Rotor retaining sleeve design of 1.12MW high-speed PM machine for shipboard power

Permanent magnets hardly bear the large centrifugal force at high-speed rotation, so protective measures must be taken. Nowadays, using the carbon fiber to bindle permanent magnets are commonly used. In this paper, based on a high speed permanent magnet machine (1.12MW, 18000rpm), theory analysis of rotor stress is verified by 3D finite element method. Rotor strength of three different rotor structures and different materials in pole filler is calculated and compared. Effect of running temperature, rotor speed, retaining sleeve thickness and interference between PMs and retaining sleeve are investigated. A new hybrid protective measure is proposed and analyzed. Carbon fiber retaining sleeve and hybrid retaining sleeve are finally designed and the prototypes of the both rotors are produced. The stress tests of both prototypes running at 22000rpm are carried out.