Tooth-Ripple Losses in Highspeed Permanent Magnet Synchronous Machines

Abstract

Highspeed Permanent Magnet Synchronous Machines (P. M.) become more and more popular for their small weight and low noise. As the residual magnetism of rare-earth magnets is temperature dependent, eddy-current losses in the supporting-ring of radial-airgap constructions play an important role in the design of such machines. This paper presents a solution for the harmonics, due to slotting, in the flux-density waveform on the surface of the supporting-ring, using a Fourier-Series-Method. A fast approximate solution for loss-calculations at no-load is shown and the results are compared with measured values of an experimental machine, rated at 1000kW, 1250V, 15000rpm.