Analytical Performance Calculation of Vernier Hybrid Machine with Subdomain Method

Abstract

The analytical subdomain models of vernier hybrid machines with two kinds of permanent magnet (PM) arrangements are developed, and the magnetic vector potentials are considered unknown variables to obtain the no-load and on-load magnetic field in this article. According to the electromagnetic properties and machine structure, the entire solving region is divided into five subdomains, namely the stator slot, slot opening, PM, air gap, and rotor slot. Using the general solutions of magnetic vector potentials and boundary conditions, the magnetic field distributions of all subdomains are obtained. Then the air gap flux density, flux linkage, back-EMF, cogging torque, electromagnetic torque, unbalanced magnetic pulls, and PM loss are calculated and compared for the two models. With the analytical model, the PM demagnetization withstand capacity, effects of main parameters on the torque ripple and average torque, and combinations of PM and rotor slot numbers are also studied. The 2D finite element method and experimental results of two prototype machines validate the accuracy of the analytical models.