Research on SOC estimated strategy of Ni/MH battery used for hybrid electric vehicle

On the basis of the pulse charge and discharge characters of the nickel-metal hydrogen battery (Ni/MH) used for hybrid electric vehicle (HEV), a real-time and dynamic SOC estimated strategy of Ni/MH battery is presented in this paper. The initial SOC of the battery is determined by the historical factors and the current status together and the internal resistance of the battery is taken into account. Then the SOC of the battery is jointly calculated by the coulomb-accumulation contribution and open-circuit-voltage contribution based on the modified RC model, in which the efficiency of charge and discharge and the transient effects of the battery are considered. Finally, the validity of the SOC estimate strategy is tested by experiments, the results shows a great accuracy of SOC estimated by the new method, which is fit for the request of the HEV well.