Estimation the residual capacity of Ni-MH battery pack using NARMAX method for electric vehicles

This paper presents a nonlinear autoregressive moving average with exogenous variables (NARMAX) method to estimate the residual capacity of high-capacity Ni/MH battery pack in electric vehicles. The state of charge (SOC) represents the battery residual capacity. The SOC of battery cannot be measured directly and estimated from measurable battery parameters such as current and voltage. The proposed NARMAX produces accurate SOC estimate, using industry standard Federal Urban Driving Schedule (FUDS) aggressive driving cycle test procedures. The results indicate that the NARMAX can provide an accurate and effective estimation of the SOC, resulting in minimal computation load and suitable for real-time embedded system application. The maximum average relative error of the estimating results is 0.02%.