Influence of the Air-gap Length and Semimagnetic Wedges on the Performance of a High-Speed Synchronous Reluctance Motor with an Axially Laminated Anisotropic Rotor

Abstract

The impact of the air-gap length and usage of semimagnetic wedges on the performance of a synchronous reluctance motor (SynRM) with an axially laminated anisotropic (ALA) rotor aimed at high-speed applications was studied. The studied ALA rotor is intended to be manufactured by heat treatment of a stack of special magnetic and nonmagnetic materials. A 12 kW, 24000 rpm motor is considered in the study. An increase in the air-gap length can significantly reduce the rotor eddy current losses and stator iron losses. However, because of a lower magnetizing inductance with a larger air gap, the supply current is higher resulting in higher stator winding Joule losses. Along with the air-gap length analysis, the semimagnetic wedges were considered as a way of mitigation of high-order harmonics of the air-gap flux density. Wedges with a high relative permeability allowed to improve the efficiency of the machine. The case with realistic semimagnetic wedges was studied (having standard relative permeability values). Both air-gap length adjustment and semimagnetic wedges can be used to improve the efficiency of an ALASynRM.