Simulation Study On Temperature Rise And Cooling Characteristics Of Electric Vehicle In-Wheel Motor

In the context of the energy crisis and environmental degradation,the development of electric vehicles to replace the traditional diesel locomotive has become a national strategic plan.In recent years,with the strong government support,the development of electric vehicles ushered in a new boom.Wheel motor drive system is a kind of electric drive technology,which is directly driven by the motor mounted in the wheel.It has the advantages of superior power performance,high transmission efficiency,compact structure and easy realization of active control.It is known as the ultimate of electric vehicle drive form.Complicated driving conditions require high power for hub motor,a unique installation location and small installation space requires a more compact and lightweight motor structure,making the hub motor heat production and cooling more severe than other drive motors.Motor insulation materials and permanent magnets on the temperature changes are more sensitive to high temperature rise will cause permanent magnet demagnetization and insulation failure,thereby reducing the motor performance and life expectancy.Therefore,the hub motor temperature and heat dissipation has become the key issues which constraints the development of hub motor.In this paper,an external rotor hub motor as the research object,in-depth study of the hub motor temperature rise and cooling issues.The research of this paper is mainly divided into three parts.The first part mainly carries out the calculation of the motor loss,and the accurate calculation of the motor loss is the basis of the temperature field analysis.Based on the electromagnetic field theory of the motor,the finite element method Lower motor loss calculation and analysis.The results show that with the increase of speed and load factor,the average loss of the motor is on the rise.Therefore,when analyze the temperature field or thermal design,we should pay more attention on the conditions of high speed and large overload.The second part carries on the analysis of the temperature field of the natural air-cooling motor under different working conditions,and carries on the preliminary design of the motor water-cooling system for the overheating condition.Finally,the temperature field distribution and cooling efficiency of the motor under different cooling modes and different cooling structures are compared and analyzed.The results show that the air cooling can only meet the cooling needs of low speed and low load conditions,under high speed and large overload multiple will cause overheating of the motor;Water cooling has a higher cooling efficiency,it is the ideal cooling structure for hub motor.In order to obtain higher cooling efficiency and lower cooling system energy consumption,the third part of the preliminary design of the liquid-cooled structure optimized design.Summarized the impact of cooling medium parameters and the pipeline structure parameters for motor temperature field and cooling system fluid field.