Strength and Dynamics Analysis of the Novel Composite Rotor in a High-Speed Permanent Magnet Motor

The development of high-speed permanent magnet motors (HSPMMs) has been constrained by the mechanical properties of the rotor. In this article, a hierarchical composite rotor for HSPMM made of composite magnetic materials (CMMs) is proposed. The manufacturing process of CMMs was explained, and the material character was verified by mechanical and magnetic performance experiments. The ultimate tensile strength is much greater than that of traditional permanent magnets (PMs). Due to the special structure of the composite rotor and that the magnetic materials are anisotropic, the analysis is more complex. This article derives the stress analysis equation of composite material rotors under rated operating conditions, and reduces unknown variables and matrix dimensions through rotor structure relationships. This method can increase the convergence and efficiency. Its accuracy is verified by the Finite Element Method (FEM). On the other hand, this article gives the composite rotor dynamics analytical equation including the bearing stiffness, calculates the first two critical speeds, and analyzes the influence of the bearing stiffness and magnetic particle (MP) content on critical speed of the composite rotor. Finally, a prototype was produced and validated through testing.