Analysis and Evaluation of Unbalance Resonance Vibration and Bearing Reaction Force for Active Magnetic Bearing Equipped Flexible Rotor

Flexible Rotors supported by active magnetic bearing (AMB) must pass through critical speeds of two rigid modes and several bending modes. The AMB equipped rotor requires control means to achieve low unbalance vibrations with the low driving current during the spin-up operation and the rated rotation. For this requirement, an unbalance vibration analysis program is developed including calculation of the resultant bearing reaction force. By the use of this developed program, the optimum control technique is evaluated for flexible rotors supported by AMBs, regarding the fol1owing four means: PID, Ncross, Ncut + Ncross, Feed Forward (FF) Excitation. In addition to the numerical evaluation, a rotation test is performed to determine experimenta11y the best strategy for the AMB control. The obtained numerical evaluation is accepted by the experimental results gained from the rotation test. It is concluded numerica11y and experimenta11y that the technique of FF excitation is the best one among the four above methods with respect of low resonance amplitude and low control current to pass the first bending critical speed.