Battery evaluation, modeling and fast charger using supercapacitor as input source.

摘要

Different batteries have been evaluated to check their capability in Electric vehicles. The evaluation is performed on 30Ah Lithium Ferro Phosphate battery cells from Gold Peak. Different tests (charge- discharge cycle, fast charging test, realistic load test) are done on battery cells. Tests are done at 0.0°C, +20.0°C, +40.0°C. Current, voltage, and temperature are recorded throughout the tests. During cycle test, constant current mode exerts exothermic reaction and constant voltage mode exerts endothermic reaction. A-h efficiency and W-h efficiency are analyzed for different current rates at different temperatures.;Model of lithium polymer battery is presented. Model parameters are temperature and state of charge dependent. One whole block is dedicated to state of charge calculation. This block is able to autonomously detect the transition from charge to discharge and vice versa. Also if charging or discharging current stops flowing, it resets the current integrator initial condition to the last state of charge calculated. Comparison between experimental and model results showed about 3% maximum error in dynamic (interval test) response and 5% error in static response of battery discharging (until 10% state of charge is left in the battery).;The Supercapacitor (SC) model was developed using Matlab/Simulink. Different charging and discharging tests are performed on the SC to extract the model parameters. Detailed dynamic as well as static behavior of the SC is studied to extract the one branch (R-C) model instead of two branch model with little modification. The model was verified experimentally.;A novel static switching (made up of MOSFET and DIODE in series) structure is implemented. This switches charges and discharges four supercapacitors sequentially. Both the simulation and experimental results are presented.;At last the fast charger is implemented, which takes the input from SC through above mentioned static switches. The charger implemented is of flyback topology, which provides the great range of duty control, as current source in particular battery charging application. Three converters work in parallel to provide the charge rate upto 3C. The whole system as well as system components is described in detail. Charger functions are discussed and implemented.