Additional losses in permanent magnet brushless machines

Abstract

The aim of the paper is to analyze the additional Joules losses in permanent magnets. The stator slot openings gives rise to changes in the magnetic flux density in permanent magnets (PM) of the rotor brush-less direct-current (BLDC) machine while the machine is rotating. The final consequence of these changes are induced eddy currents in PM and further additional power losses. The 3D time-stepping finite-element analysis is used to analyze this phenomenon. The induced eddy-current distribution in PM and the resulting power losses are calculated at different number of permanent magnet axial segmentation.