Analytical Modeling of Surface-Mounted PM Machines Accounting for Magnet Shaping and Varied Magnet Property Distribution

This paper develops an analytical model for predicting the magnetic field, back-electromotive force (EMF), and electromagnetic torque of surface-mounted permanent magnet machines accounting for magnet geometrical shaping and varied magnet property distribution. The magnets on the rotor are represented by the remanence, thickness, and magnetization direction functions. They are finitely segmented into magnet pieces of simple regular shape and uniform magnet property. The magnetic field of the machine is obtained by the superposition of the magnetic field due to each segment. The back-EMF and electromagnetic torque are also calculated. Using the developed model, the technique of mixed magnet material is investigated on a four-pole/six-slot machine. The analytical predictions are verified by both finite element and experimental results.