Novel Analytical Method for Overhang Effects in Surface-Mounted Permanent-Magnet Machines

The torque and power densities of surface-mounted permanent-magnet (SPM) machines can be improved significantly using an overhang structure. However, it is difficult to analyze and design SPM machines with overhang because a 3D finite-element method (FEM) that uses high computation time is required to consider the overhang effects accurately. To reduce the computation time significantly, we propose an analytical method in which a magnetic equivalent circuit (MEC) model and an analytical solution (AS) of the Laplace and Poisson equations are combined. This method can accurately estimate the performances of SPM machines with overhang as well as significantly reduce the computation time compared with that required for the 3D FEM. The accuracy and generality of the proposed method were verified by comparison with the 3D FEM in different cases.