Vibration Control on Active Magnetic Bearing Equipped Flywheel Rotor

Flywheel technology has been developing for an effective and clean means of energy storage techniques. From the point of view of the improvement for the stable rotation during high speed revolution, we employed the active magnetic bearing (AMB) to apply it to a flywheel test rotor. Our AMB equipped flywheel rotor is levitated without mechanical contact by five-axis controllers in the decentralized manner: three positions to vertically suspend this fiat rotor and two X and Y rotations to maintain the rotor at a neutral position. In this paper, we propose several ideas in numerical simulations concerning the AMB control method for the stability improvement of this flywheel rotor. An equivalent reduced model of the rotor is first completed from the quasi-modal method. The traditional PID control is mainly applied to the standstill levitation. This PID controller is not able to cover the stability in the entire speed range, because natural frequencies split into two ways due to the strong gyroscopic effect: the increase of the forward eigenfrequency and the decrease of the backward eigenfrequency. In order to compensate the destabilization caused by this split, we recommend the addition of an optional technique of the cross stiffness control. The simulation proves that the cross stiffness control should be combined with a band-pass filter for selecting the forward eigenmode vibration and a low pass filter for tuning the backward mode vibration. We also consider the spiUover instability due to the flexibility of the flywheel disk.