Simulation Analysis And Optimization Of Heat Dissipation Performance On Power Battery Of FSEC Pure Formula Electric Racing Car

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.