Design and analysis of passive homopolar null flux bearings

Electrodynamic Maglev systems (EDSs) and passive magnetic bearings (PMBs) generate magnetic forces by induction through the movement of permanent or superconducting magnets past conducting coils. Nearly all EDSs and PMBs use a null flux coil exposed to changing magnetic fields in the rotation or travel direction. An unusual variant eliminates discrete coils by using field structures that do not vary in the direction of rotation. We discuss the design and analysis of this homopolar variant in this paper. We believe that this is the first combined passive damper/axial support bearing, and we present here the first generalized solution of its governing equations. Actuated brushes during motoring and generating simplify energy exchange when the device is used for flywheel energy storage.