A Quasi-Z-Source Direct Matrix Converter Feeding a Vector Controlled Induction Motor Drive

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This article has been accepted for publication in a future issue of this journal, but has not been fully edited. Content may change prior to final publication. Citation information: DOI10.1109/JESTPE.2014.2309979, IEEE Journal of Emerging and Selected Topics in Power Electronics

A Quasi-Z-Source Direct Matrix Converter Feeding AVector Controlled Induction Motor Drive

Omar Ellabban, Senior Member, IEEE, Haitham Abu-Rub, Senior Member, IEEE and Ge Baoming, Member, IEEE

Abstract––This paper proposes a novel four-quadrant vectorcontrolled induction motor (IM) adjustable speed drive (ASD)system based on a recently proposed matrix converter topologycalled quasi-Z-source direct matrix converter (QZSDMC). TheQZSDMC is formed by cascading the quasi-Z-source impedancenetwork and the conventional direct matrix converter (DMC).The QZSDMC can provide buck-boost operation with voltagetransfer ratio controlled by controlling the shoot-through dutyratio and bidirectional operation capability. The control strategy,which is based on the indirect field oriented control (IFOC)algorithm, is able to control the motor speed from zero to therated value under full load condition during motoring andregenerating operation modes. The operating principle of theproposed system are presented in detail. The simulation and thereal-time implementation results, using dSPACE 1103ControlDesk, validate the high-performance of the proposedfour-quadrants IM-ASD based on QZSDMC system. Theproposed four-quadrant vector controlled IM-ASD system basedon the QZSDMC topology overcomes the voltage gain limitationof the traditional DMC and achieves buck and boost condition infour-quadrant modes with reduced number of switches, thereforeachieving low cost, high efficiency, and reliability, compared toback-to-back converter.

Keywords–– Z-source converter, Quasi-Z-source converter,direct matrix converter, quasi-Z-source direct matrix converter,induction motor, indirect field oriented control.

Nomenclature

ASD Adjustable speed driveBQZSDMC Boost factor for the QZSDMCBZSDMC Boost factor for the ZSDMCCa1, Ca2, Cb1, Cb2,Cc1, Cc2=C QZS-network capacitances (F)

Cf Input filter capacitance (H)CMRFC Cascade matrix-reactance frequency converterD Shoot-through duty ratio (%)

DhShoot-through duty ratio in half carrier cycle(%)

DMC Direct matrix converterF IM Friction coefficient (N.m.s)Fs QZSDMC switching frequency (Hz)G QZSDMC voltage gainidr, iqr dq axes rotor current components (A)IFOC Indirect field oriented controlIM Induction motorIMC Indirect matrix converter

IMRFC Integrated matrix-reactance frequencyconverter

J IM Inertia (kg.m2)Kis Speed controller integral gain constantKii Current controller integral gain constantKps Speed controller proportional gain constantKpi Current controller proportional gain constantLa1, La2, Lb1, Lb2, Lc1,Lc2=L QZS-network inductance (H)

Lf Input filter inductance (F)Llr IM Stator inductance (H)Lls IM Stator inductance (H)Lm IM Mutual inductance (H)M Modulation index (%)MC Matrix converterMRFC Matrix-reactance frequency converter

NST Non-shoot-throughp IM No. of polesPWM Pulse width modulationQZSC Quasi-Z-source converterQZSDMC Quasi-Z-source direct matrix converterRf Input filter resistance (Ω)Rr IM Rotor resistance (Ω)Rs IM Stator resistance (Ω)S0 Gate signal for the switches Sa, Sb, ScSA, SB, SC Three PWM pulse sequencesSa, Sb, Sc=S0 QZS-network bidirectional switchesSAa, SAb, SAc, SBa, SBb,SBc, SCa, SCb, SCc

QZSDMC nine switching signals

ST Shoot-throughSx1, Sy1, Sz1 Top voltage envelope indicatorsSx2, Sy2, Sz2 Bottom voltage envelope indicatorsT* IM torque reference (N.m)T0 Shoot-through time interval (s)T1 Non-shoot-through time interval (s)THD Total Harmonic distortionTs Switching cycle (s)

vA, vB, vCQZSDMC three phase output voltagereferences (pu)

va, vb, vcQZSDMC three phase input voltage references(pu)

vdr, vqr dq axes stator voltage components(V)vi Input voltage amplitude (V)vo Output voltage amplitude (V)VSI Voltage-source inverter

ymax, yminTop and bottom envelopes of the inputvoltages, respectively

ZSC Z-source converterZSDMC Z-source direct matrix converterζ Damping ratioθe IM rotor flux angle (rad)λdr, λqr dq axes rotor flux components (Wb)λr

* IM rotor flux reference (Wb)σ IM leakage factorωe IM electric speed (rad/s)ωn System natural frequency (rad)ωr IM rotor speed (rad/s)ωsl Slip frequency (rad/s)

I. INTRODUCTION

The use of variable speed motor drives is a growingtrend in industrial and automotive applications,guaranteeing high efficiency, increased energy saving andhigher versatility and flexibility [1]. The back-to-backconverter, which is formed by tying two voltage-sourceinverter (VSI) bridges together at their shared dc-link, iscommonly applied in many motor drive applications. Oneof the converters operates in the rectifying mode, while theother converter operates in the inverting mode. The dc-linkvoltage must be higher than the peak line-to-line voltage toachieve full control of the motor torque [2], [3]. Despitebeing a well-proven topology, the back-to-back converterstill has limitations since it requires a large capacitor in thedc link and a heavy filter inductor at the input terminals.The dc-link capacitor is a critical component, especially inhigh-power or high-voltage applications, since it is largeand expensive component. Further, it has a limited servicelifetime, and is well-known to be a primary source of



failure in most converters [4]. The source-side inductorsare also a burden to the system; their size is typically 20%-40% of the system size when operating at a switchingfrequency of several kilohertz. Furthermore, the back-to-back topology is sensitive towards electromagneticinterference and other sources of noises that canaccidentally turn ON two switches from the same phaseleg, causing a short circuit fault in turn. Thus, thedrawbacks of conventional back-to-back converters arehigh cost, large size, heavy weight, relatively high energylosses, and sensitivity toward electromagnetic interference[3].

The matrix converter is an attractive alternative to theback-to-back converter because it can convert an ACvoltage directly into an AC output voltage of variableamplitude and frequency without the need for anintermediate dc-link and capacitor. Furthermore, itprovides bidirectional power flow, sinusoidal input/outputcurrents, controllable input power factor, and has compactdesign. The volume savings of a matrix convertercompared to a back-to-back converter has been estimatedto be a factor of three [3]. The large dc-link capacitor andlarge input inductors of the back-to-back converter arereplaced by small input filter with capacitors and inductorsin the matrix converter. Furthermore, because of a highintegration capability and higher reliability of thesemiconductor devices, the matrix converter topology isbetter solution for extreme temperatures and criticalvolume/weight applications [5].

Matrix converters can be divided into two categories:the direct matrix converter and the indirect matrixconverter, as indicated in Fig. 1. The DMC performs thevoltage and current conversion in one stage (direct) powerconversion while the IMC features a two-stage (indirect)power conversion. The DMC and IMC circuit topologiesare equivalent in their basic functionality. The difference inthe categories results from a difference in loading of thesemiconductors and a different commutation scheme. TheIMC has a simpler commutation due to its two-stagestructure, however, this is achieved at the expense of moreseries-connected power devices in the current path, whichresults in a higher semiconductor losses and typically alower achievable efficiency compared with the DMC.However, the differences between the controlperformances of DMC and IMC are quite negligible inpractice. Therefore, the DMC will be investigated withinthe current work as a candidate topology to achieve highestconversion efficiency [6].

Fig. 1. Direct (a) and indirect (b) matrix converter topology.

For all these attractive properties the matrix converterhas not yet gained much attention in the industry due to itsseveral unsolved problems. The most critical problem isthe reduced voltage transfer ratio, which is defined as theratio between the output voltage and the input voltage, and

has been constrained to 0.866 when using linearmodulation [5] . Several researches on the over-modulationhave been carried out to overcome the problem of lowvoltage transfer ratio. However, the over-modulation canonly be achieved at the expense of the quality of bothoutput voltage and input current [7].

Improving the voltage transfer ratio is an importantresearch topic. One easy solution is to connect atransformer between the power supply and the MC.However, the mains frequency transformer is bulky,expensive and affects the system efficiency. Other solutionis to use a matrix-reactance frequency converter (MRFC),which consists of a MC and a AC chopper, and has avoltage transfer ratio greater than one. The MRFCconverter is categorized into two groups: the integrated andcascade matrix-reactance frequency converters, as shownin Fig. 2 [8]. Unfortunately, the IMRFC typology hasseveral disadvantages. First, the control algorithm iscomplicated due to the required synchronization betweenthe MC and the AC chopper. Second, the voltage transferratio strongly dependents on the circuit and the loadparameters. Finally, the input power factor is lower thanother MCs even for a purely resistive load. The CMRFCtopology has less passive components compared by theIMRFC topology; however, it has limited voltage gain,complicated damping control of the input current anddisturbed output current.

(a) IMRFC (b) CMRFCFig. 2 Integrated (a) and cascade (b) matrix-reactance frequency

converters topologies

The Z-source converter, as shown in Fig. 3-a, is aninnovative power electronics converter technologypresented recently. It employs a unique impedancenetwork to couple the main circuit of the converter to thepower source. With proper control, the ZSC can buck orboost voltages to a desired magnitude, which might begreater than the available dc input voltage. The ZSC usesthe shoot-through state, turning ON two switches from thesame phase leg, to boost the input voltage. Therefore theST state now is one of the converter’s normal operatingstates and no longer a potential danger for the circuit; inaddition, there is no requirement of the dead time with theZSC, hence reliability of the system is improved [9].

The basic ZSC topology has some significantdrawbacks, namely that the input current is discontinuousin the boost mode and the Z-network capacitors mustsustain high voltage. Discontinuous input current isprohibited for many sources and requires large input filters.To a great extent this shortcoming is avoided in the quasi-Z-source converter, as shown Fig. 3-b, by the presence ofan input coil in the QZSC that buffers the source current.Moreover, voltage on one of the Z-network capacitors islower than in case of the basic ZSC topology. In addition,it is also possible to develop joint grounding of the input



power source and the dc link bus, which reduce thecommon-mode noise. Hence, the QZSC topology has nodisadvantages when compared to the traditional ZSCtopology. The QZSC topology therefore can be used in anyapplication in which the basic ZSC topology would beused [10].

(a) (b)Fig. 3 (a) The basic ZSC structure; (b) QZSC structure

Therefore, by introducing the Z-source network to theconventional matrix converter, which was recentlyproposed as Z-source direct matrix converter, as shown inFig. 4, [11], [12], [13], it is possible to overcome the lowvoltage gain of the traditional MC; in addition, the Z-source network allows the short circuit, which makes theZSDMC commutation easier. The ZSDMC is derived fromthe traditional DMC by only adding three inductors,capacitors, switches and diodes. However, the ZSDMC hasa limited voltage boost ratio (voltage gain can only reach1.15), inherited phase shift caused by the Z-network, whichmakes the control inaccurate, and also discontinuouscurrent in the front of Z-source network. However, for thequasi-Z-source direct matrix converter, as shown in Fig. 5,the voltage gain can go to 4-5 times or even higherdepending on the voltage rating of the switches, no phaseshift, which can cause less error in the control, and lowerswitch voltage and current stress [14]. In addition, thecircuit in Fig. 5-b has continuous input current [15].

Compared to traditional DMC, ZSDMC and QZSDMCboth can boost voltage higher than 0.866. The boost ratiodepends on the duty cycle of extra shoot-through state.Also the QZSDMC topology can conduct lessvoltage/current stress on the switch and passives, less inputand output harmonics and higher power factor than theZSDMC. Moreover, compared to ZSDMC topology, theQZSDMC is a component less, size compact, highefficient, wide range buck-boost matrix converter [16].

Fig. 4 Voltage fed Z-source direct matrix converter (ZSDMC) topology

(a) (b)Fig. 5 Voltage fed quasi Z-source direct matrix converter topologies

with: (a) discontinuous, (b) continuous input current

Nowadays, induction motors are widely used in industrydue to their reliability, robustness, high efficiency, andability to operate in wide torque and velocity ranges. In

order to achieve high dynamic performance in an inductionmotor drive application, vector control is often applied.Vector control makes AC drives behave like DC drives byindependently controlling the flux and the torque of the ACmotor. Therefore, the field oriented control is used in thedesign of induction motor (IM) drives in high-performanceapplications. The main idea of the field oriented control isto control of the torque and the flux separately. Indirectfield oriented control is one of the most effective vectorcontrol of induction motors due to the simplicity ofdesigning and construction [17]-[20].

In this paper the application of the QZSDMC topologyfor four-quadrant IM-ASD system is proposed. TheQZSDMC can produce the desired ac output voltage, evengreater than the input line voltage due to its boost voltagecapability. The four-quadrant speed control isimplemented using the IFOC during motoring andregenerating operation modes. The system’sconfiguration, equivalent circuit, analysis, and control arepresented in detail. Simulation and dSPACE real-timeimplementation results demonstrate the high-performanceof the proposed four-quadrants QZSDMC-IM based ASDsystem.

II. QUASI-Z-SOURCE DIRECT MATRIX CONVERTER BASEDASD

A. TopologyThe main circuit configuration of the proposed

QZSDMC-based four-quadrant IM-ASD system is shownin Fig. 6. It consists of four parts, namely, input filter,QZS-network, DMC and IM. The QZS-network includessix inductors (La1, La2, Lb1, Lb2, Lc1, Lc2), six capacitors(Ca1, Ca2, Cb1, Cb2, Cc1, Cc2), and three additionalbidirectional switches (Sa, Sb, Sc). One gate signal can beused to control these three switches because they have thesame switching state. Therefore, the drive signal for Sa, Sband Sc can be denoted as S0.

Fig. 6. Quasi-Z-source direct matrix converter based IM-ASD system

B. Operation and ModelingThe operation principle of the QZSDMC can be

divided into two switching states: shoot-through and non-shoot-through states. Fig. 7 shows the QZSDMCequivalent circuits during these states. During the STstate, Fig. 7-a, switch S0 is off and the output of theQZSDMC is shorted for boost operation. While, duringthe NST state, Fig. 7-b, switch S0 is on for normal DMCoperation. Due to the symmetry of the system, inductorsof QZS-network (La1, La2, Lb1, Lb2, Lc1, Lc2) have the sameinductance (L), and the capacitors (Ca1, Ca2, Cb1, Cb2, Cc1,Cc2) also have the same capacitance (C).



For one switching cycle, Ts, the time interval of the STstate is T0, and the time interval of the NST state is T1,hence, Ts=T0+T1, and the ST duty ratio is D=T0/Ts. FromFig. 7-a, during the ST state, one can get the followingvoltage equations:

1

1

1

1

1

1

1

1

1

1

1

1

La

Lc

Lb

Ca

Cc

Cb

Cc

Cb

Ca

Lc

Lb

La

ca

bc

ab

vvv

vvv

vvv

vvv

vvv

(1)

where v denotes the voltage, and the subscript Cx1 and Cx2are the capacitors 1 and 2 of phase-x; Lx1 and Lx2 for theinductors 1 and 2 of phase-x; x = a, b, c. During the NSTstate, its equivalent circuit is shown in Fig. 7-b, and onecan get:

1

1

1

1

1

1

1

1

1

1

1

1

La

Lc

Lb

Ca

Cc

Cb

ac

cb

ba

Cc

Cb

Ca

Lc

Lb

La

ca

bc

ab

vvv

vvv

vvv

vvv

vvv

vvv

(2)

In steady state, the average voltage of the inductors overone switching cycle should be zero, and owing to thesymmetric voltages of three-phase capacitors, one gets[12]:

ca

bc

ab

ac

cb

ba

vvv

Dvvv

211 (3)

Define B as the boost factor and it is expressed as [12]:

DvvB

i

oQZSDMC 21

1

(4)

Where vi is the amplitude of input voltage source and vo isthe output voltage amplitude of the QZS-network.However the boost factor for the ZSDMC is given by[12]:

1331

2

DDvvB

i

oZSDMC (5)

Fig. 8 shows the boost factor for both convertertopologies. Thus, the voltage gain G of the QZS-networkin the one switching cycle, is given by:

BMG (6)

(a) (b)Fig. 7. Equivalent circuit of the QZSDMC: (a) ST state; (b) NST state

Fig. 8. Boost factor of the ZSDMC and QZSDMC versus D

C. Shoot-Through Boost Control MethodThe principle of applying ST state for the QZSDMC is

to replace some of the zero state by ST state, in order tonot affect the output voltage. By using the carrier basedpulse width modulation, the zero output voltage state inMC is corresponding to the switching state that all threeoutput phases are connected to the same input phase. Ithappens when all three phase output voltages are eitherhigher or lower than the carrier signal. So the STreference should be either higher than the maximumreference voltage or lower than the minimum referencevoltage [14].

All the boost control methods that have been exploredfor the traditional ZSC, such as simple boost, maximumboost, maximum constant boost, and modified spacevector modulation [21], can be applied to the QZSDMCwith a modification of the carrier envelope. Fig. 9 shows asimple boost PWM control strategy for the QZSDMC.The carrier waveform has the same envelope with thethree-phase source voltages, va, vb and vc. The topenvelope consists of the maximum voltage among thethree input phase voltages, and the bottom envelopeconsists of the minimum voltage among them. Duringeach switching period, the modified carrier signal iscompared with the output voltage references vA, vB and vCto produce their PWM switching sequences (SA, SB, SC).The ST pulses are generated by comparing the STreferences with the modified carrier waveform, as shownin Fig. 10. The PWM switching sequences SA, SB, SCshould be distributed to nine ac switches in order togenerate the expected PWM pulses. For this purpose, sixadditional logical signals are used, as shown in Fig. 11,where Sx1, Sy1 nd Sz1 denote the indicators for theirrespective phase-a, phase-b, and phase-c of the top voltageenvelope. Sx2, Sy2 and Sz2 denote the indicators for theirrespective phase-a, phase-b, and phase-c of the bottomvoltage envelope. These six voltage envelope indicatorsare combined with the three PWM switching sequences togenerate nine switching signals according to the followinglogics:

CzCzCc

CyCyCb

CxCxCa

BzBzBc

ByByBb

BxBxBa

AzAzAc

AyAyAb

AxAxAa

SSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSSS

21

21

21

21

21

21

21

21

21

(7)

The above logical functions can be used to drive theQZSDMC after inserting the ST states.A simple boost control is achieved through two STreferences, in which both references are related to bothenvelopes by [12]:

2)( minmaxminmax

,

yynyyv rst

(8)



where n will determine the ST duty ratio, and its value hasa limitation that the resultant minimum value of the topST reference should be less than 0.5 p.u. and larger thanM. Therefore, 1≥ n ≥ (1+4M)/3 for the top ST reference,and its negative value is (-n) for the bottom ST reference.The modulation index should be less than 0.5, given thatthe output references vA, vB and vC can be any frequencywith any phase angle and with no harmonic injection. ymaxand ymin are the top and bottom envelopes of the sourcevoltages, respectively. For the simple boost control, theshoot-through interval from the top reference can becalculated as [12]:

cTnT2

10

(9)

Where T0 and Tc are the ST duration per switching cycleand switching time, respectively, and its ST duty ratio inhalf carrier cycle is [12]:

21 nDh

(10)

Fig. 9 Simple boost PWM control for the QZSDMC

Fig. 10 QZSDMC switching states generation

Fig. 12 shows the complete process to generate theswitching signals for the QZSDMC. First, the trianglecarrier signal is modulated by the input reference signalsva, vb and vc to generate the modified carrier signal whichis bounded by the maximum and minimum envelopes ofthe input reference signals. Second, the ST references aregenerated from the input reference signals and the desiredboost ratio using Eqs. 8, 9, 10. Then, the switchingsequences SA, SB, SC and ST pulses are generated bycomparing the output voltage references vA, vB and vC andthe ST references with the modified carrier signal.

Furthermore, voltage envelopes indicators are generatedfrom the input reference signals va, vb and vc. Forexample, Sx1=1 when phase-a voltage is the largest valueamong the three phase voltages and Sx2=1 when phase-ahas the minimum voltage among the three phase voltages.Finally, these six voltage envelope indicators arecombined with the three PWM switching sequences, SA,SB, SC, and the ST pulses to generate nine switchingsignals.

Fig. 11 Voltage envelopes Indicators

Fig. 12 Block diagram of QZSDMC PWM generation with ST insertion

III. INDIRECT FIELD ORIENTED CONTROL TECHNIQUE

Vector control is a technique which allows theinduction motor to act like a separate excited DC machinewith decoupled control of torque and flux, making itpossible to operate the induction motor as a high-performance four-quadrant servo drive. The idea behindvector control is that the stator current of the inductionmotor is decomposed into orthogonal components as amagnetization component (flux producing) and a torquecomponent. These components are controlledindividually. In order to obtain high dynamic performanceof the induction motor, the magnetizing currentcomponent is maintained at its rated level while the torqueshould be controlled through the torque component of thestator current. The field orientation can be generallyclassified into stator flux, air-gap flux, and rotor fluxorientations. Since the rotor flux orientations extensivelyused in ac drives, this scheme is utilized in this paper [17].The rotor flux orientation is achieved by aligning the d-axis of the synchronous reference frame with the rotorflux r vector. The resultant d- and q-axis rotor fluxcomponents are given as:

rdr

qr

0 (11)



The d-axis current dsi is referred to as flux-producingcurrent while the q-axis current qsi is the torque-producing current. In the field-oriented control dsi , isnormally kept at its rated value while qsi is controlledindependently. These steady state dq-components of thecurrent are given as:

m

rds L

i*

* (12)

*

** 2

32

rm

rqs

TLL

pi

(13)

The slip frequency, sl , is given by:

qsrr

msl iL

* (14)

The rotor flux angle e which required for coordinatetransformation, is generated from the rotor speed, r , andthe slip frequency, sl , as given by:

dtree )( (15)

The torque reference *T is generated by a PI speedcontroller based on the reference speed *

r and themeasured rotor speed r . The rotor flux reference *

r iskept constant at its rated value. The feedback dq-axisstator currents dsi and qsi are compared with theirreferences, *

dsi and *

qsi , and the errors are sent to the PI

current controllers to generate the stator voltage referencecomponents '

dsv and '

qsv , as indicated in Eq. 16, while, theremaining terms in Eq. 6 must be added to the output ofeach controller for voltage compensation [18].

compqs

v

drr

medsse

qsv

qssqssqs

compds

v

qssedr

r

m

dsv

dssdssds

LLiL

dtdi

Lirv

iLdt

dLL

dtdiLirv

'

'

(16)

The dq-axis voltages in the synchronous frame are thentransformed to the three-phase stator voltages ** ,

bsasvv and

*

csv in the stationary frame for the PWM block. Fig. 13shows the block diagram of the IFOC controlled inductionmotor. The parameters of the speed and current PIcontrollers are calculated based on Table I, where

n , are the desired damping and dynamics responsespecifications, ssm rLT , rsm LLL21 [19].

IV. PROPOSED QZSDMC BASED IM-ASD SYSTEM

The control block diagram of the induction motor drivesystem with QZSDMC is shown in Fig. 14. The speedencoder detects the rotor speed to compare it with thereference speed. The speed controller, a PI regulator, dealswith the speed error and generates the required torquereference. The IFOC block generates the modulationsignals, vabc, according to the operating conditions duringdifferent operating modes. The ST duty ratio, D, is

designed according to Eq.4, the corresponding voltagegain (G) and output voltage can be obtained to meet thedesired voltage value. The carrier based modulatorgenerates the gating signals for the DMC and theadditional switches in the QZS-network.

Fig. 13. Block diagram of the IFOC controlled induction motorTable I PI Controllers Parameters Equations

Speed controller )12(2

22

nsi

nsp

JkFJk

Current controller )12()12(

221

nmsii

nmsip

TrkTrk

Fig. 14. Block diagram of the proposed QZSDMC based IM-ASD

V. SIMULATION AND REAL-TIME IMPLEMENTATIONRESULTS

A. MATLAB Simulation ResultsIn order to verify the proposed QZSDMC-IM drive

system performance, simulations are carried out usingMATLAB/SIMULINK software for a 4 kW IM using theparameters in Table II. The QZSDMC-IM ASD systemsimulating model is tested during the motoring andregenerating operation modes, as shown in Fig. 15: theacceleration mode at no load during the time interval 0-1sec; the steady state operation mode with half the ratedload torque and the rated speed during the time interval 1-2sec; the steady state operation mode with the rated loadtorque and the rated speed during the time interval 2-3 sec;the deceleration mode from the rated speed to negative therated speed with negative the rated torque during timeinterval 3-4 sec; and the regeneration mode with the ratedload and negative the rated speed during the time interval



4-5 sec. Fig. 15 shows the system ability to perfectly trackthe speed and load torque references during differentoperation modes. Also, Fig. 16 shows the motor responseduring speed reverse, where, the motor speed tracks itsreference and the motor current and voltage waveforms arereversed. Fig. 17 shows the steady state motor responseduring motoring operation at rated conditions.The given ST duty ratio D is 0.1. According to (4) and (6),one can get the boost factor B of 1.25 and the maximumvalue of voltage gain G is 1.125. Fig. 18 shows the outputline voltage amplitude (around 670 V) of QZS-network,which is 1.25 times of input line voltage amplitude.

Fig. 15 Motor response during motoring and regenerating operationmodes

Fig. 16 Motor response during speed reverse

Fig. 17 Steady state motor current and voltage waveforms duringmotoring at rated conditions

Fig. 18 Input and output line-to-line voltage of the QZS-network

Fig. 19 Input and output current of the QZS-network

(a)

(b)Fig. 20 (a) QZSDMC input current THD, (b) motor current THD

Table II Simulation System ParametersParameter ValueQZSDMC parameters:QZS-network inductance, L 100 µHQZS-network capacitance, C 10 µFQZSDMC Switching frequency, Fs 10 kHzInput voltage source parameters:AC input line-to-line RMS voltage 380 VAC input voltage frequency 50 HzInduction Motor parameters:Output power 4 kWRMS line voltage 400 VMotor frequency 50 HzNo. of poles, p 4Stator resistance, Rs 1.405 ΩRotor resistance, Rr 1.395 ΩStator inductance, Lls 5.839 mHRotor inductance, Llr 5.839 mHMutual inductance, Lm 172.2 mHInertia, J 0.0131 kg. m2Friction coefficient, J 0.002985 N.m.s



B. Real-time Implementation ResultsThe real-time system, as shown in Fig. 21, contains a

DS1103 PowerPC Processor board, including onboard I/Ofor Analog to Digital converters, Digital to Analogconverters, Digital I/O, and a RS232 serial interface. Alsoincluded in the system is a bus interface board to connectthe real-time system to the PC. For modeling and codegeneration MATLAB, Simulink, Real Time Workshop(RTW) by The MathWorks and the Real Time Interface(RTI) by dSPACE are installed. ControlDesk softwarefrom dSPACE is used for as a front-end and serves toprovide instrumentation, parameterization, measurementsand experiment control. Fig. 22 shows the motor real-timeresponse during speed reverse with rated load torque andFig. 23 shows the real-time motor steady-state responseduring motoring operations with rated conditions. Fig. 24shows the real-time waveforms of the input and outputline-to-line voltage of the QZS-network, where therequired voltage gain is achieved by inserting the ST state.There is a good matching between MATLAB simulationand dSPACE real-time implementation results.

Fig. 21 dSPACE real-time implementation block diagram

Fig. 22 Real-time motor response during speed reverse with rated loadtorque

Fig. 23 Real-time motor steady state line voltage and phase currentwaveforms during motoring operation under rated conditions

Fig. 24 Real-time waveforms of the Input and output line-to-line voltageof the QZS-network

VI. CONCLUSION

This paper proposed a new four-quadrant vectorcontrolled induction motor adjustable speed drive systembased on the QZSDMC topology. The proposed systemovercomes the reduced voltage transfer ratio limitations oftraditional DMC-based ASD system, therefore, theproposed QZSDMC-IM based ASD will increase theapplication of the DMC in different industry fields. Theproposed ASD system can operate at full load with smallQZS-network elements. The QZSDMC can achieve buckand boost operation with reduced number of switchesneeded, therefore achieving low cost, high efficiency, andreliability, compared to the traditional DMCs, in addition,there is no requirement of dead time with QZS-network,hence commutation of the QZSDMC is easier than thetraditional DMC. The proposed ASD system can providea voltage gain larger than one and can operate in motoringand regenerating operation modes with perfect referencestracking as verified by MATLAB simulation and dSPACEreal-time implementation results.

ACKNOWLEDGEMENT

This publication was made possible by by the NPRPaward [NPRP-EP No. X-033-2-007] from the QatarNational Research Fund (a member of Qatar Foundation).The statements made herein are solely the responsibility ofthe authors.

REFERENCES

[1] J.D. van Wyk and F.C. Lee, “On a Future for Power Electronics”,IEEE Journal of Emerging and Selected Topics in PowerElectronics, vol.1, no.2, pp. 59-72, June 2013.

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[6] M. Jussila and H. Tuusa “Comparison of Direct and Indirect MatrixConverters in Induction Motor Drive”, 32nd Annual Conference onIEEE Industrial Electronics, IECON 2006, pp.1621,1626, 6-10Nov. 2006.

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[8] Paweł Szcześniak, "Three-phase AC-AC Power Converters Basedon Matrix Converter Topology, Matrix-reactance frequencyconverters concept", Springer-Verlag London 2013, ISBN: 978-1-4471-4895-1.

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[13] Shuo Liu, Baoming Ge, Haitham Abu-Rub, Fang Zheng Peng andYushan Liu, “Quasi-Z-Source Matrix Converter Based InductionMotor Drives”, the 38th Annual Conference of the IEEE IndustrialElectronics Society, IECON 2012, Canada, 25-28 October 2012.

[14] Qin Lei, Fang. Z. Peng and Baoming Ge, “Pulse-Width-Amplitude-Modulated Voltage-Fed Quasi-Z-Source Direct Matrix Converterwith maximum constant boost” the twenty-Seventh Annual IEEEApplied Power Electronics Conference and Exposition (APEC), 5-9Feb. 2012.

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[19] Ned Mohan , “Advanced Electric Drives: Analysis, Control, andModeling Using Simulink”, MNPERE, 2001

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[21] Omar Ellabban, Joeri Van Mierlo and Philippe Lataire,“Experimental study of the shoot-through boost control methods forthe Z-source inverter”, EPE Journal, Vol. 21, No. 2, pp. 18–29, Jun.2011.

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Omar Ellabban (S’10–M’12–SM’13) was born inEgypt in 1975. He received the BSc with honors fromHelwan University, Egypt in 1998 and the MScdegree from Cairo University, Egypt in 2005, both inElectric Power and Machines Engineering, and thePh.D. degree with the greatest distinction in ElectricalEngineering from Vrije Universiteit Brussel, Belgium

in May 2011. In May 2011, he joined the R&D Department, PunchPowertrain, Sint-Truiden, Belgium, where he and his team developed anext generation, high- performing hybrid powertrain. Since May 2012,he has been an Assistant Professor in the Department of ElectricalMachines and Power Engineering, Helwan University. In June 2012, hejoined Texas A&M University at Qatar as Postdoctoral Research

Associate and then as Assistant Research Scientist in December 2013,where he is involved in different renewable energy projects. Dr. Ellabbanhas published more than 35 journal and conference papers and one bookchapter and one conference tutorial. He is an active IEEE senior memberand he act as a reviewer for different IEEE journals and conferences. Inaddition, he has been listed in Marquis Who's Who in the World (2014,31st Edition). His research interests include automatic control, motordrives, power electronics, electric vehicles, switched reluctance motor,renewable energy and smart grid.

Haitham Abu-Rub (M’99–SM’07) holds two PhDs,one in electrical engineering and another inhumanities. Currently he is a professor with TexasA&M University at Qatar. His main research interestsare energy conversion systems, including renewableand electromechanical systems. His work relates tothe high performance electric drives, renewable

energy systems, multilevel inverters, impedance source inverters andtheir modifications, pulse width modulation techniques, model predictivecontrol, and other related topics. Dr. Abu-Rub is the recipient of manyprestigious international awards, such as the American FulbrightScholarship, the German Alexander von Humboldt Fellowship, theGerman DAAD Scholarship, and the British Royal Society Scholarship.Dr. Abu-Rub has published more than 200 journal and conference papersand is leading many potential projects in electric drives, photovoltaic andhybrid renewable power generation systems with different types ofpower electronics converters. He is co-author of four books, three ofwhich are with Wiley (one of them in process). He is also an author andco-author of few book chapters. Dr. Abu-Rub is an active IEEE seniormember and is an editor of the IEEE Transactions on Sustainable Energyand the IEEE Journal of Emerging and Selected Topics in PowerElectronics.

Baoming Ge (M'11) received the Ph.D. Degree inelectrical engineering from Zhejiang University,Hangzhou, China, in 2000. He was a PostdoctoralResearcher in the Department of ElectricalEngineering, Tsinghua University, Beijing, China,from 2000 to 2002, was a Visiting Scholar in theDepartment of Electrical and Computer Engineering,

University of Coimbra, Coimbra, Portugal, from 2004 to 2005, and was aVisiting Professor in the Department of Electrical and ComputerEngineering (ECE), Michigan State University (MSU), East Lansing,Michigan, from 2007 to 2008, and currently he is working with the ECEof MSU; he also is a Professor with the School of Electrical Engineering,Beijing Jiaotong University, Beijing, where he has joined since 2002.His research interests include renewable energy power generation,electrical machines and control, power electronics systems, and controltheories and applications.

Documents

A Quasi-Z-Source Direct Matrix Converter Feeding a Vector Controlled Induction Motor Drive