Identification of speed-dependent active magnetic bearings dynamic parameters in aflexible rotor system

Active magnetic bearings (AMBs) support rotors using electromagnetic force rather than mechanical force. It is necessary to accurately identify AMBs force coefficients (equivalent stiffness and damping) since they play a key role in the rotordynamic analysis. The identification is usually performed by analyzing the unbalance response; however, the unknown residual unbalances will decrease the identification accuracy and rigid rotor model is only available when the rotating speed is far below the bending critical speed. To address the above issues, this paper proposes an identification algorithm to estimate the stiffness and damping parameters of a flexible rotor AMBs system using two independent unbalance response data. The proposed algorithm is employed for experimental identification for a flexible rotor AMBs system ranging from 3,000 rpm (50 Hz) to 30,000 rpm (500 Hz).