Overview
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The laminated structure of the core can be maintained by press fitting or shrink fitting. When a magnetic steel sheet is used for the core of a motor, the stress caused by press fitting is known to affect the increase of iron loss. So, the press-fitting stress needs to be taken into account in iron loss analysis.
This example presents the use of a structural analysis and magnetic field analysis to obtain the iron loss density of an SPM motor with and without press-fitting stress.
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Compressive Stress Distribution
| Figure 1 shows the compressive stress distribution and Figure 2 shows the
tensor display. The stress in the yoke is stronger than that in the frame
and teeth. Especially, the stress is concentrated at the yoke facing the
slots. This is because the stress decreases towards the tip of the teeth,
meanwhile the stress is concentrated around the slots. As shown in the
tensor display, the compressive stress is dominant around the slots and
the tensile stress is dominant in the frame. |
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Iron Loss Density Distribution
| Figure 3 shows the Iron loss distribution. The iron loss density distribution is significantly affected whether the stress is applied or not. The result shows the 15 percent increase of the iron loss when the stress is applied. This is because the iron loss increases when the compressive stress is applied. To obtain more accurate iron loss result, the compressive stress caused by press fitting needs to be taken into account in the analysis.
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