Hybrid Adaptive Rotor Imbalance Vibration Control via Passive Autobalancer and Active Bearing Actuation

Many researchers have explored the use of active bearings, such as non-contact Active Magnetic Bearings for example, to control imbalance vibration in rotor systems. This paper develops a new hybrid adaptive imbalance vibration control approach based on an active bearing augmented with a passive automatic balancing device (ABD) to enhance the balancing and vibration isolation capabilities. Essentially, an ABD or “autobalance” consists of several freely moving eccentric balancing masses mounted on the rotor, which, at supercritical operating speeds, act to cancel the rotor’s imbalance at steady-state. This “automatic balancing” phenomena occurs as a result of nonlinear dynamic interactions between the balancer and rotor wherein the balancer masses naturally synchronize with the rotor with appropriate phase to cancel the imbalance. Since the ABD acts directly on the rotor in the rotating frame, rotor whirl amplitudes are passively reduced without any forces transmitted between rotor and bearing. Therefore, this hybrid ABD/active bearing approach enables increased rotor balancing capability and reduced steady-state control power consumption. However, due to the inherent nonlinearity of the autobalancer, the potential for other, non-synchronous limit-cycle behavior exists. In such situations, the balancer masses do not reach their desired synchronous balanced steady-state equilibrium positions resulting in increased rotor vibration. To address this, a new adaptive active control algorithm for the rotor/bearing/ABD system is derived based on the Lyapunov approach which guarantees global asymptotic stability of the synchronous balanced condition. This approach enables the controller to cope with both the system nonlinearity introduced by the passive ABD and with the rotor imbalance uncertainty. Here, the controllability of system is established through an accessible distribution Lie bracket operational analysis. The simulation results demonstrate the advantages of the hybrid ABD/active bearing system. In particular, it is shown that the balanced equilibrium can be made globally attractive under the action of the adaptive bearing control law, and that the steady-state power levels are significantly reduced via the addition of the ABD. These findings are relevant to limited power applications such as in satellite reaction wheels or flywheel energy storage batteries.