Study on the Influence of Internal Water Cooling System on the Loss of Permanent Magnet Synchronous Motor

Better cooling scheme is of practical significance for the research and development of Permanent Magnet Synchronous Motor (PMSM) with higher power density. In view of a surface embedded PMSM which has an outer rotor, an internal water cooling (IWC) scheme is proposed. The reasonable waterway arrangement and connection is proposed based on the slot electrical potential star graph, aiming at restraining the circulation current loss in the parallel waterways. Then the analytic formula of the eddy current loss in the copper tube is deduced by the idea of micro-element, and the position and thickness of copper tube are optimized based on the analytic formula. Finite element method (FEM) results has verified the rationality of both the proposed connection scheme and the rationality of the optimizations for the location and thickness of copper tube. The contents of this paper are of reference value for improving the PMSM power density by using IWC method.