Innovative Active Magnetic Bearing Design to Reduce Cost and Energy Consumption

Abstract

Abstract An innovative switching-type self-sensing magnetic bearing is presented in this article. The so-called switch-type refers to the operation of each pair of magnetic poles in which, at any time epoch, a sole single pole is energized by feeding electric current while the other is not activated at all. Each pair of poles in the magnetic bearing shares a set of power amplifiers in a switching manner so that the required number of amplifiers can certainly be reduced. In addition, a self-sensing technique is employed by extracting the induced current in the coil wrapped on the pole convex to replace gap sensors that are conventionally used to provide the position deviation measure of the spindle. That is, the cost to equip any position sensor or device can be waived. The proposed magnetic bearing not only reduces the bearing size, but also drastically prevents unnecessary power loss. A self-tuning proportion-derivative controller is synthesized to account for the effects of non linearities of the rotor/bearing system. The proposed switching-type self-sensing control system is verified by intensive experiments to illustrate the validity of the proposed electromagnet design and superiority of the self-tuning proportion-derivative strategy to efficiently stabilize the inherently unstable magnetic suspension system. Keywords: magnetic bearingsswitching controlself-sensing technique Acknowledgment This research was supported by the National Science Council (Taiwan) under grants 97-2221-E-006-182, and the authors express their appreciation.