Overview
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When a motor has magnet overhang, the flux is generated both in the in-plane
direction and the lamination direction, which then increases the iron loss.
To evaluate the loss increases caused by the overhang, those caused by
the flux in the in-plane direction and those by the flux in the lamination
direction need to be separated.
This note presents the use of a no-load iron loss analysis of an SPM motor
with and without overhanging magnet. |
Flux Density Distribution
| Fig. 1 shows the flux density distribution of the stator core, and Fig.
2 shows the flux density distribution in the lamination direction. Since
the overhanging magnet increased the flux in the in-plane direction and
the lamination direction, the flux density is higher around the surface
of the stator core. |
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Closeup |
Eddy Current Density Distribution
Closeup |
Fig. 3 shows the eddy current density distribution. The eddy current generated
around the surface of the tooth tip penetrates in the lamination direction
because the overhang increases the flux in the lamination direction. |
Iron Loss Comparison
| Fig. 4 shows the eddy current loss and the hysteresis loss generated by
the flux both in the in-plane direction and the lamination direction. Fig.
5 shows the amount of the loss increases caused by overhang. The overhanging
magnet increases the loss caused by the flux in the lamination direction
as well as the loss caused by the flux in the in-plane direction. |
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Closeup |
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