Torque Ripple Reduction Method With Asymmetric Pole for Wound-Field Synchronous Motor

This paper deals with an effective reduction method of torque ripple by adopting novel asymmetric pole structure of wound-field synchronous motor. In general, skewed pole structure of a rotor is used to reduce torque ripple despite decreasing an average torque. This paper introduces the design parameter of shift angle of an asymmetric pole-plate for effective elimination of torque ripple. In addition, the design can maintain the length of field winding compared with skewed pole structure, which means low copper loss in field winding and low material cost. In addition, average torque can be increased at the same input voltage over the driving region as well. The 2-D finite element method is used for the analysis of proposed model and skewed model. For the comparison of characteristics between the skewed model and proposed model, skewed pole with three steps is introduced with low torque ripple.