Studies on Design Approach for Downsized and Weight-Reduced Permanent Magnet Motors utilizing Less Heavy Rare-Earth Elements

用于高功率密度的小型化、轻量化永磁电机的稀土磁体需要具有较高耐热性能的重稀土元素作为添加剂来保护其退磁。为了减少添加剂，电机结构的设计方法是重要的，其中包括考虑永磁体热分布的快速计算。研究并开发了基于热电路网络的永磁体热分布计算方法，该方法采用有限元磁场分析得到的损耗计算方法。与有限元热传导分析方法相比，该分析方法在保持计算精度不变的情况下，计算时间缩短了百分之一。

The rare-earth magnet used in downsized and weight-reduced permanent magnet motors with high power density requires heavy rare-earth elements as additives providing with higher heat-resisting property to protect its demagnetization. For reducing the additives, a design approach for motor structure is important, in which a fast computation considering thermal distribution on permanent magnet is involved. We studied on and developed the thermal analysis approach for computing thermal distribution on permanent magnet, which was based on thermal circuit network and used losses obtained from finite element magnetic field analysis. Compared with heat conduction analysis by finite element method, the developed analysis approach made it possible to reduce its computation time by one-hundredth while keeping its computation accuracy same.