Battery pack designs for Electric Vehicles (EVs) are complex and vary widely by manufacturer and specific application.Battery packs for all electric drive EVs can contain several hundred individual cells.The large stack of cells is typically grouped into smaller stacks called modules.Batteries in EVs must be periodically recharged.BEVs most commonly charge from the power grid (at home or using a street or shop recharging point), which is in turn generated from a variety of domestic resources, such as coal, hydroelectricity, nuclear and others.
10 cells is connected in series.Charging balancing module is used to make sure that all 10 cells have same capacity during charging.Charging module is used to charge the cells.
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Block diagram of control unit
1. Design of Charging Module and Charging Balancing Module for Electric VehicleBy:Muhammad Suhaimi Bin Adanan Battery PackSupervisor:Mohd Rezal Mohamed
2. INTRODUCTION• Any electric car that uses batteries needs a charging system to recharge the batteries. The charging system has two goals: – To pump electricity into the batteries as quickly as the batteries will allow – To monitor the batteries and avoid damaging them during the charging process
3. OBJECTIVES• To design a charging module and charging balancing module for EV battery pack.• To ensure that all cells capacity are balance during charging.• To avoid overcharge during battery charging.
4. PROJECT SCOPE• This project will analyse the charging module and charging balancing module for electric powered Proton Saga BLM.• Battery type: Lithium Iron Phospate (LiFePO4)• 96V 100Ah
5. PROBLEM STATEMENT• If the charging process is done without charge balancing, the batteries are not at the same SOC.• In this case, the batteries with less restored energy will be exhausted first when the battery bank is reused.• For this reason, charge balancing should be included in the charging control of series- connected batteries.
6. PARAMETERS• Parameters that will be analysed are: o Voltage o Current o State of Charge (SOC)
7. SOC MEASUREMENT The state of charge (SOC) is the present capacity of the battery. It is the capacity that remains after Current Sensor discharge from a top-of-charge Load condition. i(t) dq+ - i (t ) dt dSoCT dq Battery Qt i(t )dt t SoCT (t ) QT i( )d 0
10. THE PROS AND CONS OF EACH CHARGING METHODMethod Advantages DisadvantagesConstant current method Has ability of limited current It is easy to overcharge in to prevent the over current later stage of initial chargeConstant voltage method Has ability of limited voltage Easy to over current in initial to prevent the over voltage stageConstant current / constant Can limit voltage and current Charge time is too longvoltage methodPulse charge method Can reduce the polarization Control is complex to prevent the battery temperature riseReflexTM charge method Can reduce the polarization Control is complex to prevent the battery temperature rise
13. Balancing Methods Balancing Major Components Needed Best Modular Nature to Balance an n Cell String Effective Design Period CapabilityDissipative Shunt Resistor Shunting n Switches, n Resistors Recharging Easy Analog Shunting Shunting n Transistors Recharging Very EasyPWM Controlled Shunting Shunting 2(n-1) Switches, n-1 Recharging Moderate Inductors Boost Shunting Shunting n Switches, n Inductors Recharging Moderate Complete Shunting Shunting 2n Switches, n Diodes Recharging Moderate Switched Capacitor Shuttling 2n Switches, n-1 Capacitors Recharging & Easy DischargingSingle Switched Capacitor Shuttling 2n Switches, 1 Capacitor Recharging & Poor Discharging Step-Up Converter Energy Converter n Isolated Boost Converter Recharging Easy Multi –winding Energy Converter I n Winding Transformer Recharging Very Poor transformer Ramp Converter Energy Converter 1 n/2 Winding Transformer Recharging Very Poor Multiple Transformer Energy Converter n Transformer Recharging Easy Switched Transformer Energy Converter n+3 Switches 1 Transformer Recharging Moderate Resonant Capacitor Energy Converter 2(n-1) Switches, 2n Inductors Recharging Easy
14. CHARGE EQUALIZATION CIRCUIT
15. Voltage B1 Sense Voltage B2Gate Driving Signal Sense Voltage B3 Sense Signal Voltage Conditioning Sense B4 Voltage B5 Sense Single Chip MUX Processor ADC Voltage B6 Sense Voltage Sense B7 Voltage Sense B8 Voltage Sense B9 Voltage Sense B10 Voltage CrBlock diagram of control unit Sense
16. Start Charging Wait for Tvdp Read battery voltage, Vn Yes For all n, Terminate charging Voltage Vn=VfullDetecting No Phase 1 N Vavg n 1 Vn N No For any n Vn > V avg Yes Activate PWM module n, calculate duty ratio Reset ta ChargeBalancing For activated modules, process Phase PWM signals Yes ta < tcep Control flow chart No
17. SOFTWARES• MATLAB• Orcad• EdSim51
18. PROJECT PLANNINGRESEARCH ACTIVITY JAN FEB MAR APR MAY JUN JUL AUG SEP DISDiscuss FYP title withsupervisorTitle submission andpresentationLiterature reviewThesis dissertation 1(Ch. 1, 2 and 3)Project SimulationExperimental setupExperimentalimplementationResult discussionThesis dissertation 2(Ch. 4, 5 and 6)Report submission /Final Presentation