Cogging Torque Reduction by Using Double Skew of Permanent Magnets in Axial Gap Motor

This paper describes the reduction of cogging torque by designing the permanent magnets in the axial gap motor. In this method, the side shapes of the permanent magnet are designed as a multiplicative waveform. Then, the optimal shape is obtained by changing the amplitude and the order of the multiplicative wave, which are as a parameter. This is expected to achieve relative skew effect. Furthermore, skew is applied to the designed permanent magnets with respect to z axis to reduce the cogging torque. As a result, by designing the permanent magnets with a multiplicative waveform and using skew, the average torque is reduced by 3.37%, but the cogging torque is reduced by 73.0% and the torque ripple by 60.2%. Thus, the effectiveness of the double skew method was confirmed.