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Final Year Project Presentation. Solar Powered Battery Charging System Catherine Conaghan. Objective. To develop a small scale solar powered system that will power a DC load, which incorporates power management techniques, DC-DC conversion and a user interface. Solar Power. - PowerPoint PPT Presentation

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Page 1: Final Year Project Presentation
Page 2: Final Year Project Presentation

To develop a small scale solar powered

system that will power a DC load,

which incorporates power management

techniques, DC-DC conversion and a

user interface.

Page 3: Final Year Project Presentation

Renewable energy source Non-polluting Reliable Can work anywhere sun is shining No major mechanical parts Relatively no maintenance Noise Free Last decades

Page 4: Final Year Project Presentation

SolarPanel

DC-DC ConverterLoad

Controller Back-upBattery

Page 5: Final Year Project Presentation

Silicon cells combined in series or parallel Converts solar energy into electricity Cell Technologies

› Copper Indium Selenide (CIS) and Amorphous› Monocrystalline and Polycrystalline

Current varies with cell size and light intensity

Page 6: Final Year Project Presentation

Rp

Rs

Iph D

pdph IIII

p

soNsTKn

RsIVq

satph R

RIVeIII cell

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.

)](1.[. refcellIscref

screfph TTS

SII

IdVo

Ip

Page 7: Final Year Project Presentation

Peak Power of 10 Watts

Vmpp = 15.6 V Impp = 0.64 A

Shell ST10

Voc = 22.9 V Isc = 0.77 A

The solar panel was tested withdifferent resistances under aconstant light source

+

-V

Page 8: Final Year Project Presentation
Page 9: Final Year Project Presentation
Page 10: Final Year Project Presentation

Two MPPT algorithms were considered: Incremental Conductance Method

› By comparing incremental conductance with instantaneous conductance.

Perturb & Observe Method› By periodically perturbing the PV array

voltage and comparing the output power with that of the previous cycle. The operating point oscillates around the MPP since the system is continuously perturbed.

Page 11: Final Year Project Presentation

Algorithm was implemented using LabVIEW

Solar panel read via a NI-USB 6009

The voltage was measured across a high power resistor to read current

Duty cycle output on NI USB 6009 digital output line

Start

Set Duty Out

Read V, I

P_new = V*I

P_new > P_old Duty = Duty(-)

Duty = Duty(+)

P_old P_new

Page 12: Final Year Project Presentation

Used to implement P&O algorithm› ‘G’ programming

Also used to generate a user interface through the front panel› Waveforms showing voltage and current of

solar panel› Numeric indicator showing power› Duty cycle displayed› ‘Stop’ button to end program

Page 13: Final Year Project Presentation

Data acquisition tool

Read data in, and generate digital signals out

Does not have a hardware counter, cannot generate digital outputs at high frequencies

Solution M series

Page 14: Final Year Project Presentation

DC-DC converter needed for two reasons› To implement the MPPT algorithm› To bring the DC voltage to an acceptable

level to power the load

Buck converter was chosen and designed

Page 15: Final Year Project Presentation

The most important components are the inductor and capacitor

Use Vo = DVi to deduce ideal duty cycle range (0.3 – 0.5)

Using both of these values for D, and the ΔI equation two values for the inductor were calculated (2.8 mH & 1.6 mH)

Using the ΔV equation the capacitor value was determined (21.3 μF)

Page 16: Final Year Project Presentation

Vin

2.2 mH

22 uF

LOAD

+

-

+

-

D

PWM

Page 17: Final Year Project Presentation

Solar panels only generate power when there sun available

Storage element is recommended Various rechargeable battery cell

chemistries› Lead Acid› Nickel-Cadmium› Nickel-Metal-Hydride› Lithium Ion

Page 18: Final Year Project Presentation

Up to 99% efficiencies Highest weight to energy ratio Average voltage of one Li-ion cell is

3.6-3.7 Volts A Li-ion battery pack with a capacity of

4 AH would be enough to store all energy generated on the longest day of the year at maximum power

Safety issues

Page 19: Final Year Project Presentation

Overvoltage Over discharging can

cause short circuit Battery packs usually

include protective circuit› Limits input voltage› Limits discharge

voltage Li-ion charger IC is

recommended to implement charging profile

Page 20: Final Year Project Presentation

Initially it was thought a mobile phone charging algorithm would have to implemented

Research showed that the charging algorithm is employed on the phone

To prove this, a commercial Nokia car cigarette lighter charger was disassembled

A ‘ma34063a’ DC-DC converter was found To charge a mobile an appropriate

constant voltage is needed, along with some circuitry protection

Page 21: Final Year Project Presentation

Solar cell equivalent circuit, characteristics and various cell technologies

Maximum power point tracking techniques LabVIEW – ‘G’ programming and user

interface DC-DC converter design including choosing

appropriate components and simulation in Pspice

Rechargeable Batteries