A Q-value measurement for damping evaluation of AMB rotors

The sensitivity function of feedback control systems is recommended for AMB (active magnetic bearing) equipped rotors to evaluate the stability margin. Alternatively before rotor operation, we need to predict the resonance severity called Q-value. In this paper, the sensitivity and the Q-value are discussed and the difference is made clear. How to obtain the Q-value from the open loop transfer function is also discussed. Our proposed Q-value function is numerically and experimentally demonstrated so well for several AMB rotors. This obtained Q-value peak agrees with exact values calculated by eigenvalues and/or measured by the half power point method