| Under the great pressure of energy and environment,electric vehicle has been widely concerned by the automobile industry.Power battery is the core of electric vehicle,and its working performance is greatly affected by temperature.When the temperature is too high,battery life and safety will be significantly reduced.When the temperature is too low,the electrochemical reaction rate decreases,the capacity of the battery decreases,and the working performance decreases.Therefore,it is necessary to control the operating temperature of the power battery pack to ensure that it always works within the optimal temperature range.This paper mainly studies the thermal management system of lithium ion power battery pack and designs the scheme of contact liquid cooling system.The main work of this paper is reflected in the following aspects:(1)The thermal characteristic parameters of ternary lithium-ion battery were calculated,the thermal effect model of single battery was established,and the effects of discharge rate,convection coefficient and ambient temperature on the temperature field of single battery were analyzed.The validity of the simulation analysis results is verified by the monomer temperature rise test.(2)According to the power requirements of a miniature pure electric vehicle,the battery pack group design was carried out,and the number of series and parallel cells in the battery pack and the group mode were determined.The contact liquid cooling system was adopted,and the transformer oil was used as the cooling medium to heat the battery pack.(3)Based on Fluent software,the temperature distribution of the battery pack with single channel heat dissipation structure was simulated,the influence of cooling factors on the heat dissipation performance of the battery pack was analyzed,and the cooling system was optimized.The results showed that the heat dissipation performance of the liquid cooling system was greatly improved after optimization,but the temperature consistency of the single channel heat dissipation structure was poor.(4)Based on the simulation results of the single-channel heat dissipation structure,three feasible multi-channel heat dissipation structures were proposed,and the heat dissipation performance of the cooling systems of the three structures was simulated and compared.The results showed that the heat transfer and velocity characteristics of the battery pack A structure were superior to the other two.(5)A pure electric vehicle model is built based on AMESim,and the heat dissipation and heating performance of the battery pack A structure in the driving process is simulated and analyzed by taking the cycle conditions of NEDC and US06 as examples.The results show that the designed liquid cooling system can control the temperature of the battery pack in a reasonable range and the temperature distribution is uniform in both high and low temperature environments.In the whole cycle,the heat dissipation and heating performance of the automobile battery pack are good,and the system structure design is reasonable. |
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