关键词: 锂电池低温容量损失模型, 安时积分法, 低温荷电状态估算

Abstract: The maximum available capacity of lithium-ion battery decreases at low temperatures, which impacts the low-temperature state of charge (SoC) estimation accuracy directly. The maximum available capacities of LiFePO₄ battery are tested at different temperatures, a linear low-temperature capacity loss model and a constant low-temperature capacity loss model are proposed to analyze and compare the different trends of capacity losses of batteries with temperature under these two models, and the effects of these two low-temperature capacity loss models on SoC estimation are compared based on the ampere-hour integration method. The two SoC estimation methods are compared by MATLAB/Simulink simulation and real-vehicle low-temperature charging and discharging tests. The results show that the linear low-temperature capacity loss model has higher estimation accuracy, with SoC estimation errors of 1.81% and 3.64% in the vehicle low-temperature charging and low-temperature discharging tests, respectively, and the SoC does not change with the battery temperature when the battery is resting, which is more in line with the expectations of end customers.

Key words: lithium-ion battery low-temperature capacity loss model, ampere-hour integration, SoC estimation at low temperature