State-of-Charge estimation for power Li-ion battery pack using Vmin-EKF

An accurate estimation of State-of-Charge (SOC) for power battery pack is very important in the applications of electrical vehicles. Single cell model is not suitable for battery pack of m u Iti cells. Considering the imbalance characteristic of serial connected battery pack, a V_min model is proposed. The minimal cell load voltage of the battery pack (V_min) is used as the model measurement variable, and SOC is used as the model state variable. Based on the V_min state space model, the extended Kaiman filter (EFK) approach is applied to get the recursive estimation of the battery pack´s SOC. Experiments were made to simulate the behaviors of battery pack in the driving conditions. The results showed that accurate and real-time estimation of SOC could be obtained through this approach.