Active Vibration Control of a Flexible Rotor by Flexibly Mounted Internal-Stator Magnetic Actuators

This paper demonstrates vibration reduction in a hollow rotating shaft by means of internal-stator active magnetic actuators, which are resiliently mounted. This problem requires further consideration over and above classic rotor/magnetic bearing systems on account of the flexible behavior of the magnetic actuator support structure. This paper presents an experimental facility conforming to the proposed topology, with a particular focus on the control problem such a system presents. The unique challenges are discussed, and a solution is presented in the form of H _\infty-based control. Ultimately, experimental results demonstrate the system to be capable of substantial rotor vibration suppression, including while passing the rotor's first critical speed, which was not obtainable with simpler classical control techniques. This means the top achievable rotor speed was increased from approximately 3000 r/min without magnetic actuator vibration suppression to over 9000 r/min with vibration suppression active. At the rotor critical speed, the magnetic actuators affect a reduction in rotor vibration amplitude of over 70% compared to the rotor supported purely on mechanical bearings, while simultaneously avoiding excessive excitation of the flexible active magnetic actuator support structure.