Study On Active Equalization Strategy And SOC Estimation For Battery

Power battery is the core of electric vehicles. Development of battery management technology is the key to the development of electric vehicles. As part of battery management system, equalization of batteries is a key technology to improve the performance of the battery. Active equalization can improve the safety and extend life of batteries, and has the advantages of rapid and energy saving.This dissertation mainly studies the active equalization strategy based on battery SOC(State of Charge), and designs different active equalization strategy for three different working conditions, and applies simulation for each working condition. Some key points in the design of active equalization strategies and the demand of the battery SOC accuracy are analyzed. And the active equalization experiment is carried out under static conditions.Then a SOC estimation method of battery is studied. A second-order equivalent circuit model is used to describe the battery. And SOC of battery is extended to the battery model as a parameter. By using the extended Kalman filter(EKF) algorithm, parameters of the battery model can be estimated. So the SOC of battery is estimated. And the active equalization experiments of charge condition and DST condition are carried out.Finally analyzes active equalization board which use in the experiments.And analyzes the working principle and process of active equalization circuit.The average current of the active equalization circuit at work is calculated. And use a signal switching board to make the active equalization board work properly by writing program.