Research on the Magnetic Field Modulation Effect of PMVM from the Perspective of Armature Magnetic Field

The permanent magnet vernier machine (PMVM) is featured with high-torque density due to the magnetic field modulation effect. At present, the analysis of the magnetic field characteristics and harmonic torque of PMVM is mainly derived from the perspective of permanent magnet (PM) field modulation. The research on armature magnetic field modulation is very limited. Therefore, this article studies the magnetic field modulation from the perspective of armature magnetic field, revealing the relationship between armature magnetic field and output torque. The process of armature magnetic field modulation and PM magnetic field modulation is compared and analyzed. It was found that in PM field modulation, the fundamental wave of PM magnetomotive force is modulated into different spatial harmonics with the same frequency; whereas in armature magnetic field modulation, the harmonics of different armature magnetomotive force are converted into temporal harmonics with identical frequency. Then, based on the perspective of armature magnetic field modulation, a new PMVM is proposed to improve torque. Compared with the existing uniform split teeth topology, the torque of the new PMVM is increased by 32%. Finally, a prototype of the machine has been manufactured and tested to verify its effectiveness.