Analytical Model of Rotor Maximum Mechanical Stress for Interior Permanent Magnet Synchronous Motors Considering Thermal Effects

Now, interior permanent magnet synchronous motors (IPMSMs) are developing rapidly toward higher power density and wider speed range. In this process, it is particularly critical to quickly and accurately estimate the rotor mechanical strength for the IPMSM in the limit state. For this purpose, in this article, an analytical model of the maximum mechanical stress in the rotor for the IPMSM considering thermal effects is investigated. First, the temperature calculation model is innovatively developed based on the improved thermal domain method. Thus, the accurate acquisition of the temperature variation function on each component is accomplished. In the next step, the center-of-mass equivalent circular method is introduced to subdivide the solution domain for the complicated hybrid magnetic circuit structure. After that, on this basis, the forces on each equivalent solution domain are analyzed by considering the effect of thermal stresses while combining with the thick-walled cylinder theory. The general solution of the stress-displacement function on each equivalent solution domain is obtained. Furthermore, the boundary condition between the neighboring equivalent solution domains is established and solved. In this way, the rapid construction and accurate solution of the analytical model of the maximum mechanical stress in the rotor considering thermal effects is completed. Consequently, the fast and accurate estimation of the maximum mechanical stress in the rotor of the IPMSM considering thermal effects is well achieved. Finally, the validity and engineering practicality of this study are verified by simulation and experiment.