Research On Thermal Management System Of Lithium Power Battery For New Energy Vehicles

Global issues such as climate warming,environmental deterioration and scarcity of fossil fuels are increasingly attracting people's attention.With their advantages of energy saving,environmental protection,and low noise,new energy vehicles have gradually evolved from concept to industry and have been flourishing in recent years.As the main source of energy for the current new energy vehicles,power batteries are its most important link.In addition to the requirements for high energy density,good rate capability,long cycle life,and long driving range,the power battery must be fully guaranteed.The safety problem of the battery is essentially a problem of heat and temperature.If the heat generated by the battery during operation cannot be dissipated in time,resulting in excessively high temperatures,the battery performance will rapidly decline and the lifespan will be degraded,probably which may further cause the battery thermal runaway,causing fire and severely threatening the personal and property safety.Therefore,it is very necessary to study the battery thermal management system.In this paper,a square aluminum-shelled ternary lithium-ion battery is studied.The theoretical analysis,numerical simulation and experimental testing are combined to study the thermal characteristics of the battery and the heat dissipation structure of the module.The main work is as follows:First of all,we fully understand the main research contents of the battery thermal management system and the research status of various technical routes through the domestic and foreign related literature,and introduce the structural characteristics,working performance of lithium-ion batteries and their differences in thermal safety.The working principle,heat generation and heat transfer characteristics of lithium-ion batteries are analyzed to provide a theoretical basis for subsequent research.Secondly,the thermal parameters and the heat generation rate of the battery are calculated,and a three-dimensional thermal model of the battery is established.According to the simulation results of the temperature field of the battery cell and the module,the front and back surfaces of the battery are determined to be the best heat dissipation surface.Elucidating the results that equal heat dissipation area and equal flow status are the key to ensure the thermal balance of the module.Subsequently,based on the above-mentioned points,two modules based on parallel air-cooling heat dissipation are designed,and their cooling effects are compared by CFD fluid dynamics simulation.The results show that the proposed step-by-step module structure saves space and enhances the system energy density.At the same time,it still has good heat dissipation performance,which provides a certain reference for practical engineering applications.Finally,through the battery charge and discharge test,the relative relationship between the battery performance parameters and temperature is explored to provide the necessary supplements and instructions for the full text.The battery thermal model is verified by the data of battery temperature rise at different rates of discharge at 25°C.The results show that the model can accurately simulate the temperature distribution,the terminal temperature and the process temperature of the battery.