Torque Ripple Suppression of a PM Vernier Machine From Perspective of Time and Space Harmonic Magnetic Field

In this article, a V-shaped permanent magnet vernier (V-PMV) machine is proposed for potential direct-drive applications, where the research efforts are focused on realizing torque ripple suppression. The key of the study is to suppress torque ripple from the perspective of time-space characteristics of PM and armature magnetic motive force (MMF) harmonics. With guidance of the time-space modulation mechanism, the MMF harmonics related to torque and torque ripple are, respectively, determined. Next, the harmonics are designed from two aspects of PM and armature magnetic fields. In the PM magnetic field, a rotor-pole shaping technology is used, where the unique is to introduce a permeance modulation function. It aims at suppressing PM MMF harmonics related to torque ripple and maintaining the MMF harmonics related to torque. To the armature magnetic field, the MMF harmonics are improved by using a winding configuration with star-delta hybrid connection, in which the purpose is to weaken the specific order MMF harmonic effectively. In addition, the performances of V-PMV machine are evaluated, including the airgap harmonic analysis, torque, torque ripple, and so on. Finally, a prototyped machine is built for validating the proposed V-PMV machine and investigated design method.