Reducing Torque Ripple Using Axial Pole Shaping in Interior Permanent Magnet Machines

This article compares various design techniques for torque ripple reduction using a commercial industrial interior permanent magnet machine (IPMM). These design techniques include the traditional skewing, radial pole shaping, and the proposed axial pole shaping. The new axial pole shaping technique achieves a particular flux concentration pattern on the rotor surface along the axial direction through shaping the pole arc radially and axially. The flux concentration pattern was optimized using the differential evolution algorithm. All three design techniques are implemented individually in the same commercial IPMM design. The performance of all the techniques was simulated using finite element method. The comparative study shows that the proposed axial pole shaping can reduce the torque ripple effectively with minimum torque reduction compared to the other two traditional techniques. The predicted results were validated experimentally through a variety of tests in which the measurements show reasonably good agreement with the predicted performance.