of simplified topology are requirement of less powerswitch power diodes and less capacitors for this inverterPhotovoltaic arrays were connected to the inverter via a DC-DC SEPIC converter The power generated by the inverter isto be delivered to the power network so the utility grid ratherthan a load was used The DC-DC SEPIC converter wasrequired because the PV arrays had a voltage that was lowerthan the grid voltage High DC bus voltages are necessary toensure that power flows from the PV arrays to the grid Afiltering inductance 119871

119891was used to filter the current injected

into the grid Proper switching of the inverter can produceseven levels of output-voltage (119881dc 2119881dc3 119881dc3 0 0

lowastminus119881dc3 minus2119881dc3 minus119881dc) from the DC supply voltage Table 3shows the switching pattern for the single-phase simplifiedseven-level inverter

6 Grid-Connected Solar Power System

The modelling and simulation of PV MPPT CPWMSEPICconverter simplified seven-level MLI and controller had

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

6 International Journal of Photoenergy

Vg

minus

+

Lf1

Lf2

Co RLLs Vo

iLs

iLf

Figure 8 When 1198781

= 1198782

= 0 and 1198783

= 1

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 9 When 1198781

= 1198782

= 1198783

= 1

By using state-space averagingmethod the state equationsduring switch-on and switch-off conditions are

1

=minus (1 minus 119889

1)

119871119865

1199092

minus(1 minus 119889

2)

119871119865

1199092

+

119881119892

119871119865

2

=minus1

119877119871119862119900

1199092

+(1 minus 119889

1) 1198892

119862119900

1199091

+(1 minus 119889

1) (1 minus 119889

2)

119862119900

1199091

(21)

where 1199091and 119909

2are the moving averages of 119894

119871119865and 119881

119900

respectively

4 Proposed Parallel Boost Converter forPV Application

Figure 11 shows the BlockDiagram of PV based parallel boostconverter with active snubber It is the combination of newactive snubber circuit with parallel boost converter Threeswitches 119878

1 1198782 and 119878

3are used 119878

1and 1198782act as main switch

and 1198783acts as an auxiliary switch 119878

1and 1198782are controlled by

ZVT and ZCT respectively also 1198783is controlled by ZCSThis

circuit operates with the input of solar powerAssume both the main switches (119878

1and 119878

2) operate in

the same frequency The features of proposed parallel boostconverter are as follows

(i) All the semiconductors work with soft switching inthe proposed converter

(ii) The main switches 1198781and 119878

2turn on with ZVT and

turn off with ZCT(iii) The secondary switch is turned on with ZCS and

turned off with ZCS

Vg

minus

+

Lf1

Lf2

CoRL Vo

iLf

Figure 10 When 1198781

= 1198782

= 1 and 1198783

= 1 or 0

(iv) All other components of the parallel boost converterfunctions based on this soft switching

(v) There is no additional current or voltage force on themain switches 119878

1and 1198782

(vi) There is no additional current or voltage force on thesecondary switch 119878

3

(vii) Also there is no additional current or voltage force onthe main diodes 119863

1198911and 119863

1198912

(viii) According to the ratio of the transformer a part of theresonant current is transferred to the output loadwiththe coupling inductance So there is less current stresson the secondary switch with satisfied points

(ix) At resistive load condition in the ZVT process themain switches voltage falls to zero earlier due todecreased interval time and that does not make aproblem in the ZVT process for the main switch

(x) At resistive load condition in the ZCT process themain switches body diode on state time is increasedwhen the input current is decreased However thereis no effect on the main switch turn off process withZCT

(xi) This parallel boost converter operates in high-switch-ing frequency

(xii) This converter easily controls because the main andthe auxiliary switches are connected with commonground

(xiii) Themost attractive feature of this proposed converteris using ZVT and ZCT technique

(xiv) The proposed new active snubber circuit is easilyadopted with other basic PWM converters and alsoswitching converters

(xv) Additional passive snubber circuits are not necessaryfor this proposed converter

(xvi) SIC (silicon carbide) is used in the main and auxiliarydiodes so reverse recovery problem does not arise

(xvii) Theproposed active snubber circuit is also suitable forother DC-DC converters

41 Procedure for Constructing a Proposed Converter Steps toobtain a system level modeling and simulation of proposedpower electronic converter are listed below

International Journal of Photoenergy 7

Active snubber

Main diodesMain inductors MLI

Grid

Main capacitorMPPTSolar PV

Main switches

Snubber circuit

Auxiliary

Input source

(Lf1 Lf2)

Parallel boost converter

(S1 S2)

(L1235)

switch (S3)

Figure 11 Block diagram of PV based parallel boost converter with active snubber

Table 2 Specification of parallel boost converter with activeSnubber

Main inductor 1198711198911

750 120583HMain inductor 119871

1198912750 120583H

Upper Snubber inductor 1198711198771

5 120583HLower Snubber inductor 119871

1198772(119871119898

+ 119871119889) 2 120583H

Magnetization inductor 119871119872(119871119899

+ 1198710119897) 3 120583H

Parasitic capacitor 119862119904

1 120583FSnubber capacitor 119862

11987747 nF

Output capacitor 119862119900

330 120583F450VOutput load resistance 119877 = 119877

119871530Ω

(i) Determine the state variables of the proposed powercircuit in order to write its switched state-spacemodel for example inductance current and capaci-tance voltage

(ii) Assign integer variables (ON-1 and OFF-0 state) tothe proposed power semiconductor to each switchingcircuit

(iii) Determine the conditions controlling the states ofthe proposed power semiconductors or the switchingcircuit

(iv) Assume the main operating modes apply Kirchhoff rsquosCurrent law and Kirchhoff rsquos Voltage law and combineall the required stages into a switched state-spacemodel which is the desired system-level of the pro-posed model

(v) Implement the derived equations with MATLABSimulink

(vi) Use the obtained switched space-state model todesign linear or nonlinear controllers for the pro-posed power converter

The algorithm for solving the differential equations andthe step size should be chosen before running any simulationThis step is only suitable in closed-loop simulations [21]

42 Operation of Proposed Boost Converter with Snubber Cir-cuit Theproposed PV based converter is shown in Figure 12and it is based on a dual boost circuit where the first one(switch 119878

1and choke 119871

1198911) is used asmain chock of boost con-

verter circuit and where the second one (switch 1198782and choke

1198711198912) is used to perform an active filtering The proposed

converter applies active snubber circuit for soft switchingThis snubber circuit is built on the ZVT turn on andZCT turnoff processes of the main switches Specification of proposedparallel boost converter with active snubber is in Table 2

The power from the solar flows through the two parallelpaths High efficiency was obtained by this method So asto reach soft switching (SS) for the main and the auxiliaryswitches main switches turn on with ZVT and turn off withZCT The proposed converter utilizes active snubber circuitfor SS This snubber circuit is mostly based on the ZVT turnon and ZCT turn off processes of the main switch 119871

1198772value

is limited with (119881out1198711198772

)119905rise1198782 le 119868119894max to conduct maximum

input current at the end of the auxiliary switch rise time(119905rise1198782) and119871

1198771ge 21198711198772 To turn off 119878

1with ZCT the duration

of 119905ZCT is at least longer than fall time of 1198781(119905fall1198781)119905ZCT ge

119905fall1198781 Though the main switches are in off state the controlsignal is functional to the auxiliary switch The parasiticcapacitor of the main switch should be discharged absolutelyand themain switches antiparallel diode should be turned onThe on state time of the antiparallel diode is named 119905ZVT andin this time period the gate signal of the main switch wouldbe applied So the main switch is turned on below ZVS andZCS with ZVT

Whereas the main switches are in on state and ways inputcurrent the control signal of the auxiliary switch is appliedAfter the resonant starts the resonant current should behigher than the input current to turn on the antiparallel diodeof the main switchThe on state time of the antiparallel diode(119905ZCT) has to be longer than the main switches fall time (119905

1198911198781)

After all these terms are completed while antiparallel diodeis in on state the gate signal of the main switch should becutoff to provide ZCT for the main switch Auxiliary switchturn on with ZCS and turn off with ZCSThe auxiliary switchis turned on with ZCS for the coupling inductance limits thecurrent rise speed

8 International Journal of Photoenergy

Lf1

Lf2

S1 S2

S3

D2

Ld

Lm

LR1

D1

Ln

RLoad

Co

Lo1 D4

Df1

Df2

D3

CR

PVArray

Figure 12 Circuit diagram of PV based parallel boost converter with active snubber with resistive load

The current passing through the coupling inductancemust be partial to conductmaximum input current at the endof the auxiliary switch rise time (119905

1199031198783) So the turn on process

of the auxiliary switch with ZCS is offered To turn off theauxiliary switch with ZCS though the auxiliary switch is inon state the current passing through the switch should fallto zero with a new resonant Then the control signal can becutoff If 119862

119878is ignored 119871

1198771value should be two times added

with 1198711198772

to make the auxiliary switch current fall to zero Asthe current cannot stay at zero as long as the auxiliary switchfall time (119905

1198911198783) the auxiliary switch is turned off nearly with

ZCSThe proposed Simulink topology is shown in Figure 13

The inductors 1198711198911

and 1198711198912

have the similar values the diodes1198631198911-1198631198912

are at the same type and the same guess was for theswitches (119878

1amp 1198782) All the inductors have individual switches

and they resemble paralleling of classic converters

5 Design of MLI Module

A multilevel converter is a power electronic system thatsynthesizes a desired output voltage levels from theDC inputssupply Compared with the traditional two-level voltageconverter the primary advantage of multilevel converters istheir smaller output voltage step which results in high powerquality lower harmonic components better electromagneticcompatibility and lower switching losses The functionalityverification of the simplified seven-level inverter is doneusing MATLAB simulation which is shown in Figure 14

This single-phase simplified seven-level inverter wasdeveloped using a single-phase full bridge (H-bridge)inverter two bidirectional auxiliary switches and a capac-itor voltage divider formed by 119862

1 1198622 and 119862

3 as shown

in Figure 14 The simplified multilevel inverter topology is

Table 3 Switching pattern for the single-phase seven-level inverter

1198810

1198781

1198782

1198783

1198784

1198785

1198786

119881dc 1 0 0 1 0 02119881dc3 0 0 0 1 1 0119881dc3 0 0 0 1 0 10 0 0 1 1 0 00lowast 1 1 0 0 0 0minus119881dc3 0 1 0 0 1 0minus2119881dc3 0 1 0 0 0 1minus119881dc 0 1 1 0 0 0

significantly advantageous over other topologies The advan-tages of simplified topology are requirement of less powerswitch power diodes and less capacitors for this inverterPhotovoltaic arrays were connected to the inverter via a DC-DC SEPIC converter The power generated by the inverter isto be delivered to the power network so the utility grid ratherthan a load was used The DC-DC SEPIC converter wasrequired because the PV arrays had a voltage that was lowerthan the grid voltage High DC bus voltages are necessary toensure that power flows from the PV arrays to the grid Afiltering inductance 119871

119891was used to filter the current injected

into the grid Proper switching of the inverter can produceseven levels of output-voltage (119881dc 2119881dc3 119881dc3 0 0

lowastminus119881dc3 minus2119881dc3 minus119881dc) from the DC supply voltage Table 3shows the switching pattern for the single-phase simplifiedseven-level inverter

6 Grid-Connected Solar Power System

The modelling and simulation of PV MPPT CPWMSEPICconverter simplified seven-level MLI and controller had

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

International Journal of Photoenergy 7

Active snubber

Main diodesMain inductors MLI

Grid

Main capacitorMPPTSolar PV

Main switches

Snubber circuit

Auxiliary

Input source

(Lf1 Lf2)

Parallel boost converter

(S1 S2)

(L1235)

switch (S3)

Figure 11 Block diagram of PV based parallel boost converter with active snubber

Table 2 Specification of parallel boost converter with activeSnubber

Main inductor 1198711198911

750 120583HMain inductor 119871

1198912750 120583H

Upper Snubber inductor 1198711198771

5 120583HLower Snubber inductor 119871

1198772(119871119898

+ 119871119889) 2 120583H

Magnetization inductor 119871119872(119871119899

+ 1198710119897) 3 120583H

Parasitic capacitor 119862119904

1 120583FSnubber capacitor 119862

11987747 nF

Output capacitor 119862119900

330 120583F450VOutput load resistance 119877 = 119877

119871530Ω

(i) Determine the state variables of the proposed powercircuit in order to write its switched state-spacemodel for example inductance current and capaci-tance voltage

(ii) Assign integer variables (ON-1 and OFF-0 state) tothe proposed power semiconductor to each switchingcircuit

(iii) Determine the conditions controlling the states ofthe proposed power semiconductors or the switchingcircuit

(iv) Assume the main operating modes apply Kirchhoff rsquosCurrent law and Kirchhoff rsquos Voltage law and combineall the required stages into a switched state-spacemodel which is the desired system-level of the pro-posed model

(v) Implement the derived equations with MATLABSimulink

(vi) Use the obtained switched space-state model todesign linear or nonlinear controllers for the pro-posed power converter

The algorithm for solving the differential equations andthe step size should be chosen before running any simulationThis step is only suitable in closed-loop simulations [21]

42 Operation of Proposed Boost Converter with Snubber Cir-cuit Theproposed PV based converter is shown in Figure 12and it is based on a dual boost circuit where the first one(switch 119878

1and choke 119871

1198911) is used asmain chock of boost con-

verter circuit and where the second one (switch 1198782and choke

1198711198912) is used to perform an active filtering The proposed

converter applies active snubber circuit for soft switchingThis snubber circuit is built on the ZVT turn on andZCT turnoff processes of the main switches Specification of proposedparallel boost converter with active snubber is in Table 2

The power from the solar flows through the two parallelpaths High efficiency was obtained by this method So asto reach soft switching (SS) for the main and the auxiliaryswitches main switches turn on with ZVT and turn off withZCT The proposed converter utilizes active snubber circuitfor SS This snubber circuit is mostly based on the ZVT turnon and ZCT turn off processes of the main switch 119871

1198772value

is limited with (119881out1198711198772

)119905rise1198782 le 119868119894max to conduct maximum

input current at the end of the auxiliary switch rise time(119905rise1198782) and119871

1198771ge 21198711198772 To turn off 119878

1with ZCT the duration

of 119905ZCT is at least longer than fall time of 1198781(119905fall1198781)119905ZCT ge

119905fall1198781 Though the main switches are in off state the controlsignal is functional to the auxiliary switch The parasiticcapacitor of the main switch should be discharged absolutelyand themain switches antiparallel diode should be turned onThe on state time of the antiparallel diode is named 119905ZVT andin this time period the gate signal of the main switch wouldbe applied So the main switch is turned on below ZVS andZCS with ZVT

Whereas the main switches are in on state and ways inputcurrent the control signal of the auxiliary switch is appliedAfter the resonant starts the resonant current should behigher than the input current to turn on the antiparallel diodeof the main switchThe on state time of the antiparallel diode(119905ZCT) has to be longer than the main switches fall time (119905

1198911198781)

After all these terms are completed while antiparallel diodeis in on state the gate signal of the main switch should becutoff to provide ZCT for the main switch Auxiliary switchturn on with ZCS and turn off with ZCSThe auxiliary switchis turned on with ZCS for the coupling inductance limits thecurrent rise speed

8 International Journal of Photoenergy

Lf1

Lf2

S1 S2

S3

D2

Ld

Lm

LR1

D1

Ln

RLoad

Co

Lo1 D4

Df1

Df2

D3

CR

PVArray

Figure 12 Circuit diagram of PV based parallel boost converter with active snubber with resistive load

The current passing through the coupling inductancemust be partial to conductmaximum input current at the endof the auxiliary switch rise time (119905

1199031198783) So the turn on process

of the auxiliary switch with ZCS is offered To turn off theauxiliary switch with ZCS though the auxiliary switch is inon state the current passing through the switch should fallto zero with a new resonant Then the control signal can becutoff If 119862

119878is ignored 119871

1198771value should be two times added

with 1198711198772

to make the auxiliary switch current fall to zero Asthe current cannot stay at zero as long as the auxiliary switchfall time (119905

1198911198783) the auxiliary switch is turned off nearly with

ZCSThe proposed Simulink topology is shown in Figure 13

The inductors 1198711198911

and 1198711198912

have the similar values the diodes1198631198911-1198631198912

are at the same type and the same guess was for theswitches (119878

1amp 1198782) All the inductors have individual switches

and they resemble paralleling of classic converters

5 Design of MLI Module

A multilevel converter is a power electronic system thatsynthesizes a desired output voltage levels from theDC inputssupply Compared with the traditional two-level voltageconverter the primary advantage of multilevel converters istheir smaller output voltage step which results in high powerquality lower harmonic components better electromagneticcompatibility and lower switching losses The functionalityverification of the simplified seven-level inverter is doneusing MATLAB simulation which is shown in Figure 14

This single-phase simplified seven-level inverter wasdeveloped using a single-phase full bridge (H-bridge)inverter two bidirectional auxiliary switches and a capac-itor voltage divider formed by 119862

1 1198622 and 119862

3 as shown

in Figure 14 The simplified multilevel inverter topology is

Table 3 Switching pattern for the single-phase seven-level inverter

1198810

1198781

1198782

1198783

1198784

1198785

1198786

119881dc 1 0 0 1 0 02119881dc3 0 0 0 1 1 0119881dc3 0 0 0 1 0 10 0 0 1 1 0 00lowast 1 1 0 0 0 0minus119881dc3 0 1 0 0 1 0minus2119881dc3 0 1 0 0 0 1minus119881dc 0 1 1 0 0 0

significantly advantageous over other topologies The advan-tages of simplified topology are requirement of less powerswitch power diodes and less capacitors for this inverterPhotovoltaic arrays were connected to the inverter via a DC-DC SEPIC converter The power generated by the inverter isto be delivered to the power network so the utility grid ratherthan a load was used The DC-DC SEPIC converter wasrequired because the PV arrays had a voltage that was lowerthan the grid voltage High DC bus voltages are necessary toensure that power flows from the PV arrays to the grid Afiltering inductance 119871

119891was used to filter the current injected

into the grid Proper switching of the inverter can produceseven levels of output-voltage (119881dc 2119881dc3 119881dc3 0 0

lowastminus119881dc3 minus2119881dc3 minus119881dc) from the DC supply voltage Table 3shows the switching pattern for the single-phase simplifiedseven-level inverter

6 Grid-Connected Solar Power System

The modelling and simulation of PV MPPT CPWMSEPICconverter simplified seven-level MLI and controller had

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

8 International Journal of Photoenergy

Lf1

Lf2

S1 S2

S3

D2

Ld

Lm

LR1

D1

Ln

RLoad

Co

Lo1 D4

Df1

Df2

D3

CR

PVArray

Figure 12 Circuit diagram of PV based parallel boost converter with active snubber with resistive load

The current passing through the coupling inductancemust be partial to conductmaximum input current at the endof the auxiliary switch rise time (119905

1199031198783) So the turn on process

of the auxiliary switch with ZCS is offered To turn off theauxiliary switch with ZCS though the auxiliary switch is inon state the current passing through the switch should fallto zero with a new resonant Then the control signal can becutoff If 119862

119878is ignored 119871

1198771value should be two times added

with 1198711198772

to make the auxiliary switch current fall to zero Asthe current cannot stay at zero as long as the auxiliary switchfall time (119905

1198911198783) the auxiliary switch is turned off nearly with

ZCSThe proposed Simulink topology is shown in Figure 13

The inductors 1198711198911

and 1198711198912

have the similar values the diodes1198631198911-1198631198912

are at the same type and the same guess was for theswitches (119878

1amp 1198782) All the inductors have individual switches

and they resemble paralleling of classic converters

5 Design of MLI Module

A multilevel converter is a power electronic system thatsynthesizes a desired output voltage levels from theDC inputssupply Compared with the traditional two-level voltageconverter the primary advantage of multilevel converters istheir smaller output voltage step which results in high powerquality lower harmonic components better electromagneticcompatibility and lower switching losses The functionalityverification of the simplified seven-level inverter is doneusing MATLAB simulation which is shown in Figure 14

This single-phase simplified seven-level inverter wasdeveloped using a single-phase full bridge (H-bridge)inverter two bidirectional auxiliary switches and a capac-itor voltage divider formed by 119862

1 1198622 and 119862

3 as shown

in Figure 14 The simplified multilevel inverter topology is

Table 3 Switching pattern for the single-phase seven-level inverter

1198810

1198781

1198782

1198783

1198784

1198785

1198786

119881dc 1 0 0 1 0 02119881dc3 0 0 0 1 1 0119881dc3 0 0 0 1 0 10 0 0 1 1 0 00lowast 1 1 0 0 0 0minus119881dc3 0 1 0 0 1 0minus2119881dc3 0 1 0 0 0 1minus119881dc 0 1 1 0 0 0

significantly advantageous over other topologies The advan-tages of simplified topology are requirement of less powerswitch power diodes and less capacitors for this inverterPhotovoltaic arrays were connected to the inverter via a DC-DC SEPIC converter The power generated by the inverter isto be delivered to the power network so the utility grid ratherthan a load was used The DC-DC SEPIC converter wasrequired because the PV arrays had a voltage that was lowerthan the grid voltage High DC bus voltages are necessary toensure that power flows from the PV arrays to the grid Afiltering inductance 119871

119891was used to filter the current injected

into the grid Proper switching of the inverter can produceseven levels of output-voltage (119881dc 2119881dc3 119881dc3 0 0

lowastminus119881dc3 minus2119881dc3 minus119881dc) from the DC supply voltage Table 3shows the switching pattern for the single-phase simplifiedseven-level inverter

6 Grid-Connected Solar Power System

The modelling and simulation of PV MPPT CPWMSEPICconverter simplified seven-level MLI and controller had

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

International Journal of Photoenergy 9

Discrete

Powergui

0

Volt

Power

Current

Duty

Boost

vs1 is4

Mean

Mean

Mean value1

solar

Mean value2

Output1Output2

Current measurement

Output4

i

minus

+

minus

+

+

+

++ +

+

+

minus+

s Display

Lf1

Lf

IGBTdiode

g

g

c

c

E

E

L

Pulse generator2

Mosfet

Display1

Transfer Fcn1

isolation

cycle

pwm

panel

Pulse

Pulse

generator3

generator1

IGBTdiode 1R

minus+

minus+

Multilevel inverter

Subsystem1

s = 24e minus 05s

C1C0

LO1

sg D

1

den(s)

PV current3

Figure 13 Simulink model of proposed PV based parallel boost converter with active snubber circuit with MLI

+

1

2

Out1

Out1

Out1 Out1

Step1Gain

1

1

V

I P Q

Mag V I

i

Total powerf(u)s

Dg

sDg

sDg

sDg

sDg

2

minus

minus

++

+

+

+

++ +

+

sDg

g

minus

iminus+

C1

C2

C3

P5

P6

D1

D3

D5

D7

M6

M5

D2

D4

D6

D8

M1

M3

P3

P1

P4

P2

M2

M4

+

Figure 14 Simulated model for seven-level inverter

been carried out in MATLAB Simulink environment Thebasic block diagram of reliable high efficient grid-connectedsolar power system has been shown in Figure 15

The grid-connected PV system consists ofMPPT trackingusing SEPIC converter which is used to track the maximumvoltage The tracked voltage is boosted in to 325V A simpli-fied seven-levelMLI is designed to convert into anAC voltagewith seven levels which should connect to gridThe simulatedresults for the MLI output are in Figures 16 and 17

7 Results and Discussions

A modular solar PV based DC-DC converter using parallelboost converter with active filter of the proposed systemis simulated using MATLAB Simulink program The wave-forms of parallel boost converter voltage and MLI filteredoutput voltage is shown in Figures 18 and 19 The controlsignals of the switches are shown in Figures 20 and 21respectively The simulation results show the proposed PVbased soft switched parallel boost DC-DC converter hasthe proper response The detailed comparison of SEPIC andparallel boost converter is in Table 4

Table 4 Comparison of SEPIC and parallel boost converter

Parameters SEPIC converter Parallel boost converterDuty cycle 45 47No of switches 7 9Input 148 148Output 325V 448VEfficiency 9215 987

8 Conclusion

The behaviour of solar module (L1235-37Wp) is studied Themaximum power is extracted from solar PV module usingCPWM and PWM for different converters The spectrumperformance is improved when CPWM control is used forMPPT purposes The performance of MLI is studied and theproto type model of MLI is carried out The main objectiveof this research was to improve efficiency of the solar PVbased parallel boost converter and reduce the switchinglosses Simulations were initially done for conventional boostconverter with snubber circuit The changes in the inputcurrent waveform were obtained A parallel boost converter

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

10 International Journal of Photoenergy

MPPT technique

CPWM SEPIC converter

Controller

multilevel inverter

Utility gridSun7 levels

Figure 15 Block diagram of reliable high efficient grid-connected solar power system

50

40

30

20

10

0

minus10

minus20

minus30

minus40

Curr

ent

Time0 05 1 15

Time offset 0

Figure 16 MLI output current

300

200

100

0

Volta

ge

minus100

minus200

minus300

Time0 05 1 15

Time offset 0

Figure 17 MLI output voltage

475

470

465

460

455

450

445

4400 002 004 006 008 01 012 014 016 018 02

Time offset 0

Figure 18 Parallel boost converter output voltage

800

600

400

200

0

minus200

minus400

minus600

minus8000 01 102 03 04 05 06 07 08 09

Time offset 0

Figure 19 MLI filtered output voltage (119881119900)

5505004504003503002502001501005000 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 20 Control signals of switches 1198781and 119878

2

600

500

400

300

200

100

00 02 04 06 08 1 12 14 16

times10minus3

Time offset 0

Figure 21 Control signals of switch 1198783

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

International Journal of Photoenergy 11

was designed with soft switching which is provided by theactive snubber circuit The main switches and all the othersemiconductors were switched by ZVT and ZCT techniquesThe active snubber circuit was applied to the parallel boostconverter which is fed by solar input line This latest con-verter was achievedwith 148V input Due to themain and theauxiliary switches have a common ground the converter wascontrolled easilyTheproposednewactive snubber circuit canbe simply functional to the further basic PWM convertersand to all switching converters thereby increasing efficiencyand improving output voltage

Conflict of Interests

The authors declare that there is no conflict of interestsregarding the publication of this paper

References

[1] J A Gow and C D Manning ldquoDevelopment of a photovoltaicarray model for use in power-electronics simulation studiesrdquoIEE Proceedings vol 146 no 2 pp 193ndash200 1999

[2] H Patel and V Agarwal ldquoMATLAB-based modeling to studythe effects of partial shading on PV array characteristicsrdquo IEEETransactions on Energy Conversion vol 23 no 1 pp 302ndash3102008

[3] M G Villalva J R Gazoli and E R Filho ldquoComprehensiveapproach to modeling and simulation of photovoltaic arraysrdquoIEEE Transactions on Power Electronics vol 24 no 5 pp 1198ndash1208 2009

[4] GWalker ldquoEvaluatingMPPT converter topologies using amat-lab PVmodelrdquo Journal of Electrical and Electronics Engineeringvol 21 no 1 pp 49ndash56 2001

[5] H S-H Chung K K Tse S Y Ron Hui C M Mok and MT Ho ldquoA novel maximum power point tracking technique forsolar panels using a SEPIC or Cuk converterrdquo IEEE Transactionson Power Electronics vol 18 no 3 pp 717ndash724 2003

[6] M Veerachary ldquoPower tracking for nonlinear PV sourceswith coupled inductor SEPIC converterrdquo IEEE Transactions onAerospace and Electronic Systems vol 41 no 3 pp 1019ndash10292005

[7] K K Tse BM T Ho H S-H Chung and S Y R Hui ldquoA com-parative study of maximum-power-point trackers for photo-voltaic panels using switching-frequency modulation schemerdquoIEEE Transactions on Industrial Electronics vol 51 no 2 pp410ndash418 2004

[8] K K Tse M T Ho H S-H Chung and S Y R Hui ldquoA novelmaximum power point tracker for PV panels using switchingfrequencymodulationrdquo IEEETransactions on Power Electronicsvol 17 no 6 pp 980ndash989 2002

[9] M H Taghvaee M A M Radzi S M Moosavain H Hizamand M Hamiruce Marhaban ldquoA current and future study onnon-isolated DC-DC converters for photovoltaic applicationsrdquoRenewable and Sustainable Energy Reviews vol 17 pp 216ndash2272013

[10] A Safari and SMekhilef ldquoSimulation and hardware implemen-tation of incremental conductance MPPT with direct controlmethod using cuk converterrdquo IEEE Transactions on IndustrialElectronics vol 58 no 4 pp 1154ndash1161 2011

[11] H Li Z Li B Zhang F Wang N Tan and W A HalangldquoDesign of analogue chaotic PWM for EMI suppressionrdquo IEEE

Transactions on Electromagnetic Compatibility vol 52 no 4 pp1001ndash1007 2010

[12] H Li W K S Tang Z Li and W A Halang ldquoA chaotic peakcurrent-mode boost converter for EMI reduction and ripplesuppressionrdquo IEEE Transactions on Circuits and Systems II vol55 no 8 pp 763ndash767 2008

[13] Z Wang K T Chau and C Liu ldquoImprovement of electromag-netic compatibility of motor drives using chaotic PWMrdquo IEEETransactions on Magnetics vol 43 no 6 pp 2612ndash2614 2007

[14] S-Y Tseng andH-YWang ldquoAphotovoltaic power systemusinga high step-up converter forDC load applicationsrdquoEnergies vol6 pp 1068ndash1100 2013

[15] V G Agelidis and M Calais ldquoApplication specific harmonicperformance evaluation of multicarrier PWM techniquesrdquo inProceedings of the 29thAnnual IEEEPower Electronics SpecialistsConference (PESC rsquo98) pp 172ndash178 1998

[16] Y Cheng C Qian M L Crow S Pekarek and S Atcitty ldquoAcomparison of diode-clamped and cascadedmultilevel convert-ers for a STATCOMwith energy storagerdquo IEEE Transactions onIndustrial Electronics vol 53 no 5 pp 1512ndash1521 2006

[17] L Zhang K Sun Y Xing L Feng and H Ge ldquoAmodular grid-connected photovoltaic generation system based on DC busrdquoIEEE Transactions on Power Electronics vol 26 no 2 pp 523ndash531 2011

[18] M E Ropp and S Gonzalez ldquoDevelopment of a MATLABsimulink model of a single-phase grid-connected photovoltaicsystemrdquo IEEE Transactions on Energy Conversion vol 24 no 1pp 195ndash202 2009

[19] N A Rahim K Chaniago and J Selvaraj ldquoSingle-phase seven-level grid-connected inverter for photovoltaic systemrdquo IEEETransactions on Industrial Electronics vol 58 no 6 pp 2435ndash2443 2011

[20] H S Patel and R G Hoft ldquoGeneralized techniques of harmonicelimination and voltage control in thyristor invertersmdash1 har-monic eliminationrdquo IEEETransactions on Industry Applicationsvol IA-9 no 3 pp 310ndash317 1973

[21] T Esram andP L Chapman ldquoComparison of photovoltaic arraymaximum power point tracking techniquesrdquo IEEE Transactionson Energy Conversion vol 22 no 2 pp 439ndash449 2007

[22] E J Duran M Galan Sidrach-de-Cardona and J M AndujarldquoMeasuring the I-V curve of photovoltaic generators-analyzingdifferent DC-DC converter topologiesrdquo IEEE Industrial Elec-tronics Magazine pp 4ndash14 2009

[23] J L Santos F Antunes A Chehab and C Cruz ldquoA maximumpower point tracker for PV systems using a high performanceboost converterrdquo Solar Energy vol 80 no 7 pp 772ndash778 2006

[24] W Jiang and B Fahimi ldquoActive current sharing and sourcemanagement in fuel cellbattery hybrid power systemrdquo IEEETransactions on Industrial Electronics vol 57 no 2 pp 752ndash7612010

[25] M Bhatnagar and B J Baliga ldquoComparison of 6H-SiC 3C-SiC and Si for power devicesrdquo IEEE Transactions on ElectronDevices vol 40 no 3 pp 645ndash655 1993

[26] Q Zhang R Callanan M K Das S-H Ryu A K Agarwaland J W Palmour ldquoSiC power devices for microgridsrdquo IEEETransactions on Power Electronics vol 25 no 12 pp 2889ndash28962010

[27] A Elasser M H Kheraluwala M Ghezzo et al ldquoA comparativeevaluation of new silicon carbide diodes and state-of-the-artsilicon diodes for power electronic applicationsrdquo IEEE Transac-tions on Industry Applications vol 39 no 4 pp 915ndash921 2003

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

12 International Journal of Photoenergy

[28] M M Hernando A Fernandez J Garcıa D G Lamar and MRascon ldquoComparing Si and SiC diode performance in commer-cial AC-to-DC rectifiers with power-factor correctionrdquo IEEETransactions on Industrial Electronics vol 53 no 2 pp 705ndash7072006

[29] B Ozpineci and L M Tolbert ldquoCharacterization of SiC Schot-tky diodes at different temperaturesrdquo IEEE Power ElectronicsLetters vol 1 no 2 pp 54ndash57 2003

[30] G Spiazzi S Buso M Citron M Corradin and R PierobonldquoPerformance evaluation of a Schottky SiC power diode in aboost PFC applicationrdquo IEEE Transactions on Power Electronicsvol 18 no 6 pp 1249ndash1253 2003

[31] A M Abou-Alfotouh A V Radun H-R Chang and C Win-terhalter ldquoA 1-MHz hard-switched silicon carbide DC-DC con-verterrdquo IEEE Transactions on Power Electronics vol 21 no 4 pp880ndash889 2006

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of

Submit your manuscripts athttpwwwhindawicom

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Inorganic ChemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

International Journal ofPhotoenergy

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Carbohydrate Chemistry

International Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Advances in

Physical Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom

Analytical Methods in Chemistry

Journal of

Volume 2014

Bioinorganic Chemistry and ApplicationsHindawi Publishing Corporationhttpwwwhindawicom Volume 2014

SpectroscopyInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

The Scientific World JournalHindawi Publishing Corporation httpwwwhindawicom Volume 2014

Medicinal ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Chromatography Research International

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Applied ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Theoretical ChemistryJournal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Spectroscopy

Analytical ChemistryInternational Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Journal of

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Quantum Chemistry

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

Organic Chemistry International

ElectrochemistryInternational Journal of

Hindawi Publishing Corporation httpwwwhindawicom Volume 2014

Hindawi Publishing Corporationhttpwwwhindawicom Volume 2014

CatalystsJournal of