Optimization design of the sleeve for high speed permanent magnet machine

Abstract

Permanent magnet (PM) of the high speed permanent magnet machine has to be protected to resist the huge centrifugal force. One of the mature protective measure is to retain the PM with the nonmagnetic alloy sleeve. However, the rotor eddy-current losses would increase meantime. Decreasing the sleeve thickness would reduce the eddy-current losses of the machine but decrease the mechanical strength of the rotor. Thus the retaining sleeve has to be designed optimally and the thinnest sleeve with the enough rotor strength would be preferred. This paper analyzes the rotor strength of the high speed permanent magnet machine and discusses the effect of the sleeve thickness and shrink range on the rotor strength. Base on the above study, the guidelines for optimization design of the sleeve has been summarized and the optimization algorithm has been put forward.