RASP methods for achieving low torque pulsation in spoke-type PM motors

This paper proposes a new structure using reshaped assisted salient pole (RASP) methods to reduce the torque ripple of spoke-type permanent magnet (PM) motors. During the structure improvement process, the size of the PMs remains unchanged, and the suitable object is the rotor core. First, the suppression of flux density harmonics by the ASP is demonstrated. For lower torque pulsation, the inverse cosine reshaped (ICR) ASP method is proposed. For higher average torque, the third harmonic is injected into the ICR ASP to generate the ICR + 3 ASP. Depending on the RASP method, it is possible to optimize the flux density harmonics, especially the harmonics that cause first-order torque pulsation. When compared with existing forminroposed method can achieve lower torqu and higher average torque. Finally, a prototype is manufactured and experimentally tested to demonstrate that the proposed RASP methods can provide low torque pulsation.