Research on Improved EKF Algorithm Applied on Estimate EV Battery SOC

The paper mainly described how to estimate the state of battery charge (SOC) on electric vehicle (EV). Having deeply researched the lithium-ion (LiFePO4) battery characteristic, the paper established a kind of new battery equivalent circuit model. Meanwhile the paper improved the traditional EKF SOC estimate algorithm, including add the battery internal resistance as a new state variable, real time adjust the observation error variance Rk and add the gain factor to control the convergence speed. Through simulating analysis, the new method estimated error of SOC is less than traditional estimate method.