Hysteresis modeling for estimation of State-of-Charge in NiMH battery based on improved Takacs model

This paper describes about the electrical modeling of NiMH battery to estimate the state-of-charge (SOC). The relationship between the SOC and the open circuit voltage (OCV) has the hysteresis characteristic and it is modeled based on the Takacs model in this paper. The modeling includes both of major loop and minor loop. The original Takacs model is improved with additional polynomial function to approach the experimental data as similar as possible. To verify the improvement by using the proposed Takacs model, the results of the original Takacs model and the improved one for the major and minor loops are compared. The modeling error in major loop based on the improved Takacs model is less than 4% SOC. In minor loop modeling, the error of modeling is less than 6% SOC, but there is no significant difference with the improved Takacs model.