271 – Axial Gap Type Motor AC Copper Loss Analysis

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Model Data


The primary loss of axial gap type motors occurs in the core, magnets, and coils. This document focuses on the loss that occurs within coils.
Coil loss can be defined in accordance with both DC copper loss and AC copper loss. It is entirely possible to calculate DC copper loss with relative ease from the coil geometry, electrical resistivity, and the current. Conversely, AC copper loss is influenced by the likes of magnetic fields generated by conductors that are positioned close together. There are instances of using square wire to increase the coil fill factor, but in this circumstance, because the coil wire cross section is large, the current is easily distributed, and making estimates from calculations done manually can prove difficult.
By using finite element analysis, coil loss can be visualized, and analysis is made entirely possible without the need for prototyping any real machines.
In this example, the AC copper loss of an axial gap type motor using square wire is evaluated.

AC Copper Loss

Coil AC copper loss is shown in Table 1, and coil cross section loss density distribution and magnetic flux density distribution are both shown in Fig. 1.
It can be understood from Fig. 1 that loss becomes larger in the vicinity of the air gap. It can be considered that the distribution of loss occurs due to flux leakage in the vicinity of the air gap linking with the coils.

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