2025 Volume 14 Issue 6 Pages 818-823
This paper attempts to separate the AC copper loss, which is significant in high-speed electric motors, into four elements: the skin effect, the in-slot proximity effect, the inter-slot proximity effect, and the effect from permanent magnets. It is found that 84.6% of the AC copper loss in the interior permanent magnet synchronous motor (IPMSM) investigated in this study is caused by the in-slot proximity effect. Furthermore, several countermeasures are presented to reduce the in-slot and inter-slot proximity effects, such as multiple slots, employing finely divided coils, and using aluminum coils. The results demonstrate that the reduction rates of the overall copper losses are 9.0%, 50.1%, and 23.6%, respectively. Furthermore, by combining the three countermeasures, copper loss is finally reduced by 62.5%.
