Simulation and implementation of State-of-Charge estimation of power lithium-ion battery using energy method

Battery is the major energy storage source of electric vehicles (EVs), which makes the accurate estimation of State-of-Charge (SOC) very crucial. Various SOC estimation methods have been proposed in recent years. Among of them, Ah method is widely used due to its easy implementation. This paper presents an energy method for SOC estimation of power lithium-ion battery, which is based on the law of energy conservation. The mathematical model is firstly built to describe its principle. A MATLAB-Simulink simulation model and a laboratory prototype are established to verify the performance of the energy method. Simulation and experimental results show that this SOC estimation method is more accurate than the Ah method, especially under high current and variable current conditions.