Comparative Multiphysics Analysis of Ultra High Speed PMSM Rotor Designs

Solid permanent magnets are commonly used in the rotors of ultra‐high‐speed permanent magnet synchronous motors (PMSMs). However, standard rotor designs are subject to assembly difficulties and high manufacturing costs that are not conducive to large‐scale production. The present work addresses this issue by proposing an integrated rotor structure composed of a retaining sleeve and ring‐shaped permanent magnets with a rotor core that yields an ultra‐high‐speed PMSM operating at 95 krpm under 25 kW of power. Firstly, electromagnetic finite element analysis is conducted for rotor design schemes with different permanent magnet, sleeve, and rotor core materials to determine the optimal outer rotor core diameter based on the maximum current of the applied converter, and the electromagnetic performances of the schemes are compared. Secondly, the rotor design schemes are subjected to mechanical finite element analysis to obtain stress distributions under different temperatures. Finally, the rotor design scheme applying NdFeB permanent magnets, a carbon fiber sleeve, and a Ti‐alloy rotor core is identified as providing optimal eddy current loss, temperature, tangential stress, and vibrational characteristics that surpass those of PMSMs applying conventional rotor designs. © 2026 Institute of Electrical Engineers of Japan and Wiley Periodicals LLC.