Research On Heat Dissipation Structure And Air Supply Strategy Of Lithium-ion Battery Module For Electric Vehicles

With the continuous transformation and development of our country’s social economy,new energy vehicles will become the mainstream of the development of the automobile industry,and its market share will gradually increase.Lithium-ion battery is the core of electric vehicle energy storage,and temperature is one of the main factors affecting the performance of the battery.Due to the lack of timely heat dissipation,the automobile accidents caused by excessively high battery temperature occurs from time to time.Therefore,the problem of effective heat dissipation of lithium-ion batteries for electric vehicles needs to be solved urgently.In the thesis,the heat generation model of the battery cell and the simplified model of the battery module are established.The simulation and analysis of the temperature field are completed,and a new heat dissipation structure of the lithium-ion battery module is designed.The temperature field and flow field simulation are carried out to study the influence of the battery spacing and the air velocity of the air inlet on the heat dissipation characteristics.Finally,the variable speed reciprocating air supply strategy with different time intervals is proposed.The optimization design of the heat dissipation strategy is carried out under the NEDC condition,and its simulation experiment verification is completed.The main research contents of the thesis are as follows:1.Analyzing the current domestic and foreign heat dissipation structure of lithium ion battery module and cooling strategies,the lithium-ion battery of pure electric car is chosen as the research object.The working principles of the battery are studied such as the calculation,the heat transfer mechanism and the theory of heat production rate.The research paths are planned on the heat production model of the lithium ion battery monomer,the heat dissipation structure of battery module and the air supply strategy of the system.2.Based on the internal resistance and the temperature entropy coefficient of the lithium-ion battery with SOC variation,the heat generation model of the lithium-ion battery is established.The accuracy of the model is verified by the simulation experiment of lithium-ion battery at different discharge rates and relevant parameters for the heat source setting of battery module are provided.3.Based on the cell arrangement,the inlet and outlet positions,the traditional parallel cooling ventilation of lithium-ion battery module structure is improved.The temperature coefficient and the temperature uniformity coefficient are set to evaluate the effect of the structure.Compared with the traditional structure,the effectiveness of the structure is verified and the main influencing factors of the heat dissipation efficiency are analyzed.4.The variable speed strategy of the reciprocating air supply with the different time intervals is proposed and the comparative analysis with the traditional heat dissipation strategy of the continuous air supply is completed.Based on the battery heat production under the NEDC condition of the electric vehicles,the heat dissipation strategy is designed.It is ensured the timely and effective heat dissipation while the energy consumption of the heat dissipation is reduced.The simulation verification is completed.The research provides valuable reference for the development of battery management system of electric vehicle.