Methods and apparatus for closed-loop control of magnetic bearings

摘要

A magnetic bearing control system for a rotating shaft, for example, includes a plurality of electromagnets disposed around and in close proximity to the surface of the shaft. The control system provides a bias current to the electromagnets to maintain the shaft in a null position. Levitation of the shaft is controlled by a levitation controller, and disturbance rejection is effected by a disturbance rejection controller. Flux sensors, suitably located near the electromagnets, determine the magnitude and polarity of the flux resident in the gap between each electromagnet and the shaft. The controller determines the size of the gap based on the flux and generates a corresponding control signal to maintain the position of the shaft within the bearing.