State of charge estimation of lithium-ion batteries with unknown model parameters

In this paper, a scheme for estimating the state of charge (SOC) of lithium-ion batteries is proposed based on an battery equivalent circuit model. The equivalent circuit model is simplified and the model parameters are treated as unknown values here. An extended Kalman filter (EKF) is designed to online estimate the model parameters and SOC of the battery with a saturation algorithm complemented to keep the estimation of the parameters in a suitable compact subset to improve the estimation performance. Experimental results are provided to demonstrate the performance of the proposed approach.