Analytical Modeling of Slotted, Surface-Mounted Permanent Magnet Synchronous Motors With Different Rotor Frames and Magnet Shapes

Abstract

This article presents an analytical solution procedure to investigate the geometrical impact of the magnet and the rotor core on the performance of slotted, surface-mounted permanent magnet (PM) synchronous motors. In particular, four different motor configurations with loaf-shape/regular arc-shape magnets mounted on the octagon/circular rotor surface are investigated, and their no-load (i.e., PM flux density, back EMF, and the cogging torque) and on-load (i.e., armature flux density, winding inductance, and electromagnetic torque) performance metrics are compared. The analysis is carried out analytically by using the concept of the surface magnetization current (SMC) and the superposition theorem. First, the stator slots are nullified, and Poisson's equation is solved on a slot-less surface. The effect of the stator slots is then included by injecting equivalent SMC on the stator bore. For verification purposes, analytical results are validated via the finite element (FE) and experimental measurements on the motor prototype.