Single Plane Radial, Magnetic Bearings Biased With Poles Containing Permanent Magnets

Abstract

Magnetic bearings biased with permanent magnets have lower coil resistance power losses, and the magnets can also be used to help support a constant side load. In this paper, the performance of a single plane radial magnetic bearing biased with permanent magnets in several poles is presented. Although it has less load capacity and stiffness than a similarly sized electrically biased single plane heteropolar bearing, it does not require bias current, and its ratio of load capacity to coil resistance power loss is significantly better. This type of permanent magnet bearing has only a single plane of poles. It can be distinguished from the homopolar bearing type which has two planes and which can also be biased with permanent magnets. Magnetic circuit models for the novel single plane bearing are presented along with verification by finite element models. Equations for the key performance parameters of load capacity, stiffness, coil inductance and resistive power loss are also presented.