Electromagnetic Torque Synthesis From Air-gap Magnetic Field Harmonic for Permanent Magnet Vernier Motor

This paper analyzes the principle of permanent magnet vernier motor (PMVM) electromagnetic torque from the perspective of air-gap flux density harmonics. The tooth permeability is calculated by using the magnetic equivalent circuit (MEC) method. The modulation effect of the stator tooth on the magnetomotive force (MIME) of the armature and permanent magnet (PM) is considered. By analyzing the amplitude-frequency and phase-frequency characteristics of the stator and rotor air-gap flux density harmonics, the relationships between electromagnetic torque and flux density amplitude and phase are derived. The PMVM is simplified into multiple ideal permanent magnet synchronous motors (B)PMSMs) combining with the magnetic gear effect. Moreover, the electromagnetic torque is calculated according to the principle of magnetic field superposition. Finally, the results of analytical calculation and finite element method (FEM) match well, which exactly validates the accuracy of results.