Research Paper on Mobile Charging

7/27/2019 Research Paper on Mobile Charging

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Ayushi Vaishy, et al International Journal of Research in Electronics & Communication Engineering [Volume 1, Issue 1, April 2013]

Webpage:http://ijrece.org Page 5

Abstract -People who are livi ng off grid can now charge their mobile

phone just by sending an message by their mobil e phone. It i s possibl e

by the solar powered cell phone charging station. Th is charging

station is start wor king when it receives a message of char ging the

mobile by the user. This technology is very useful for the ru ral areas

of developi ng countr ies where the supply of electri city is uncertain . It

is the cheapest method found so far to charge mobile for ru ral areas.

Rur al ar eas need stronger signals fr om cell phones because there are

few number of tower nearby. I n th is techni que battery is charged by

the solar panel. The battery extr act the power to char ge fr om the solar

power charging station by a techni que called Maximum Power Poin t

Tracking (M PPT). Power output of solar panel depends on the

environmental conditions like temperature, sunlight and the

resistance of the cir cui t connected to it MPPT changes the resistance

and moni tors the conditi ons to get maximum possibl e power output

with in given time. Device importan t part is the way stored power i s

used to charge the phone. When a customer sends a text message to

the device on receiving th e message an LED above the socket of thebattery starts li ghtn ing it i ndi cates that the stored power i s ready to

charge the phone.

Keywords - Solar powered cell phone charging station, MPPT, SMS

Techni que, Photo-voltaic Cell , I nduction Procedure.

I. INTRODUCTIONTOMAXIMUMPOWERPOINTTRACKING(MPPT)TECHNIQUE

To maximize the output power it is necessary to continuously

track the maximum power point of the system. MPPT stands for

maximum power point tracking or tracker. MPPT are used withsolar energy panels. When under given circumtances the solar

energy panel are riches at its maximum electrical threshold level

than it is known as maximum power point. The maximum power

point will be decided by the sunnier day or cloudier day. Due to

the uncertainty of sun light the maximum power point also will

not be fixed. Because of the fluctuation in level of sun energy the

capacity of solar energy panel will also be reduce.

Large amount of power fed to the system will not be able to

handled by the battery voltage in this way one can be unable to

receive proper amount of power. If we transmit the data

wirelessly than it will consume large amount of output power. Insolar panels we use limited amount of power supply. On

operating solar panels maximum power point and by intelligently

using the amount of power from the panels energy can be

consumed usefully

When there is no sunlight and solar panel is not producing

energy and providing to the cell phones then the electricity in the

battery will flow in backward direction through the solar energy

panel. MPPT in this situation disconnect the circuit to stop the

reverse flow. Solar panels have relation between radiation

temperature and resistance by which an output efficiency

produced which will be analysed by an I-V curve. By the proper

resistance maximum power can be obtained in the certaincircumstance which is the main purpose of MPPT technology.

Fig.1: Graph of solar panels MPP

In MPPT technology we basically work with power and

voltage. The maximum power point of a solar panel can be

tracked. When solar panel is at its maximum power MPPT tracts

that moment and also adjust the power accordingly to provide

An Effective and High Performance Approach

of Charging the Mobile Phones by using SMSwith MPPT Technology

Ms.Ayushi Vaishy1, Dr.Ajita Pathak

2, Mr.Rajinder Tiwari

3

Department of Electronics & Electrical Engineering,

Amity University Uttar Pradesh, [email protected],2 [email protected],[email protected]
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stability to the battery and increases electrical power production.

MPPT stops battery from over charging and from system short

circuiting. MPPT gernaly have digital display screen to view

various readings. Solar panel provides peak output power when

works at MPP. We can gernalize MPP as voltage and current

corresponds to maximum output power obtained by the solar

panel. The voltage of solar panel decreases as current drawn from

the panel increases it is a characterstic of solar panels MPP

technology. If the current drawn is very high than in this satuation

voltage will be collapse and the power drawn from the panel willbecome too small. In fig output curren an output power versus

output voltage graph of a particular solar panel has been taken.

MPP is shown in between point 1 and point 2 on the power line.

A horizontal line shows the in the graph is the output power is

90% of the MPP. The panels maximum power is between point 1

and point 2.

There are many algorithms are used to calculate MPPT.

Algorithm used in MPPT is based on to detect the maxima of the

power. Radiance level at differ points of solar panel varied

dependent on the temperature variation by which there are

multiple local maxima in one system are generated. If a true

maximum power point and local maximum power point iscalculated than the efficiency and complexity of an algorithm can

be defined easily and maximum electrical power will not be

extracted from the panel. Perturb and Observe alogorithm is most

commonly used in MPPT because of it is easy to implement on

comparison of other algorithms. The aim behind this algorithm is

to modify the voltage and current till the maximum power output

get from the solar panel. If increasing in voltage increases the

power output than voltage will be extent till the extant until the

power will start decreasing. After this the voltage decreased to

get bact the maximum power output. This satuation will go on

until the satuation of maximum power point is obtained.

Fig: 2: Flow chart of Perturb and Observe Tracking system

It refered as hill climbing method because it depends on the

rise of the curve of power against voltage below the maximum

power point and the fall above that point. Petturb and Observe

algorithm provides very high level of efficiency in MPPT.

II. MAXIMUMPOWERPOINTTRACKINGPHOTO-VOLTICSYSTEM

Photovoltic system is using as source of power for many

application so far. It converts light energy to electrical energy

with greater efficiency and lowest cost and to maximize the

output power. PV system that lack MPPT is unable to operate at

the efficient MPP. So the rated power of solar panel is difficult to

analize when it is connected to the load. The Perturb and Observe

(P& O) technique can be use to overcome with this problem o

MPPT. According to this if the operating voltage of the PV

system is Perturb in the given direction and if the power in the

system is incrsing constantly than in this satuation the operating

point will move towards the MPP so operating voltage must be

further Perturb in the same direction and if the power drawn from

the PV system decreses than the operating point will move away

from the MPP and the direction of the operating voltage will be

riversed. By adding P& O algorithm in the system it adds

flexibility and find where the system can be easily constructed

Some components needed to use to overcome the problem occur

in MPP when solar panel is connected to the load as solar panel,

DC-DC converter, Digital controller, current sensor , voltage

sensor and logic circuitry for connection.

Fig: 3: MPPT for PV system

DC-DC Converter: DC-DC converter which is a electronic

circuit is used to convert direct current to one voltage level to

another. This converters stores the input energy temporary and

release the energy at the output at different current and voltage

level. It is basically used as power converter and no energy is

manufactured itself in the converter. It changes the energy at

different impedance level and the output power is totally

dependent on the input power.In this convertr a electrical load is

connected to the solar panel which varies according to the output

voltage of the panel. This changes is load changes the voltage and

current characterstics so by controlling the converters

characterstics the power can be controlled and obtain maximum

power for the panel. This technique make DC-DC converter very

essential for the MPPT. The MPPT Controler- Microcontroler

provides control in the PV system. Controler used must be cos

effective, good performance and must be flexible for the entire

system. Controler must provide real time control applications

which improve system efficiency, reliable and flexible when

complex algorithms are used.
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Fig 4: MPPT Circuit for a Pulsed Load

There are few single-device, cost-effective solutions that

operate from the wide voltage range of power-limited solar-panel

inputs while efficiently providing a regulated output voltage, a

quick start-up, and operation within 90% of the MPP. However,

the Texas Instruments TPS62125 is one such device that accepts

input voltages of up to 17 V, operates with efficiencies in excess

of 90%, starts up in less than 1 ms, and has an enable input pin

with a precise thresh-old that can be directly wired to the solarpanels voltage for MPPT.

This eliminates the need for an additional device to per-form

this function. Figure 2 shows a complete solution. The voltage

divider, formed by R1 and R2, is configured to turn on the power

supply at Point 1 in Figure 1. Until the power supply is enabled,

the device itself holds the node between R2 and R3 at ground

potential. After the supply is enabled, the device releases this

node, and R3 is then part of the voltage divider. When the solar-

panel voltage falls to Point 2, the device turns off and holds the

node low between R2 and R3 again. At this point, the panel

voltage begins to rise again until it reaches the turn-on threshold.

This provides a fully programmable turn-on and turn-off voltagethat can be configured to any solar panel.

The bulk input capacitor, C3, stores enough energy from the

solar panel to power the load for the required duration and

provides the charge for starting up the power supply. The panel

delivers a current corresponding to its voltage to either the power

supply or C3. When the power supply is off, the solar panel

delivers its current to the capacitor. When the power supply is on,

the capacitor and solar panel provide the necessary current to

power the load. Since C3 merely stores energy and this energy is

released over a relatively lengthy period of time, C3 can be a

low-cost electrolytic capacitor.

The first step in designing the MPPT circuit is determining the

loads power needs and then computing the amount of required

bulk input capacitance based on these power requirements and

the chosen solar panel. As an example, assume a remote sensing

circuit requires 3.3 V at 250 mA (825 mW) for a duration of 15

ms. These are typical needs for a system that contains a

measurement device, a micro-processor, and an RF transmitter.

After the loads power needs are determined, the required value

for C3 is calculated. First, the input current required to power the

load is found from Equation 1:

IN

IN

OutputPowerI

V

(1)

VIN is the average solar-panel voltage between Points 1 and 2

in Figure 1, and is the power-supply efficiency at the given

output power. Notice that the typical efficiency of the power

supply at a VIN of about 7.8 V and an output power of 825 mW

is around 87%. Using these numbers, IIN = 122 mA. This is

much greater than what Figure 1 shows the solar panel to becapable of providing, so C3 must store enough energy to provide

the remaining current for 15 ms. Equation 2 determines the

required C3 value based on the load requirements and solar-pane

characteristics:

1 2

3IN ONPanel Avg

P P

I I tC

V V

(2)

VP1 and VP2 are the voltages at Points 1 and 2, which are

respectively about 9 V and 6.5 V for this panel, and correspond

to the voltage change across C3 as it discharges. The requiredload operating time, given by tON, is 15 ms. Finally, IPanel(Avg)

is the average current from the solar panel when the panel is

operated within 90% of its MPP. As seen in Figure 1, this current

is about 19 mA. From Equation 2, it is determined that C3 should

be greater than 618 F. A 680-F capacitor is used to provide

some margin in the operating time.

R1, R2, and R3 form a fully configurable voltage divider with

hysteresis for the enable (EN) pin. Equations 3 and 4 are used to

set the resistor values:

1

1

2

1.20 1P

R

V V R

(3)

1

2

2 3

1.15 1P

RV V

R R

(4)

R1 is chosen first, and 1 M is a good starting value. With this,

R2 is calculated to be 153.8 k. The closest standard value of

154 k is chosen. R3 should be 60.9 k, and

60.4 k is the nearest standard value.

Voltage Sensor-

To measure the voltage which is provided by the solar paneltwo resistorsR1 and R2 act as as voltage devider when employed

in parallel with the solar panel. The voltage across R2 is fed in to

a ADC converter and in the voltage follower configuration that is

fed to the low pass filter before fedding to the ADCINA0 which

is a channel of MPPT controller. If we take R1 1.07 M and R2

165 k respectively than the maximum amount of current from

the load is 12. The voltage range is 0-3 Vdc for MPPT controller.


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Fig. 5: Sensing circuit of voltage sensor

Fig: 6: Sensing circuit of Current Sensor

To measure current which is provided by the solar panel a

resistor is placed in between solar panel and DC-DC converter in

series. Current sensors are made by analog devices by which

output voltage is fed to the ADC. The voltage across resistor is

fed to the ADCINA1. OP-AMP is in voltage followerconfiguration that pass through a low pass filter before feding to

ADCINA1 channel of of MPPT controler. By choosing the value

of resistor 51 m maximum voltage drop across the resistor

occurs. The voltage range of ADC channel of MPPT controller

0-3 Vdc so the output voltage of AD8215 current sensor which

is voltage representation of solar panels current should not

exceed to 3 Vdc.

III. SIMULATIONRESULTS&ANALYSISFigure 3 shows the MPPT circuit in operation. The panel

voltage, VIN, remains between 9 V and 6.5 V (VP1 and VP2,

respectively). Once VOUT enters regulation, the load enables

and draws 250 mA. When the panels voltage drops to 6.5 V,

VOUT is disabled and thereby disables the load current. The

solar panel provides an average of 19 mA at all times. The load

has a run time of around 18 ms in Figure 3, meeting the 15-ms

requirement. This run time roughly matches the calculations,

since the value of C3 increased above the result of those

calculations. Figure 4 replaces the output-voltage trace in Figure

3 with the trace for ICap, the current from C3. As VIN decreases,

the current leaving the capacitor is positivethe capacitor

provides its stored energy to the power supply, which then

supplies that energy to the load. Once the load turns off, due to

the panel voltage decreasing to 6.5 V and the power supply

disabling, the current from C3 goes negativethe capacitor

recharges from the panel and stores energy for the next cycle

The current from C3 spikes briefly before the load is enabled, as

the power supply turns on when the panel voltage is sufficiently

high. Additional input current provided by C3 is needed during

start-up.

Fig: 7: Operation of MPPT circuit within 90% of MPP

Fig: 8: Bulk input capacitor (C3) supplying a circuit operating

within 90% of MPP

Fig: 9: RS vs Reciprocal of Irradiance


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Fig: 10: Angle of Incidence vs Relative Output Current

Fig: 11: VOC vs ln(irradiance)

Fig: 12: VMP vs Illumination (Lux) for Low Irradiance

Fig: 13: PV Output Power at 1000W/m2 and 400W/m2

vs PV Voltage and Current

IV. CONCLUSIONSWhen the battery in the off grid system are fully charged and

the PV production exceeds to the local load so the excess power

has no load to absorb it and MPPT no more operate at its

maximumum power point. So MPPT must shift its operating

point till production does not matches the demand. A wel

engineered renewable remote energy system, utilizing the

principal of Maximum Power Point Tracking (MPPT) can

improve cost effectiveness, has a higher reliability and can

improve the quality of life in remote areas. A high-efficient

power electronic converter, for converting the output voltage of a

solar panel, or wind generator, to the required DC battery bus

voltage has been realized.

The converter is controlled to track the maximum power point

of the input source under varying input and output parameters

Maximum power point tracking for relative small systems is

achieved by maximization of the output current in a battery

charging regulator, using an optimized hill-climbing, inexpensive

microprocessor based algorithm. Through practical field

measurements it is shown that a minimum input source saving of

between 15 to 25% on 35 kWh/day systems are easily be

achieved. A total cost saving of at least 1015% on the capita

cost of these systems are achieveable for relative small rating

Remote Area Power Supply (RAPS) systems. The advantages a

large temperature variations and high power rated systems are

much higher. Other advantages include optimal sizing and system

monitor and control.

ACKNOWLEDGEMENT

The authors are thankful to Mr. Aseem Chauhan (Additiona

President, RBEF and Chancellor AUR, Jaipur), Maj. General K

K. Ohri (AVSM, Retd.) Pro-VC, Amity University, Lucknow

Prof. S. T. H. Abidi (Director ASET, Lucknow Campus), Brig

U. K. Chopra (Director AIIT & Dy. Director ASET), Prof O. PSingh (HOD, Electrical & Electronics) and Prof. N. Ram (Dy

Director ASET) for their motivation, kind cooperation, and

suggestions.

REFERENCES

[1] G Hsiao Y.T. e C.H. Chen C.H., Maximum Power Tracking

for Photovoltaic Power System in Proceedings of IEEE

Industry Applications Conference - 37th IAS Annua

Meeting, 2002.

[2] Sera D., Kerekes T., Teodorescu R., Blaabjerg F., Improved

MPPT Algorithms for Rapidly Changing Environmenta

Conditions in the Proceedings of Power Electronics and

Motion Control Conference, EPEPEMC 06, 2006.[3] T. Noguchi, S. Togashi, R. Nakamoto, Short-Current Pulse

Based Maximum Power Point Tracking Method for Multiple

Photovoltaic and Converter Module System, IEEE Trans

Industrial Electronics, 2002.

[4] Ortiz R. E. I., A MPPT Method based on the

Approximation of a PVM Model using Fractiona

Polynomials in Proceedings of IEEE Power Electronics

Specialists Conference, PESC2007.

[5] D. Casadei; G. Grande e C. Rossi.: Single-Phase Single

Stage based Photovoltaic Generation System Based on a


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Ripple Correlation Control Maximum Power Point

Tracking, IEEE Trans. Energy Conversion, 2006.

[6] Markvart T.: Solar Electricity, John Wiley & Sons, 1994.

[7] Lorenzo E., Araujo G.L., Cuevas A., Egidio M.A., MianoJ.C., Ziles R.: Eletricidad Solar Ingenieria De Los Sistemas

Fotovoltaicos; PROGENSA, 1 edicin, 1994.

[8] CRESESBE/CEPEL: Energia solar Princpios eAplicaes. Centro de Referncia para Energia Solar e

Elica Sergio de Salvo Brito: Sistema Eletrobrs, Brasil,

2000.[9] ALTENER/GREENPRO: Energia Fotovoltaica:Manual

sobre tecnologias projeto e instalao; Unio Europia,

2004.

[10]C. Cabal; C. Alonso; A. Cid-Pastor; B. Estibals; L. Seguier,

R. Leyva, G. Schweitz, J. Alzieu.: Adaptive digital MPPT

control for photovoltaic applications in Proceedings of

IEEE International Symposium on Industrial Electronic,

2007.

[11]Energy comparison of MPPT techniques for PV Systems,

ROBERTO FARANDA, SONIA LEVA

[12]ADVANCED ALGORITHM FOR MPPT CONTROL OF

PHOTOVOLTAIC SYSTEMS, C. Liu, B. Wu and R.

Cheung[13]On the control of photovoltaic maximum power point tracker

via output parameters, D. Shmilovitz

[14]An investigation of new control method for MPPT in PVarray using DC DC buck boost converter, Dimosthenis

Peftitsis, Georgios Adamidis and Anastasios Balouktsis

AUTHORS BIBLIOGRAPHY

Dr. Ajita Pathak PhD (Lucknow University), M.Sc (

Electronics) from Jivaji University Gwalior is a member of

academic staff of Department of Electronics & Electrical

Engineering (ASET), Amity University Uttar Pradesh, Lucknow,

where she is serving in the capacity of Asstt. Professor in theDepartment of Electronics Engineering (ASET).

Mr. Rajinder Tiwari,PhD (P), M.Tech,MIETE

is a member of academic staff of Department of

Electronics & Electrical Engineering (ASET),

Amity University Uttar Pradesh, Lucknow,

where he is serving in the capacity of Asstt.

Professor in the Department of Electronics

Engineering (ASET). He has done M.Tech

(I&CE) and M.Sc (Electronics) from NIT, Kurukshetra and

University of Jammu, respectively. Presently, he is pursuing

Ph.D. (ECE) from Department of Electronics Engineering,

Kumaon Engineering College, Dawarahat (Almora) underUttarakhand Technical University. Mr. Tiwari has given his

contribution to the area of Microelectronics (Modeling &

Simulation of the Analog CMOS Circuits for ASP Applications),

Embedded System Design, Digital System Design and Process

Industries Automation and Control System Design (using

Graphical Programming Language with dedicated Hardware). He

has published several research papers in International/National

Journals/Seminar/Conference. He is associated with several

technical institutions and bodies as a life member. Before taking

the assignment of Amity University, Uttar Pradesh, Lucknow, he

had worked in Electronics for Societal Group, CEERI, Pilani, as

a Project Scientist and a Multi National Company as a Sr

Software Engineer (Bridge Instrumentation Division). He is also

associated with the successfully implementation of the Hardware

and Software for number of projects undertaken by him and in

organizing number of International/National Conferences and

Seminars.

Ms. Ayushi Vaishy, M.Tech (P) from Amity University Uttar

Pradesh, Lucknow in Electronics andCommunication Engineering and did B.Tech

from Saroj Institute of Technology and

Management, Lucknow in Electronics and

Communicationn engineering in the year

2010. Her area of intrest in research field is

Wireless Communication. She has published

research paper by the name An Innovative

Solution to Empower the WiMAX Grid Network for Smart

Applications: An Innovation in Intelligent Networks Approach

in a international journal.. Presentely working on project wireless

communications with MATLAB and Simulink : IEEE.802.16

(WiMax) Physical layer as the part of her M.Tech fina

dissertation.

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Research Paper on Mobile Charging