Effect of rotor sleeve conductivity on rotor eddy-current loss in high-speed PM machines

Abstract

Prediction of eddy-current power loss in high-speed PM machines is an important subject, helping the designer to avoid over-heating and maximise efficiency. Studies of a generic form of PM machine show that a conducting sleeve usually reduces losses due to long-wavelength harmonics but increases those due to short-wavelength harmonics. In some operating circumstance total loss is increased. However, in the most important practical circumstances, the presence of a sleeve having a suitable value of conductivity can be expected to be markedly beneficial