H infinity observer based state of charge estimation for battery packs in electric vehicles

A H infinity observer based method is proposed to estimate the state of charge (SOC) for a series-connected battery pack for electric vehicles. In this method, an average virtual cell (AVC) model is defined and the SOC of the AVC model is estimated to represent the pack SOC when all terminal voltage differences (TVD) between each individual cell in the pack and the AVC are within a voltage value set in advance. The LiFePO4 battery pack is utilized to conduct the experiments to verify the effectiveness of the proposed method.