Finite Element Analysis on Magnetic and Mechanical Characteristics for Hybrid Magnetic Bearing

Abstract

The configuration and working principle of a novel radial hybrid magnetic bearing (RHMB) are introduced in this paper, and its 3-D nonlinear finite element model, based on which air gap magnetic field distributions and magnetic forces on the rotor under different displacements and control currents are calculated, is established with the software ANSYS. The magnetic forces calculated by finite element method (FEM) are compared with those calculated by equivalent magnetic circuit method. The results show that the FEM can comprehensively reflect the magnetic field distribution and mechanical characteristics for the RHMB. When the rotor is in a suspension state without a static load or external disturbance, the air gap magnetic field is uniform and continuous, which is advantageous in reducing eddy current loss. The fluxes of the two radial channels are decoupled from each other, which is favor of reducing control power loss and simplifying control algorithm of the system. The radial magnetic force is approximately linear with respect to radial displacement and control current under the premise that soft magnetic material is not saturated, which is advantageous in improving system control precision. The thrust bearings in conventional structures could be excluded because of the axial passive resilience and large passive stiffness in the novel RHMB, which makes the system a low power loss and a simple structure.