Stabilizing Synchronization Control of Rotor-Magnetic Bearing Systems

Abstract Active magnetic bearings, which provide non-contact suspension for high-speed rotors, have received increasing attention in recent years. Although the contactless nature of magnetic bearings brings up many advantages over conventional bearings, one of the challenging problems is to stabilize the rotor of the magnetic bearing systems that is very sensitive to outside disturbances and plant uncertainties. In this paper, a stabilizing synchronization design of rotor-magnetic bearing systems is proposed by incorporating cross-coupling technology into the optimal control architecture, which can be decomposed into two problems: a robust optimal control problem to improve the synchronization performance of the rotor in the radial directions and a stability problem. The control scheme is based on minimization of a new quadratic performance index in which the synchronization errors are embedded. Stability of the control scheme is also investigated through the linear quadratic Gaussian (LQG) optimal control technique. Simulations on a compact and efficient flywheel energy storage system with integrated magnetic bearings demonstrate that the proposed approach is very effective to recover the unstable system when the outside disturbances are present.