An Accurate SOC Estimation Method for Lithium-ion Batteries which Considers Thermal Variation

Abstract

This paper discusses an SOC estimation system for lithium ion batteries based on the extended Kalman filter. The accuracy of the estimation is strongly dependent on accuracy of the battery model. We have newly formulated the equivalent circuit model that covers temperature and SOC dependencies. As the result, the error rate of the estimation has been improved significantly. The experimental results show that the new SOC estimation system derives very accurate results for wide range of temperature.