Optimal Design Of Thermal Management System Based On Evolution Of Battery Parameters

With the increasing awareness of environmental protection,electric vehicles,as the main means of transportation to replace oil-powered vehicles,are occupying an increasing market size.As the only power source of electric vehicle,the performance of power battery pack directly or indirectly affects the safety,reliability and comfort of the vehicle.Battery is very sensitive to temperature and the battery which works in a reasonable temperature range will maintain the best output performance.High temperature not only reduces the output capacity,will also destroy the internal chemical reaction process resulting in irreversible damage.In more serious conditions,the high temperature will cause the battery heat out of control leading to a large number of battery heat gave off in a short time to cause serious security problems.In this paper,combined with the main parameters of a vehicle’s power battery pack,the thermal management system is configured for the battery pack to achieve unified control and deployment of battery heat and maintain temperature of battery pack in reasonable range while battery pack working.According to the advantages and disadvantages of various cooling methods,the indirect liquid cooling method is selected as the heat dissipation method of the thermal management system.Firstly,the development history of power battery pack and the research status of battery thermal management system are introduced,and the battery heating principle and heat transfer process are analyzed.Experiments are designed to calculate the basic physical parameters of single battery and test the internal resistance characteristics.The numerical model of the single battery is established to carry out the simulation calculation.The definition of the heat source of the battery is realized through UDF programming and the reliability of the established battery thermal model is verified by comparing the experimental results with the simulation results.Secondly,the thermal management systems of different channel are designed base on battery pack and CFD solution are carried out on ANSYS Workbench platform.The evaluation parameters of these thermal management systems,such as the lowest temperature,the highest temperature,the temperature difference and the temperature standard difference,are compared to conclude that the thermal management system with the longitudinal in-line channel has the best heat dissipation performance.Then,under the optimal thermal management system structure,the multi-objective optimization of the geometric parameters of the system was carried out,and the sensitivity of the output targets to the design parameters and the response surface results were analyzed.Finally,characteristic test experiment and verification test are designed based on the simulation process of single battery and battery pack.The experiment equipment involves the constant temperature and humidity test chamber,paperless recorder,Newware battery test system and UIP Intelligent peristaltic pump.The experiments include the battery discharge experiment at different rates in constant ambient temperature,the influence of different ambient temperatures on battery parameters at specific discharge rates,and the verification test of the multi-objective optimization results.The experimental results agree with the simulation results,which verifies the validity of the 3D model and the reliability of the simulation results.