Analytical computation of magnetic field distribution in double-stator hybrid-excitation vernier motor based on an accurate subdomain model

The double-stator hybrid-excitation vernier motor (DSHEVM) is a type of low-speed high-torque motor. The establishment of an accurate mathematical model of the DSHEVM, accurate determination of the magnetic field distribution, and an explicit physical relationship between the design parameters and the output torque are the keys to multi-objective optimization. This study proposes an accurate DSHEVM subdomain model to obtain precise magnetic field distributions. This subdomain model considers the effects of the relative permeability of the permanent magnets, split-pole slots, and stator slots on magnetic field distribution. The governing equations of the seven subdomains are established in scalar magnetic potential. According to the boundary conditions and corresponding Fourier series expansion at the interface of each subdomain, the magnetic flux density distributions in the main subdomains are obtained, and the output torque of a DSHEVM is analyzed. Based on the finite element method and experiments, the calculation accuracy of the proposed subdomain method is verified. The findings of this study provide a basis for multi-objective optimization and precise analysis of loss and temperature field of the DSHEVM.