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

The development of high-speed permanent magnet motors has been constrained by the mechanical properties of the rotor. In this paper, it is proposed a hierarchical composite rotor for high-speed permanent magnet motor made of composite magnetic materials. It was explained the manufacturing process of composite magnetic materials, and verified its material performance through mechanical and magnetic performance experiments. The ultimate tensile strength is much greater than that of traditional permanent magnets. Due to the special structure of the composite rotor and the magnetic materials are anisotropic, the analysis is more complex. This paper derives the stress analysis equation of composite material rotors under rated operating conditions, reduces unknown variables and matrix dimensions through rotor structure relationships. This method can increase the convergence and efficiency. And it is verified by FEM. On the other hand, this paper 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 content on critical speed of the composite rotor. Finally, a prototype was produced and validated through testing.