Characteristic Analysis and Modeling of LiFePO4 Battery

In order to achieve an accurate estimation of the state of charge of LiFePO4 battery, a corresponding accurate model needs to be established. Through charging and discharging experiments on LiFePO4 battery under different charge and discharge rates, it is found that different current rates have a great influence on the battery voltage, and the influences of charging and discharging are inconsistent. An improved equivalent circuit model, based on current rates and current direction, is proposed to accurately simulate the dynamic characteristics of LiFePO4 battery under different current rates. The parameters of the improved equivalent circuit model were identified offline in terms of experimental test data, and the simulation model of the equivalent circuit was established in MATLAB. The equivalent circuit model was simulated under different current rates, and then contrast the simulation results and experimental test results with that of the old one before improvement. The contrasting results show that the improved equivalent circuit model do a better job in simulating the dynamic performance of LiFePO4 battery, thus effectively reduced the model error and improved the model accuracy.