Mechanical Analysis With Thermal Effects for High-Speed Permanent-Magnet Synchronous Machines

The high-speed permanent-magnet synchronous machine (HSPMSM) has stricter mechanical restrictions and more intense interactions between multiphysical fields due to high-speed and high-power density characteristics. This article focuses on the thermal effect on mechanical strength and stiffness. As the change of material properties with temperature and the thermal stress caused by thermal expansion properties, this article presents the relationship of the stress and critical speed with two thermal effects obtained by analytical equations and verified by finite-element analysis. The results show that thermal effects could reduce the safety factors of the stress and critical speed, thus increasing the possibility of rotor damage and resonance. To achieve more accurate mechanical, a reasonable machine design is proposed, focusing on the influence of actual uneven thermal distribution. Comparing with a traditional design approach, the new one is more applicable for the HSPMSM design, which considers the assembly method and the operation condition, especially the thermal effects. The fluid-thermal-stress-mode coupling calculation is realized. The experiment has been implemented to verify the validity of this design process. The studies of the thermal effects on mechanical characteristics offer a new idea for designing and debugging practical machines.