| With the development of electric vehicles in the future,the lithium battery of electric vehicles,as the source of power,plays a very important role.Lithium ion batteries need to adapt to different working environment and driving conditions when they work,which will cause the phenomenon of heat accumulation in the battery pack under certain working conditions,and the temperature will continue to rise,so that the battery can not meet the optimal working temperature,which will lead to the decline of battery performance,and even lead to heat out of control,which will bring a series of security risks.In order to effectively solve a series of problems caused by the battery pack in some working conditions,it is particularly important to study the heat dissipation technology of lithium-ion battery pack.In this paper,105 ah square lithium iron phosphate battery is selected as the research object,and the battery thermal management system is systematically studied by the methods of theoretical research,experimental analysis and numerical simulationFirstly,the basic principle of lithium-ion battery is studied,and its basic structure,working principle and heat generation performance are analyzed to provide a theoretical basis for further research;the thermal performance of lithium-ion battery is analyzed,and the internal resistance of the battery is tested through HPPC test,and the heat generation is calculated according to bernadi formula,and then the cell is simulated at different temperatures and rates by numerical simulation method Analysis,summed up the heating situation.Then,according to the requirements of vehicle performance parameters,the 2p60 s lithium-ion battery group structure is designed,and two kinds of liquid cooling plate with different flow channel structure are designed,which are evaluated from the heat dissipation efficiency,temperature uniformity and energy consumption.After comprehensive consideration,the liquid cooling plate of scheme 2 is selected.Based on the vehicle working conditions,the performance of lithium-ion battery group is analyzed,and the vehicle model is built through AMESim to analyze the static performance of the vehicle The output current,SOC change and real-time heat generation power of lithium-ion battery under NEDC condition are mainly described.Finally,the thermal management performance of Li ion battery pack with liquid cooling system is studied,and the working conditions of high temperature fast charging,low temperature heating and high temperature NEDC are analyzed.The results show that the temperature of lithium-ion battery pack can be effectively controlled under high-temperature and fast charging conditions,the maximum temperature of the battery after charging is30.8 ℃,and the temperature difference is 2.3 ℃;under low-temperature heating conditions,the battery temperature rises from-20 ℃ to 2.7 ℃ within 900 s,and the heating efficiency is 1.51 ℃ / min;under high-temperature NEDC conditions,the maximum temperature of the battery pack is 37 ℃,and the temperature difference is 2.58 ℃.Therefore,the lithium-ion battery pack can effectively meet the thermal management performance under three working conditions.The lithium-ion battery pack heat dissipation technology studied in this paper can not only provide new ideas for the modular heat dissipation theory innovation of pure electric vehicles,but also improve the economy of pure electric vehicles and the driving range,which has certain practical significance.. |
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