Research on Thermal Overload Capability Enhancement and Selection Criterion of PMSMs with Phase-Change-Material-Based End-Winding Cooling

To address high end-winding temperature in permanent magnet synchronous motors under overload, this paper proposes a passive thermal management method using phase change material (PCM) in a capsule tightly contacting the windings. The PCM absorbs latent heat in its phase change range, buffering hotspots and retarding temperature rise. An electromagnetic–thermal-coupled model including loss distribution and PCM nonlinearity is built to analyze thermal characteristics under various overloads and PCMs. Results show that, at 2.0 times rated load, the time to reach insulation limit extends from 2500 s to 3500 s. The PCM benefit decreases with higher overload; an optimal phase change temperature exists, rising with overload. Direct placement improves the heat transfer path and suppresses transient hot-spot temperature, depending on selection. Experiments validate the model. This study provides a feasible cooling structure and theoretical basis for enhancing overload capability and thermal design of permanent magnet motors.