Oil-water Composite Cooling Method of Hub Motor for Electric Vehicles

Hub motor has poor heat dissipation conditions limited by the installation space and working environment, high temperature rise in the process of operation has been a bottleneck to further improve the power density and torque density. The increase of power density means the increase of motor loss density and the acceleration of motor temperature rise, which will accelerate the aging of internal insulation materials and reduce the reliability of the motor to a certain extent. The cooling effect of traditional water jacket cooling is limited, and it cannot meet the cooling requirements of hub motor more and more. Taking hub motor for special vehicle as the research object, the cooling structure of rotor oil cooling and compound water jacket cooling are designed. The heat inside the motor is mainly carried away by the lubricating oil and water in the form of heat conduction and convection heat transfer. ANSYS software was used to build a 3d model of the motor, to simulate the temperature field of the motor, and to analyze the temperature distribution inside the motor under different working conditions. The low-speed high-torque, one-hour temperature rise test of the motor prototype was carried out on a bench built in the laboratory, and the test results were compared with the simulation results of the temperature field, showing a good consistency, which verified the rationality of the model.