Abstract: In order to improve the accuracy of SOC estimation during the use of traction lithium-ion battery for meeting the requirements of battery management system for battery monitoring, a SOC estimation method for traction lithium-ion batteries at different temperatures is proposed. Firstly, through comparative analysis on control algorithm models, the second-order equivalent circuit model is selected,and according to the results of multiple temperature point experiment, the parameters of battery are fitted and a temperature-based battery parameter model is built. Then according to the improved extended Kalman filtering algorithm, a SOC estimation model is established. Finally, a rapid control prototyping simulation is carried out with DST and FUDS cycles to verify the robustness of the algorithm at different temperatures. The results show that the SOC estimation algorithm formulated can not only suppress the interference of current noise, but also make the estimated SOC value speedily converge to the real one when its initial value has a large error, with its error kept within 0.04 in the whole process of estimation.

Key words: traction Li-ion battery, temperature-dependent battery model, state of charge, rapid control prototype