Research On Liquid Cooling Thermal Management System Of Li-ion Battery Module For Electric Vehicle

Lithium ion batteries have been widely used in electric vehicles because of their high energy density,long cycle life and low self-discharge rate.Its service performance,safety performance and service life are closely related to temperature.The lithium-ion battery pack in electric vehicle produces rich heat in the process of high rate charging,and faces the problems of uneven temperature distribution and high local temperature.High temperature will accelerate the battery aging,even cause the battery thermal runaway.The thermal management system of electric vehicle is one of the key technologies to deal with the related problems of battery heat and ensure the operational performance,safety and service life of power battery.The performance of the thermal management system has an important influence on the aging and safety of the battery under the condition of high rate charging.Liquid cooling thermal management system is widely used in electric vehicles due to its excellent performance.The battery pack of an electric vehicle is composed of multiple battery modules connected in series and parallel.During the operation of the vehicle,the thermal management system has the same heat dissipation effect on each battery module.Therefore,it is very representative to study the performance of the system from the perspective of battery modules.Thermal analysis of battery is the basis of the study of thermal management system.In order to accurately analyze the thermal production of battery in the process of high rate charging,the basic parameters of battery capacity,internal resistance,entropy coefficient,specific heat capacity and thermal conductivity are tested in this dissertation.On this basis,combined with the theory of cell heat generation and heat transfer,a single cell heat generation model is built.In addition,an experimental method is designed to test the heat generation of battery charging.Then,taking the thermal management system of lithium-ion battery module as an example,a liquid cooling platform is established,and the relevant experimental scheme is developed to analyze the influencing factors of the cooling performance under the liquid cooling mode.Finally,for the condition of high rate charging of electric vehicle,combined with the relevant parameters of battery heat generation,heat generation model and the analysis results of influencing factors,the cooling capacity of power battery liquid cooling thermal management system is evaluated.