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.