Scalability of SPM Bearingless High - Speed Motor for 180 – 280 kW Applications

Abstract

This paper presents the design of the optimization of multi-phase, 25000 rpm 180 – 280 kW SPM bearingless motors. The electromagnetic analysis investigates motor and suspension performance with high-quality silicon and iron-cobalt lamination materials. Structural rigidity of surface and buried permanent magnet motor structures made of said materials are compared. The main challenge in bearingless motor design is achieving high efficiency with possibility to control suspension forces. Motors of the same volume with different stator slot shapes, slot openings, tooth shapes, magnet thicknesses and angles are investigated. The main objectives of optimization are the minimization of torque ripple, force ripple, force error angle and efficiency. The design is optimized in FEM analysis. Power and performance limitations of selected geometries are investigated and discussed.