Pole Segmentation Shaped by Sinusoidal, Trapezoidal, and Harmonic Injection PWM for Torque Ripple Reduction in Permanent Magnet Synchronous Machines

The present paper proposes three methods to reduce the torque ripple in Permanent Magnet Synchronous machine by decreasing the cogging torque peak and back-EMF harmonic content. These methods consider the pole segmentation technique, but the distribution and width of the segments are determined by PWM techniques. Sinusoidal, trapezoidal and harmonic injection PWM are assigned to Methods 1, 2 and 3 in that order. This methods can decrease the cogging torque peak and also improve the harmonic content of the back-EMF, thus reducing the torque ripple. Furthermore, the methods were validated by means of a finite elements analysis. Method 3 achieved the best results for both 4‑ and 8‑pole machines, reducing the cogging torque peak by up to 79.53 % and increasing the average torque by 6.43 %. It also reduced the magnet volume in the 4‑pole machine.