Robust control of multiple discrete frequency vibration components in rotor - magnetic bearing systems

This paper considers the derivation and application of closed loop vibration controllers that are designed for the attenuation of multiple discrete frequency rotor vibration components. The complex amplitudes of each vibration component are evaluated in real-time and used for dynamic feedback control with frequency matched control signals. Multi-input, multi-output system gain matrices are derived from on-line identification routines, performed under a finite set of different operating conditions. Controller gain matrices are synthesised using linear matrix inequality existence conditions for closed loop system stability and attenuation performance. Thus, the controllers can be designed with a degree of robustness to changing/non-linear dynamics. Implementation and testing is undertaken on a flexible rotor test rig with magnetic bearings. The controllers are shown to simultaneously attenuate vibration due to direct rotor disturbance forces and other indirectly forced non-synchronous frequency components over a range of operating conditions.