Simulation and Experimental Study of Oil Injection Cooling for PMSM With Hairpin Winding
Ying Xie, Guoliang Qi, William Cai, Xiangmin Zhao, Yi Zhang, Zebing Wang, Yanhui Yang
Abstract
Recently, the power density of permanent magnet synchronous motor (PMSM) with hairpin winding for electric vehicles was increasing. While the performance of the motor will be limited by the high temperature rise. As a result, oil cooling methods with higher cooling efficiency are widely used. In this paper, an oil injection cooled hairpin winding PMSM with rated power of 55kW is designed. The fluid field of the oil cooling structure under different oil injection hole diameters and arrangements are analyzed by the CFD method. In addition, a resin hosing with the cooling channel is built by 3D printing methods, and the nozzle on the housing is replaceable. An experimental platform for measuring flow rate is also established, the accuracy of the simulation analysis is verified by the experiment. Besides, unlike traditional equivalent methods, a winding model close to real situation is established, which can accurately reflect flow state of cooling oil at winding ends and greatly improve the accuracy of temperature field calculation. On this basis, the motor temperature distribution at different oil injection effects is analyzed and compared. Finally, the optimal injection hole diameter and arrangement of cooling structure is determined, which significantly improve the cooling efficiency.