Analysis of rotor strength for surface-inserted high-speed permanent magnet motors

Surface-inserted high-speed permanent magnet motors (SHPMM) find extensive application in high-speed and ultra-high-speed motors as permanent magnets are fixed easily and have small assembling stress and high overload capability. However, because of the complex rotor structure, there is still a lack of analytical solutions for rotor strength. In this paper, the rotor of an SHPMM was divided into four parts: sleeve, permanent magnets, convex plates, and cylindrical core. According to the elasticity theory, an analytical solution of the rotor stress intensity of the SHPMM was derived by using the polar coordinates. Subsequently, the effective feasibility of the scheme designed proposed in the paper is verified by performing simulations in finite elements. On this basis, the four-dimensional visualization algorithm was employed to examine the influences of the parameters in the scheme design on the strength of the rotor, which incorporates the amount of interference, sleeve thickness, and rotational speed. It follows that the analytical method mentioned in this paper demonstrates precise calculations of stresses in the rotor of the SHPMM. The stresses in the permanent magnets exhibit a notable increase with the growth of interference and sleeve thickness whereas they gradually decrease with an increase of rotational speed.