Comparison of the First Order and the Second Order Equivalent Circuit Model Applied in State of Charge Estimation for Battery Used in Electric Vehicles

Abstract

In this study, the first order model and the second order equivalent circuit models of NiMH battery for electric vehicle were used to determinate the battery state of charge. Different parameters for equivalent circuit models were explained. There are four phases in the battery change and discharge, which are charge phase, change idle phase, discharge phase, discharge idle phase. All of these phases are discussed and analyzed. For different phases of charge and discharge, mathematical relationships between parameters and state of charge were built. The calculation results fit well with the experimental results. A precision comparison between the first order model and the second order model was undertaken.