【作者】 杨勇；

【导师】 李红； 凌亚；

【作者基本信息】 扬州大学 ， 工程硕士（专业学位）， 2020， 硕士

【摘要】 2013年,中国大学生纯电动方程式汽车大赛(Formula Student Electric China,FSEC)正式成为中国大学生方程式汽车大赛(Formula SAE,FSAE)的常设类别。FSEC因其赛事特点,使得动力电池在比赛过程中产生大量热量,为避免积聚的热量对电池性能产生高温影响,设计一种FSEC电池散热管理系统对于提高赛车的安全性和可靠性尤为必要。本课题结合单体电池生热及电池组风冷散热仿真与赛事工况不同倍率放电试验,以FSEC电池组散热管理系统为研究对象,从单体电池生热到电池组传热和散热为主要研究路线,选择最高温度、最低温度及最大温差为优化评价指标对风冷散热系统的结构进行优化设计。首先介绍了聚合物锂离子电池的组成成分、工作机理及工作时的热量产生来源,建立了单体电池热模型,对电池密度、比热容及热导率等热物性参数进行了等效处理,并确定了单体电池各部分的热生成速率数值模型。其次运用CATIA、ANSYS等软件对单体电池进行了三维建模和有限元处理,并按FSEC动态赛事项目划分的三种工况(循环耐久工况、短时大电流放电工况、完全放电极限工况)进行了相关参数设置且进行了热仿真。搭建了适用于单体电池温度采集的平台进行了试验,对比仿真与试验的温度验证了单体电池热模型的可靠性和准确性。然后基于单体电池各项参数,初步设计了电池包的总布置方式。结合循环耐久和大电流短时放电工况所散发的热量进行散热风扇选择,在双散热风扇散热系统中对循环耐久放电工况的两个循环放电周期及大电流短时放电工况进行了初步散热仿真,仿真结果表明有多种因素对散热效果产生了显著影响。本文最后通过正交试验设计多因素多水平的优化方法,在首次正交设计时对单体电池间隙等13个因素的3个水平安排了仿真试验方案并展开仿真计算。在计算完成后又通过最高温度、最低温度及最大温差三个优化评价指标进行较优方案的确定。在首次正交设计优化后的较优方案下,最大温差的优化程度达到了 21.127%。然后再次进行正交试验设计,因素数与水平数根据前次结果的影响程度进行减少,反复安排进行,最后优化后的最大程度接近40%,在对实车进行调试后验证其可靠性。综上所述,本文所设计的FSEC电池风冷散热系统,能够有效降低电池在各工况下的温度积聚现象,为纯电动赛车的进一步设计提供了一定的技术参考。更多还原

【Abstract】 In 2013,Formula Student Electric China(FSEC)officially became a permanent category of Formula SAE(FSAE).Due to the racing characteristics of FSEC,power batteries will generate a large amount of heat during the race.In order to avoid the accumulation of heat on the battery performance of high temperature impact,a FSEC battery thermal management system is particularly necessary to improve the safety and reliability of racing car.This subject combines the simulations of the heat generation of cell and air cooling heat dissipation of battery pack with the discharge test of different power ratio in the race conditions,takes the heat management system of FSEC battery as the research object,from the heat generation of cell to the heat transfer and heat dissipation of batteries as the main research route,and selects the maximum temperature,minimum temperature and maximum temperature difference as the optimization evaluation indexes to optimize and improve the structure of the air cooling cooling system.Firstly,this paper introduces the working mechanism,composition and the heat source of polymer lithium ion battery and the thermal model of cell was established.The thermal physical parameters such as density,specific heat capacity and thermal conductivity were treated equally,and the numerical model of the thermal generation rate of each part of cell was determined.Secondly,CATIA,ANSYS and other softwares were used to conduct 3d modeling and finite element modeling of the cell,and relevant parameters were set and thermal simulation was carried out according to the three conditions(Cyclic durable discharge conditions,Short-term high current discharge condition,Complete discharge limit condition)divided by FSEC dynamic event project.A platform suitable for temperature acquisition of cell was built and the reliability and accuracy of the thermal model of cell were verified by comparing the temperature of simulation and experiment.Thirdly,based on the parameters of cell,the overall layout of the battery pack is preliminarily designed.Combined with the heat emitted from the Cyclic endurance condition and the Short-term high current discharge condition,the cooling fans were selected.In the dual-cooling fan cooling system,two cycles of Cyclic durable discharge condition and the Short-term high current discharge condition were preliminarily simulated.The simulation results show that many factors have a significant efect on the heat dissipation.Finally,the multi-factor and multi-level optimization method is adopted to design the multi-factor and multi-level optimization method through orthogonal experiment.In the first orthogonal design,the simulation experiment scheme is arranged and the simulation calculation is carried out for 3 levels of 13 factors,such as the gap of single battery.After the calculation is completed,the optimal scheme is determined by three optimization evaluation indexes:maximum temperature,minimum temperature and maximum temperature difference.Under the optimal scheme after the first orthogonal design optimization,the optimization degree of the maximum temperature difference reached 21.127%.Then,the orthogonal test design was carried out again,and the number of factors and horizontal numbers were reduced according to the influence degree of the previous result.The maximum degree after optimization is close to 40%,and the reliability of the vehicle is verified after debugging.In conclusion,the FSEC battery air cooling system designed in this paper can effectively reduce the temperature accumulation of the battery under various working conditions,providing a certain technical reference for the further design of pure electric racing car.更多还原