Research On Simulation And Intelligent Control Of Thermal Management System For Electric Vehicle

With the increase of car ownership in the whole country and even in the world,the problems of energy shortage,environmental pollution,emission stringency,strategic orientation and so on have caused different countries to shift the direction of automobile development to new energy vehicles,especially pure electric vehicles.New energy vehicles have become the next competitive focus and development engine of the automobile industry.This paper mainly designs a vehicle thermal management system based on intelligent algorithm,which can make the power system work at the appropriate temperature to improve motor efficiency.It also can heat the power battery at low ambient temperature and cool the power battery pack at high ambient temperature to ensure driving reliability,reduce energy consumption and increase endurance mileage.Firstly,Based on the thermal management development of a brand pure electric vehicle,the performance and temperature variation of lithium power battery monomer at different temperatures and charge-discharge ratios are obtained through the test method.According to the test data,the physical parameters of power battery monomer and the functional expressions of ohmic internal resistance on temperature and SOC are fitted,and then the heat generation rate formula is obtained based on the heat generation rate formula.The rate formula is simulated by CFD with UDF heat source assignment method to get the temperature rise calculation results at different rates.The heat generation rate formula is verified by comparing the experimental data.Then,according to the parameters of the whole vehicle,the paper matches the important parts of the thermal management system,designs the thermal management scheme of the whole vehicle and builds the cooling model of the motor part and the battery pack considering air conditioning refrigerationt in one-dimensional CFD software.The outlet temperature of the motor and the inlet temperature of the battery pack under different driving conditions are obtained.The simulation model is validated by comparing the wind tunnel test data of the whole vehicle,and the influence of element change on the performance of heat management system is validated and determined.The next step is to determine the control objects of intelligent algorithm,electronic fan and electric compressor.Finally,with a one-dimensional CFD model,the paper obtains the reasonable rotational speed of the electronic fan and the electric compressor under different operating conditions and generates the sample data of the rotational speed of the electronic fan and the electric compressor.The regressive SVM intelligent algorithm(SVR)is used to train and predict the two sample databases to verify the predictive accuracy of the SVR model.Embedding the SVR model in the one-dimensional CFD simulation software,operating the NEDC condition,the paper obtains the change of the outlet water temperature and the inlet water temperature of the battery pack controlled by SVR.After compared with the simulation results of threshold control,the result shows that the heat management system based on SVR control can reduce the power consumption of the electronic fan and the electric compressor on the basis of meeting the temperature requirements,which has good feasibility.