Digital Controller using a Digital Signal Processor of a Totally Active DC-type Magnetic Bearing System

Abstract

Suspention of a rotor in totally active DC-type magnetic bearings, which is unstable without any control, can be stabilized by feedback control. Existing controllers for the magnetic bearings are composed of analog circuits, because the stabilization requires high-speed-control. But it is difficult for analog controllers to give the magnetic bearings various functions such as force-sensing, rotor-positioning and variable suspention-stiffness as well as contactless suspention, because of the lack of flexibility and adaptability of analog controller.The authors have developed a digital controller for a totally active magnetic bearing system. The controller has two CPU : one is a digital signal processor (DSP) to process the feedback control at high speed for stabilization, and the other is a personal computer to process the flexible and adaptable control. The authors have demonstrated through experiments that the controller enables the magnetic bearing system both to be stable and to have various functions.