An Integrated Active Rotor/Active Magnetic Bearing System

The concept of using internal bend actuation in a rotor supported by active magnetic bearings is proposed. Since the bend occurs within the rotating frame, static bend actuation is equivalent to synchronous excitation from an actuation component based in an inertial frame of reference. This has the advantage that low bandwidth Active Magnetic Bearing (AMB) levitation can be combined with low bandwidth bend actuation for synchronous vibration control. The design of the bend actuator is presented together with the principle of operation. The bend actuation is commanded wirelessly, with low power required to operate lead screw motors from an onboard battery. This is demonstrated experimentally in static tests in which rotor deformation under bend actuation is measured using a laser tracker. Consideration is then given to vibration reduction during rotating tests. The rotor was levitated on AMB's and the synchronous vibration control achievable by static internal bending is demonstrated. The optimal level and orientation of bend actuation was achieved by applying search techniques. These were applied at increments of rotational speed in run-up tests and shown to be particularly effective in compensating for unbalance response at the rotor mid-point.