Research On Thermal Analysis And Liquid Cooling Control Of Electric Vehicle Power Battery

The performance of power battery under high temperature for a long time will be damaged.Therefore,liquid cooling is selected in this dissertation to conduct heat dissipation for the battery module,in which the flow rate will affect the heat dissipation effect.Small extremely coolant flow rate can lead to higher overall temperature of the battery module,while large extremely can increase the energy consumption of the coolant pump.The energy consumed by the coolant pump is supplied by the battery.The more energy consumed by the pump,the less energy the battery provides to the electric vehicle,resulting in the reduction of mileage.Therefore,this dissertation designs a coolant flow rate selection method,which can not only make coolant pump consume less energy,but also effectively control the temperature of the battery module.The main work and contributions can be summarized as below:Firstly,this dissertation takes the ambient temperature and discharge rate as variables to carry out the capacity,temperature and HPPC experiments on the single battery.The heat generation model is established by substituting the internal resistance results into Bernardi model.Secondly,the single battery simulation takes discharge rate as the only variable to analyze the temperature characteristics.By comparing the maximum temperature of the battery obtained by the two methods,the maximum deviation is not exceeding 5%,so the heat generation model is proved to be reliable.Taking the battery module composed of 48 batteries in parallel as the research object,using serpentine cooling pipe,the cooling characteristics of liquid cooling system under different coolant flow rate,discharge rate and temperature are studied.Finally,based on the optimal coolant flow rate under different ambient temperatures and discharge rates obtained by simulation,the selection formula of flow rate is designed,and the formula is optimized by designing the fitting function.The battery module is simulated for variable speed,climbing and variable temperature,and the cooling system uses two velocity selection formulas.After comparative analysis,the maximum temperature and maximum temperature difference of the battery module are slightly higher than those before the optimization,but both meet the requirements.And the coolant pump energy consumption can be reduced by 22.5%,24.64% and 33.86%respectively under various driving conditions,when the optimization formula based on the fitting function is used in the cooling system.