Optimization of rotational oil-spray-cooling structure and temperature field analysis of PMSM in vehicle

The heat dissipation of the permanent magnet synchronous motor (PMSM) of an electric vehicle is always worthy of attention, and the design of the cooling system of the PMSM is very important. The rotor rotational oil-spray-cooling structure is widely used in PMSM with hairpin winding. The oil enters from one side of the hollow shaft and is sprayed from the outlets of the front and rear, respectively, which realizes the cooling of the winding at both ends. However, the flow difference on both sides of the shaft will cause the problem of uneven cooling of the winding and the issue of local overheating of the motor. Therefore, the hollow shaft structure needs to be optimized. A 120 kW oil-cooled motor is analyzed as an ex-ample in this paper. The flow field distribution during the rotation of the rotor and the reasons for the uneven shunt are analyzed. The structural parameters of the hollow shaft are optimized by using the Taguchi method and the response surface method. It was found that the new shaft structure can better realize the shunt and reduce the winding and rotor temperature. It provides a guide for the design of the rotational oil-spray-cooling structure of the oil-cooling PMSM.