On the Design of a PMSM Rotor with Ferrite Magnets to Substitute a Rare Earth Permanent Magnet System

Abstract

In this paper, the design of a permanent magnet synchronous machine (PMSM) with spoke type rotor and ferrite permanent magnets (spoke-type PMSM) as a substitute to an existing PMSM is presented. The reference machine is a fractional horsepower interior PMSM with v-shaped NdFeB-magnets (VPMSM). The spoke-type PMSM is designed based on the geometrical properties of the reference machine. The characteristic of the machines in two operating points are compared; one in the base speed area and one in the field weakening range. The foci of the comparison are the electrical and mechanical properties of the machines, e.g. back-emf, torque, radial force densities and iron losses. The effect on the machine's cost by using different materials is analyzed.