Maintaining Average Torque and Suppressing Torque Ripple With T-Shaped Auxiliary Pole for Spoke Type Multi-Consequent-Pole Motor

Abstract

A novel stator structure for spoke-type multi-consequent-pole motors was proposed in this paper. While spoke-type multi-consequent pole motors were effective to improve torque density, it was necessary to allow for torque ripple increasing due to the non-uniform magnetic flux density in the air gap. Although torque ripple could be reduced using the I-shaped auxiliary pole reported in the previous study, worsen in average torque was needed to be tolerated. In the proposed motor, T-shaped auxiliary poles were placed on the stator to maintain torque and reduce torque ripple. The point of the proposed motor lies in the magnetic circuit in which the stator coil was divided into upper and lower coils, and the leakage flux, which was generated in the previous auxiliary pole, could be picked by the lower coil. To validate its effectiveness, numerical verification was conducted using the verification model and obtained results were compared with the conventional motors. Moreover, experimental verification was conducted using prototype motors. From the results, it was confirmed that torque ripple could be reduced without decreasing average torque by using the proposed stator structure.