Active Rotor Controller Design for Vibration and Bend Mitigation Utilizing Active Magnetic Bearings and Internal Shaft Actuation

Strategies are required to reduce vibrations in machines that use rotor systems, as these disturbances reduce the life and quality of the machine. A novel low-frequency on-board counter-bend actuator topology has been designed in order to control high frequency vibrations by taking advantage of synchronous forces from the rotating frame of a rotor supported by Active Magnetic Bearings (AMBs). The AMBs ensure in return stable contact-free levitation of the rotor. A complete model of the rotor system is established, based on a finite element representation of the rotor. The feedback control forces of the AMBs are described to account for the non-collocation of the sensor and actuation, and the PD controller gains are chosen using the sensitivity function. The lowest frequency mode of the operating range is located at 2,700 RPM, and time domain analysis shows that the application of symmetric 80 N.m counter-bend moments on the rotor coupling flanges can reduce the vibration amplitude by 88% at this rotation speed.