Investigation of Magnet Shape Design Methods to Cancel Cogging Torque in Double Axial Gap Motor

Abstract

　This paper proposes the optimization of magnet shape combination and cogging torque cancellation method for a double rotor-single stator axial gap motor. Since the two axially opposite surfaces are torque-generating surfaces, the motor is expected to generate a high torque density in a flat structure. Cogging torque is a major issue because it determines the quality of the motor. Previously, the authors proposed the magnet in the shape of multiplicative wave and confirmed that it is useful for reducing cogging torque. In this study, the combination of the multiplied-wave magnet shapes in the top and bottom rotors was optimized to cancel out the harmonic components of the cogging torque generated between each gap. As a result, the cogging torque was significantly reduced while maintaining the same torque.