Incorporation of sliding mode control into a vibration and noise suppression scheme for a rigid rotor

Abstract

This paper presents a sliding mode control algorithm to suppress the vibration of a rigid rotor supported by magnetic bearings. It is assumed that unbalance exists in the shaft and that the two planes of the shaft motion are coupled by gyroscopic forces. It is assumed that the angular rotation is small in both the normal and transverse directions and that the force and current are related linearly. The sliding mode control law is designed to be robust to rotor unbalance and transient disturbances. A boundary layer is introduced around each sliding hyperplane to eliminate the chattering phenomenon. The results from numerical simulations are presented, which not only corroborate the validity of the proposed controller, but also show the effects of various control parameters as a function of the angular speed of the rotor. Special attention is addressed to the orbital plots of the ends of the rotor. Experimental results are compared to those obtained analytically and demonstrate how the current required by the bearings is affected by the angular velocity of the rotor. [Work sponsored by ONR.]