Comparison of two battery equivalent circuit models for state of charge estimation in electric vehicles

This study compares two battery equivalent circuits for state of charge (SOC) estimation in electric vehicles (EVs), namely the RC circuit and Thevenin circuit. The state space representations of each circuit are used to develop the adaptive gain sliding mode observers (AGSMO) for the SOC estimations, which are compared with the true SOC. The results show that the Thevenin circuit provides more accurate SOC estimation than the RC circuit. A lithium-ion battery is chosen for experimental verification under constant current discharge and variable current discharge based on EV driving cycles.