| To solve the increasingly serious problem of environmental pollution and fossil energy shortage,vehicle electrification has becomefocus and hot spot in automobile industry development.With the gradual development of electric public transport in China,the electrification of fuel vehicles will have a great market demand.In this process,the design of the vehicle’s electric power system and power battery cooling system is facing greater challenges due to the continuous increase in vehicle mileage requirements.Based on the passenger car model used as a taxi,this paper designs and analyzes the energy system and battery thermal management system in the process of oil-to-electricity reform.The main conclusions can be extracted as follows:(1)The lithium-ion battery test-bench is built based on the test software platform of Neware.The performance of the square lithium-ion battery of AVIC 2614894 selected by the modified vehicle is tested.The temperature rise and internal resistance of the cell under different environmental temperature and discharge rate,as well as the relationship between the temperature influence coefficient of voltage and electromotive force and SOC are obtained,andit lays a foundation for the research of thermal characteristics of battery cell.(2)Based on the Bernardi battery heat production calculation empirical formula,a dynamic heat production rate model of lithium-ion battery with respect to temperature and SOC change is established by using the performance test results of single battery.The dynamic battery heat production model is programmed and loaded in ANSYS FLUENT software by using UDF,andthe process of 0.5C,1C,2Crate discharge aresimulated to analysis the thermal characteristics of the batteryunder theenvironmental temperature of 10℃,20℃,30℃,40℃.Finally,the accuracy of the dynamic heat generation model and the reliability of the numerical simulation method of the thermal characteristics are verified by comparing the simulation results with the experimental test results.(3)Based on the mileage and power requirements of the selected vehicle,the theoretical calculation of the total power demand of the vehicle battery assembly was performed.The number and connection method of the battery cells in the battery assembly were determined according to the performance parameters of the battery cells.On this basis,the AMESim simulation software was used to build the dynamic model of the vehicle,the rationality of the power system design was verified,and the heat production of the battery under various operating conditions was calculated to provide the data support for design of the battery thermal management system.(4)Based on the basic theory of hydromechanics and heat transfer,the basic dimensions of the liquid cooling plate and its internal cooling channel are designed,and the power design of PTC for water heating in battery heat management system is carried out,when the maximum thermal production power of the battery is taken into account under the condition of 15% climbing.Based on ANSYS-Fluent software,the temperature field and flow field of the battery modules with different flow channel structures are simulated and analyzed,and the cold plate structure with better cooling effect is selected.Finally,on the basis of the selected cold plate structure,the module layout and cooling pipe connection design of the battery assembly are carried out,and the liquid cooling circulation flow of the battery assembly is simulated and analyzed.The results show that,under extreme heat-generating conditions,the maximum temperature of the single cells is 38 ℃,the temperature difference of the single cells between the modules is within 1 ℃,and the maximum average temperature difference of the battery modules in the assembly is within 2 ℃.The above results show that the battery liquid cooling system designed in this paper has good cooling performance,which can control of the highest temperature of the battery and the temperature difference of the single battery and meet the design requirements of the vehicle cooling system. |
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