ROBUST-CONTROL OF FLEXIBLE ROTOR MAGNETIC BEARING SYSTEMS USING DISCRETE-TIME SLIDING MODE CONTROL

This paper is concerned with the computer-based sliding mode control o f flexible rotor-magnetic bearing systems (FR-MBS). The plant dynamics consisting of actuator dynamics and flexible rotor dynamics are descr ibed. The reduced-order model for controller design is given by elimin ating higher-order modes of the mechanical and electrical magnetic int eraction system. A discrete time sliding mode controller with reduced- order model is proposed and its robust performance is evaluated with s everal simulations based on a calculation model. This digital controll er is implemented to replace a linear analog PID compensator. Levitati on tests using the proposed digital controller are performed and compa red with those of the PID compensator. With a discrete time sliding mo de controller, the running test with high-speed rotation is successful ly increased up to 35 000 rpm without unstable vibration.