Optimization and thermal analysis of less-rare-earth interior permanent-magnet synchronous machines used for electric vehicles

The electric vehicles become increasingly popular duo to their characteristics of energy efficiency and environmental protection. The motor used in the electric vehicles is usually the permanent magnet synchronous machines (PMSM). In recent years because of the price fluctuations of the rare earth, the less-rare-earth interior permanent-magnet synchronous machine (LRE-IPMSM) has attracted more and more attention because of its high performance and low cost. In this paper, a investigated LRE-IPMSM is optimized with respect to the width of the bridge and the span angle of the permanent magnet (PM) slot. The losses are calculated at base and maximum speed work points, and then the temperature field of the investigated LRE- IPMSM is analyzed to make sure the PMs and the winding work at the safe temperature range.