Analysis of Magnetic Systems of Magnetic Bearings Biased with Permanent Magnets

摘要

Interacting magnetic systems are analyzed for active magnetic radial bearings that are combined with permanent magnets to provide bias force and electromagnets to supply control force. The permanent magnets are placed between two stators, and share their pole legs with those of the electromagnets. A simplified magnetic circuit model is proposed for the magnetic systems using a linear demagnetization curve for the characteristics of a permanent magnet. Linearized dynamical equations of incremental magnetic fluxes are presented with the assumption that magnet coils have no bias current in the horizontal direction. To check the validity of the analysis, experimental results with a fixed working airgap are compared with the numerical results using identified parameters of the model.