The SOC estimation method of lithium ion battery used in electric vehicles under aging condition

Extended Kalman filter（EKF） algorithm is often used to perform battery State-of-Charge（SOC）estimation. This method is based on the equivalent circuit model, so model accuracy plays a key role for estimation results. With the aging of the battery, the internal resistance increases, and the accuracy of the model decreases.The influence of the battery aging on the SOC estimation accuracy is experimentally investigated, and a correction method is proposed. The test results show that the SOC algorithm considering battery aging significantly improve the prediction accuracy.