Analysis Of Temperature Field And Cooling System Of Electric Vehicle Hub Motor

The hub motor of electric vehicle is needed to meet the requirements of high power density and high torque density in a limited space because of its special operating environment.Therefore,the loss per unit volume is relatively large.At the same time,under different working conditions,the size and distribution of motor loss are different,it has a great influence on the temperature rise distribution of each part of the motor.Therefore,the effective cooling method is very important for the hub motor.Accurate analysis and improvement of temperature rise of hub motor under different working conditions is of great significance to the stable operation of electric vehicles.In this paper,the actual driving conditions of electric vehicles permanent magnet hub motor are studied,and a series of analytical calculations are carried out.Firstly,the loss of stator winding,rotor core,stator core and permanent magnet of PMSM are calculated and analyzed.Based on the different working conditions of the electric vehicle such as constant speed,flat-road high speed,overload slope climbing and accelerating overrun,the loss calculation and analysis under the rated working conditions and different working conditions are carried out,the regulation of loss change under different torque and different speed is studied,and effective measures of loss reduction are taken.Secondly,the three-dimensional calculation model of hub motor is established,and the cooling scheme is designed,including axial water-cooling and spiral water-cooling structures.The fluid structure coupling analysis of the motor is carried out.Under the rated condition,the reasonable cooling scheme is determined by comparing the temperature rise of each part of the motor under different cooling structures,at the same time,the transient temperature field of the motor under different working conditions and the temperature changes at different parts at different times are calculated and analyzed to provide a reference for the calculation of temperature field of high power density hub motor under different working conditions.Finally,according to the selected axial water cooling structure,the effects of different number of channels,channel width and cooling medium flow rate on the temperature rise of each part of the motor are studied,and the effects of parameter changes on the flow state and pressure difference are analyzed.Through the improvement of motor end cover structure to reduce the winding end with the highest temperature rise,the cooling capacity of the motor is improved,which provides a reference for the improvement of cooling structure of electric vehicle hub motor.