Optimal overhang structure considering overhang effects in the axial flux permanent magnet motor

In this paper, the overhang structure, which has been used in the radial flux permanent magnet motor, was applied to the axial flux permanent magnet (AFPM) motor. Moreover, the overhang effect was investigated for different overhang structures. Because the AFPM motor has an enlarged form along radial direction, the leakage flux and the saturation effect are considerably different at inner and outer radius of the stator. Therefore, inner and outer overhang part could have different overhang effects. This can lead to the optimization problem with optimal overhang length. Because the AFPM motor requires 3D finite element analysis from its 3D structure, an efficient optimization algorithm is required for optimal overhang structure. In order to increase the convergence speed of the optimization algorithm, this paper proposed the gradient assisted contour method.