Rotor Design and Analysis of a High Speed Permanent Magnet Synchronous Motor for Cryogenic Centrifugal pump

Due to the advantage of high power density and small size, high-speed permanent synchronous magnet motor(PMSM) is becoming attractive in many industrial applications. Most permanent magnets(PM) are brittle materials, which cannot withstand centrifugal force caused by high-speed operation, so they need to be protected by retaining sleeve. In this paper, the design and analysis of rotor of a high-speed PMSM with rated speed of 100,000 rpm and rated power of 10.5 kW is investigated. First, analytical solution of equivalent stress between PM and sleeve during operation is analyzed. Then, interaction of rotational speed and radius on rotor equivalent stress is studied. In the end, by analyzing the relationship between the calculated shrink fit and the equivalent stress, the optimal numerical value of the shrink fit is determined, which meets the mechanical stress requirement of PM and sleeve.