| With the increase of car ownership,the traditional car has brought a lot of energy consumption and environmental pollution.In order to solve the problems of energy consumption and environmental pollution,and promote the sustainable development of the automobile industry,pure electric vehicle become a breakthrough in the development of the automobile industry.As the only power source of pure electric vehicle,the power battery pack determines the vehicle’s performance,reliability,safety and cost.Therefore,the research on the design,thermal management,SOC estimation and control strategy of power battery pack is imminent.During the charge and discharge process,the battery pack will produce a lot of heat.If the heat can not be dissipated in time,the battery pack’s temperature will rise rapidly,and temperature gradient also increase.The high temperature of the battery pack will cause the thermal safety problems of the battery pack.At the same time,the excessive temperature difference will make some of the battery decay more quickly than other batteries,which will aggravate the inconsistency of the battery.These effects will shorten the service life of the battery pack,and ultimately increase the running cost of electric vehicles.Therefore,in order to make the battery pack to play the best performance,the research on the thermal management of battery pack is particularly important.In this paper,the thermal flow field characteristics of the power battery pack will be studied from the point of battery thermal management.In this paper,the working principle,heat generation and heat transfer mechanism of lithium-ion battery were introduced.Then,the discharge capacity and internal resistance of lithium-ion battery at different ambient temperatures were tested.Finally,the heating rate of lithium-ion battery was measured under the different charge and discharge rates and different ambient temperatures.The temperature rise and temperature difference of the battery pack without cooling were calculated by CFD Software.And the simulation result was used to verify the cooling effect of cooling system.In this paper,the air cooling system was designed for the battery pack according to the characteristics of the use of micro-electric vehicles.And analyzed the influence of theinstallation location of the fans,the width of the flow channels,the fan’s speed and the temperature of intake air on the heat flow field of the battery pack.Finally,the design scheme of air cooling heat dissipation was determined according to the simulation results.By using CFD software,the temperature rise and temperature difference of the battery pack were calculated under the uniform condition,climbing condition,charging condition,NEDC condition and different working environment temperature.And the simulation results were used to verify the effectiveness of the wind cooling system.In order to improve the temperature uniformity of the battery,this paper proposed a temperature equalization method.The equalization method was verified and improved by CFD software,and ultimately ensured the ideal temperature equalization scheme.Finally,the temperature equalization scheme and the forced air cooling were used in the battery pack,and the reliability of the temperature equalization scheme was verified by the simulation of the typical working conditions. |
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