Joint Estimation of SOC and SOH for Lithium Batteries based on DEKF

The accuracy of estimation of SOC and SOH of lithium battery can affect the control strategy of the electric vehicle battery management system, which affects the life of the battery. The paper uses equivalent circuit to simulate the model of battery, and adopt the Least Square (LS) method to recognize the parameters of model. Conduct the experiment on battery by the mix of charged and discharge condition, use the state Kalman Filter (KF) to estimate SOC of battery. Use Parameter Klaman Filter and the Least Square Method with forgetting factor respectively to estimate the resistance of battery in order to estimate of SOH of battery. The fitting function of OCV-SOC adopts Gaussian function. The paper verifies that estimation of battery by Kalman Filter doesn't rely on the initial value of SOC, also verifies the feasibility of Double Extended Kalman Filter (DEKF).