DESIGN AND THERMAL PERFORMANCE ANALYSIS OF A NEW WATER-COOLED STRUCTURE FOR PERMANENT MAGNET SYNCHRONOUS MOTORS FOR ELECTRIC VEHICLES

In order to solve the problem of severe stator winding heating due to the single cool -ing structure of a permanent magnet synchronous motor for electric vehicles, and to further improve the heat transfer capability of the permanent magnet synchronous motor, a new water-cooled structure is proposed in which cooling pipes are placed at the stator yoke to increase the heat transfer area. In order to evaluate the heat trans-fer effect of this new water-cooled structure, this paper takes a 50 kW permanent magnet synchronous motor for electric vehicles as the research object. By establish-ing a 3-D full-domain fluid-solid coupled heat transfer model, setting boundary con-ditions and reasonable assumptions, the full-domain fluid-heat coupled field of the permanent magnet synchronous motors is calculated numerically, and the fluid-flow characteristics and heat transfer variation laws of the new water-cooled structure are analyzed. The results show that compared with the original cooling structure, the maximum temperature drop of stator winding and permanent magnet can reach 5.23% and 11.17%, respectively. The results obtained can provide a reference for future research on the thermal performance and water-cooled structure optimization of permanent magnet synchronous motor for electric vehicles.