Analysis of the impact of the method of manufacturing a rotor on the parameters of an AC IPM machine

Abstract

This article presents the technological problem related to the production of rotors with an internal permanent magnet. Most often, the magnetic circuits of such rotors used in alternating current synchronous motors (AC IPM) are made of isotropic magnetic sheets. At this point, it should be noted that it is often not taken into account that each isotropic magnetic sheet exhibits some anisotropy. This significantly affects the operational parameters of the brushless permanent magnet (PM) motor such as the cogging torque, electromagnetic torque ripples and an increase in induced voltage harmonics. To illustrate how important it is to properly design the rotor core, two rotors of the IPM motor were analyzed in this work. In the first rotor solution, minimization of the magnetic sheet anisotropy was not taken into account, and the skew of the magnets was not used. In the second case of the IPM motor, the problem of rotor magnetic circuit anisotropy was minimized and an additional skew of the PMs was used. The obtained measurements and calculations of selected useful parameters of both rotor designs were then compared with each other. Importantly, the conclusions drawn and the resulting comments will prove useful to designers, assemblers and manufacturers of electrical machine components.