Robust Control of a Spindle-Magnetic Bearing System Using Sliding-Mode Control and Variable Structure System Disturbance Observer

Abstract

This paper is concerned with the design and control of flexible rotor magnetic bearing systems using the discrete time sliding-mode control method. The plant dynamics, consisting of actuator dynamics and flexible rotor dynamics, are described in detail. A variable structure system (VSS) disturbance observer, with which the state vector and disturbance can be estimated simultaneously, is investigated to compensate the mismatched disturbance load on the rotor. A new discrete time sliding-mode servocontroller that can attenuate the chattering phenomenon is proposed using the VSS observer. The usefulness of the proposed controller is demonstrated through computer simulations and experiments for a spindle-magnetic bearing system under external disturbances and modeling uncertainties.