Helical retaining sleeve for eddy current loss reduction in high-speed SPM machine

A rotor retaining sleeve is mechanically necessary in the structure of high-speed SPM machines to prevent structural failure. However, significant eddy current loss within metal sleeves leads a reduction electromagnetic efficiency and serious thermal mechanical issues. Therefore, several techniques methods have been proposed developed reduce such losses. In this paper, helical losses by cutting flow path currents. Using FEA, comparison made performance against conventional having same material dimensions. It concluded that reduces significantly when used, whereas stress broadly unchanged central region with only small increase around ends compared sleeve.