Development of a radial active magnetic bearing for high speed turbo-machinery motors

Abstract

A radial active magnetic bearing system for a high speed turbo-machinery induction motor is presented. In this application, a massive rotor is required in order to make up high power and speed. So radial active magnet bearing should be designed to support this rotor mass. Precise analysis of a radial active magnetic bearing is presented from the point of view of electromagnets design. From the controller design point of view, the radial active magnetic bearing can be thought as a combination of two independent magnetic suspensions, each of which is made up of a differential magnetic actuator. Magnetic suspension system is open-loop unstable. So some control techniques like feedback stabilization with proportional-derivative (PD) controls are required in order to make the closed-loop system stable. In practical applications like high speed rotating machine, the proportional-derivative (PD) controls are compensated by 2n derivative control which reshapes the high-frequency end of the stiffness and damping of the system. In magnetic suspension system, massive rotor can act like static disturbance, which makes the center of the rotor out of the center of rotation. So an integral control algorithm is also required. Finally for the developed active radial bearing in turbo-machinery motor, the proportional-derivative-2n derivative-integral (PIDD) control algorithms are implemented with real-time simulator, and the test results are presented