Cogging Torque Cancellation by Magnet Shape Design for Axial Gap Motors

This paper proposes the optimization of magnet shape combination and cogging torque cancellation method for a double rotor single stator axial gap motor. The motor consists of a central stator sandwiched between two rotors from both sides. Since the two axially opposite surfaces are torquegenerating surfaces, the motor is expected to generate a high torque density in a flat structure. On the other hand, cogging torque is a major issue because it determines the quality of the motor. Previously, the authors proposed a method to reduce the cogging torque while maintaining the torque by designing the magnet shape in the shape of multiplying wave. In this study, the authors optimize the combination of the multiplied wave magnet shapes of the top and bottom rotors. In addition, we design a magnet shape that inverts the phase of the harmonic component of the cogging torque generated between the top and bottom rotors and the stator. As a result, the proposed model can significantly reduce the cogging torque while maintaining almost the same torque as the basic model.