Comparison of Sleeve Types for Ultra-High-Speed Surface-Mounted PM Motors.

This paper compares the rotor losses and the thermal fields of a surface-mounted PM synchronous ultrahigh-speed motor with different sleeve types. Currently, fiber sleeves and metal sleeves are commonly used. Both types of sleeves have high yield strength. However, they have disadvantages either on rotor losses or on heat dissipation. It is well-known that the fiber sleeve can avoid high eddy current losses, but the thermal conductivity is low. Compared with the fiber sleeve, the metal sleeve has higher thermal conductivity. However, its electrical conductivity is also high which causes high eddy current losses. Hence, this paper compares the two sleeves to provide a reference for the machine designers.