锂离子电池温升特性分析及液冷结构设计

针对电动汽车动力电池的温升发热导致温度分布不均及过热现象，根据电池的热物性参数及不同环境温度下的内阻，建立电池包生热分析模型；测试采集并拟合电动汽车的母线电流，通过仿真分析得到不同车速下电动汽车电池包的温升情况；进行典型城市工况实车试验，测取不同车速下电池包内温度测点的温升数据并拟合成温升曲线，通过仿真与试验结果对比，验证所建立的热分析模型的准确性；在此基础上，设计双进双出的液冷散热管道结构方案，分析在1C放电倍率下该液冷散热方案的散热效果. 研究结果表明:锂电池在高温（50 ℃）下，内阻仅为13.9 mΩ，而在低温（?30 ℃）时，内阻却达到了21.5 mΩ；电动汽车在新欧洲行驶工况（NEDC工况）和匀速工况（40、50、60、70 km/h）下的最高温升分别为1.8、2.6、3.6、5.3、8.0 ℃；所设计的U型结构液冷管道可以有效地降低电池包温升，提高电池包的温度均匀度. 

Temperature Rise Characteristic Analysis and Liquid Cooling Structure Design of Lithium Battery

Concerning the phenomenon of uneven temperature distribution and excessive temperature of power battery heat generation in electric vehicles, the thermal analysis model of the battery package was established on the basis of thermal physical parameters of the battery and internal resistance at different temperatures. The bus current value of the electric vehicle collected by the test was fitted, and then the temperature rise of the battery package in different driving speeds could be obtained by the simulation. Finally, the vehicle test on typical urban conditions was conducted to measure the temperature rise dates of the test points in the battery package at different constant speeds, and then the curves were fitted by the temperature rise dates. The comparisons between the simulation and the test verified that the thermal analysis model was accurate and effective. On the basis, the double inlet and double outlet liquid cooling pipe structure scheme was designed to analyze the cooling effect of the liquid cooling scheme at the 1C discharge rate. The results show that the internal resistance of lithium battery is only 13.9 mΩ at high temperature (50 ℃), while it reaches 21.5 mΩ at low temperature (?30 ℃); the maximum temperature rise of electric vehicle under new European driving cycle (NEDC) and constant speed conditions (40, 50, 60, 70 km/h) reach 1.8, 2.6, 3.6, 5.3, and 8.0 ℃ respectively; the U-shaped structure liquid cooling pipe can reduce the temperature rise of battery pack effectively and improve the temperature uniformity of the battery pack.