Overview
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Shrink fitting is a procedure in which heat is used to make a very strong
joint between two pieces of metal such as frame and stator. In this case,
the stator is inserted into the frame by extending the radius of the frame
using heat. The stress caused by shrink fitting is known to affect the
iron loss and magnetic circuit. So, it is important to include the effect
of thermal stress in iron loss analysis and magnetic field analysis.
This note presents the use of structural analysis and magnetic field analysis
to obtain iron loss density of an SPM Motor by taking into account the
stress caused by shrink fitting. |
Compressive Stress Distribution
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Figure 1 shows the compressive stress distribution. The compressive stress
is caused by the shrink of the frame in the radial direction and increases
around the slot. This is because the stress decreases towards the tip of
the teeth, meanwhile the stress is concentrated around the slot. |
Iron Loss Density Distribution
| Figure 2 shows the iron loss density 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 The iron
loss increases when the thermal stress is applied. This is because the
iron loss increases when the thermal stress is applied. To obtain more
accurate iron loss result, the thermal stress caused by shrink fitting
needs to be taken into account in the analysis. |
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