Vehicular level battery modeling and its application to battery electric vehicle simulation

Abstract

Battery modeling is a prerequisite for the successful development of the battery electric vehicle. Many researches on the battery modeling methods have been developed on the cell level and showed their good performance. The extension of the battery model to the vehicle level has drawn attention recently. This paper presents at the vehicular level lithium ion battery modeling method, i.e. pack and cell models with 1RC equivalent circuit model, by applying the vehicle chassis dynamometer test. These pack and cell models are cross compared at the same voltage level via scale transformation. Among two model parameters, the battery static parameter open circuit voltage (OCV) is measured by chassis dynamometer test to determine OCV value according to specific state of charge. The battery dynamic parameters R0, R1, and C1 are extracted by nonlinear least square method. The two battery models are validated by experimental testing. The comparison showed that all battery models have similarly high levels of accuracy within the vehicle operation region. These battery models are adopted into the battery electric vehicle (BEV) model, which shows the validity to evaluate various key component parameters of BEV such as motor, battery capacity, battery structure, and driving mode.