Sliding Mode Control of a Rigid Rotor via Magnetic Bearings

Abstract

Abstract This paper deals with the sliding mode control of a rigid rotor supported by radial magnetic bearings. First, the control law is developed to be robust to external forces caused by the rotor unbalance and transient disturbances. This control law is then discretized for its implementation on a digital computer. Three methods are presented to determine the required coil current for each magnet. Next, an analytical technique has been developed to calculate the steady state amplitudes of the digital closed-loop system. Lastly, results from this analytical technique and numerical simulations are presented for the rotor operating at 30,000 rpm.