| The IWM is installed in the wheel;it needs to meet the requirements of high power density and high torque density.At the same time,because the installation space is narrow and closed,and the air flow is not smooth,which makes the heat dissipation capacity of the IWM poor.If the heat of the IWM cannot be dissipated in time,it will threaten the safety and stability of the IWM drive system and vehicle.Liquid cooling has become the first choice for the cooling system of the IWM because of its good heat dissipation effect and lower cost.And the IWM is installed in the wheels,and the road excitation will act on the IWM directly through the wheel,which will affect the flow field characteristics of the motor’s liquid cooling system,and then affect the thermal field characteristics of the IWM.Therefore,the accurate analysis of the thermal field characteristics of the water-cooled IWM under different road excitation plays a crucial role in the accuracy of the research on heat dissipation of the IWM.Based on the domestic and foreign correlation research result,a 15 k W water-cooled permanent magnet synchronous IWM is taken as the research object in this paper,and the temperature field characteristics of water-cooled IWM under road excitation are studied and analyzed by using finite element simulation method.The main research content of this paper is as follows:(1)Analysis of temperature field characteristics of water-cooled IWM.Based on the heat flux coupling theory,the spiral water-cooled IWM was taken as the research object,and the heat flux coupling analysis model of the water-cooled IWM was established.And the heat generation rate of each component of the IWM under different working conditions obtained by calculation and analysis was loaded into the motor heat flux coupling model as thermal load.And the heat flux coupling model of the water-cooled IWM was analyzed to obtain the temperature field characteristics of the water-cooled IWM under different working conditions.It laid a foundation for the subsequent research on the temperature field characteristics of water-cooled IWM under different road excitation.(2)Analysis of vibration characteristics of IWM under road excitation.The rear-drive IWM was taken as the research object,and the vibration analysis model of the IWM driven vehicle and road excitation model were established.Then,by changing the parameters of the road excitation model,the vibration velocity response characteristics of the stator and casing of the IWM drive system under different road excitation were obtained.It provided a more accurate excitation load for the subsequent study of temperature field characteristics of water-cooled IWM under different road excitation.(3)Analysis of temperature field characteristics of water-cooled IWM under road excitation.Based on the load under different road excitation and the thermal load under different working conditions obtained in the previous study,the temperature field distribution of water-cooled IWM under different road excitation was obtained by changing the driving speed and road grade.Then,the characteristics of temperature field of water-cooled IWM without considering the road excitation obtained in the previous study was compared and analyzed.Finally,the influence law of speed and road grade on the characteristics of temperature field of water-cooled IWM was obtained.(4)Optimal design of cooling structure of water-cooled IWM based on road excitation Based on the heat flux coupling model of water-cooled IWM under road excitation,the multiple regression equation and particle swarm optimization algorithm were adopted.And the channel floor thickness,inlet flow,inlet and outlet diameter,and cooling channel height were optimized variables.The maximum temperature of permanent magnet of IWM,the temperature difference of the rotor and the maximum temperature of the IWM at different speeds on B-grade road surface were taken as the optimization objectives.Then the cooling structure was optimized and the final cooling structure of the IWM was obtained.The flow field and temperature field before and after optimization were compared and analyzed to verify the accuracy of the optimized structure. |
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