Summary

Here we analyze the cogging torque of a permanent magnet motor in three dimensions to investigate the effect of the coil end.

Explanation

This analysis can be performed in the same way as the two-dimensional calculation ("Two-Dimensional Cogging Torque Analysis for Permanent Magnet Motors"), using the data pre_geom2D and rotor_mesh2D used for the two-dimensional analysis, extended in the z-direction with 2D_to_3D. The file input is almost the same as in the two-dimensional case, but the z-directional extension must be specified by 2D_to_3D. Fig. 1 shows the variation of the magnetic field intensity distribution with angle, which is not so different from the two-dimensional case, and the three-dimensional effect is considered to be small. Between the rotor and stator, the magnetic field intensity is slightly smaller at the coil ends. Fig. 2 shows the angular dependence of torque as well as the two-dimensional case. It can be seen that the torque is slightly smaller due to the end effect. This is closer to the actual measured value.

Fig.1 Variation of magnetic field strength distribution

Fig.2 Angular dependence of torque
(Comparison between 2-D and 3-D)