AC Copper Loss Separation and Reduction in IPMSM Using Finite Element Analysis

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 proximity effect, such as multiple slots, using aluminum coils, and employing finely divided coil. The results indicated that the reduction rates of the overall copper losses are 21.7%, 23.6%, and 50.1%, respectively.