Cogging Torque Reduction Using Magnet Phase Inverted Shape in Dual Axial Gap Motor

This paper describes the design of permanent magnets for dual axial gap motors to reduce cogging torque. In this method, a radially segmented and circumferentially shifted skewed shape is designed and placed in the lower part of the rotor axial direction. The phase inverted shape, which is designed by inverted the phase of the skewed shape with respect to the central axis, is placed in the upper part of the rotor axial direction. This cancels the cogging torque waveforms generated in the upper and lower axial directions. Furthermore, the magnet shape was optimized to maximize the cancel effect. First, the cogging torque waveform was predicted from the magnet shape, and then a shape was selected that satisfied the cancelable conditions and analyzed using 3DFEM. As a result, a magnet shape that reduces cogging torque by 94.6% was obtained.