Optimization of damping compensation for a flexible rotor system with active magnetic bearing considering gyroscopic effect

Active magnetic bearing (AMB) levitated rotating machineries are always required to operate above the rotor first bending critical speed to achieve a high power density. It is important to ensure safe rotor run-down through critical speeds. This paper presents an optimization of damping compensation for a flexible rotor to make maximal use of the limited electromagnetic force to retain flexible deformation. The design, rotor modal properties, and bending model test for an AMB test rig which typifies a 10-kW centrifugal compressor are described in detail. The optimal compensation phase angle with and without considering the gyroscopic effect is first derived from a theoretical model. The flexible deformations with the different control radius and phase are also analyzed. Then, the phase angle from flexible deformation to electromagnetic force in the existing control system is experimentally identified. A phase-shift filter is designed to compensate the corresponding phase difference around the bending frequency. The damping compensation experiments validate the proposed optimization approach.