Simulation-Based Controller Design for an Active Auxiliary Bearing

Abstract

A framework for the development of a feedback controller for an active auxiliary bearing is presented. In a new approach, a dry bushing type auxiliary bearing is attached to the foundation via two unidirectional actuators. The control force is applied indirectly using the active auxiliary bearing only in case of rubbing. A simulation for the elastic rotor and the auxiliary bearing including the non-smooth nonlinear dynamics of the rubbing contact is used to develop the feedback controller. A robust two-phase control strategy has been developed which stabilizes the rotor system in case of rubbing and effectively avoids "backward whirling". Experimental studies have been carried out at a rotor test rig. The experiments show the outstanding success of the strategy. In case of rubbing, the contact forces are reduced up to 85%.

Impulsive Control of the Rotor-Stator Rub Based on Phase Characteristic

“…Chavez et al [5] used sliding control and cross-coupled feedback in a rotor system to reduce the impact forces and to decrease the lateral and torsional vibrations. Ginzinger and Ulbrich [6] developed a two-phase control strategy to stabilize the rotor system in case of rub and effectively avoid backward whirling. References [7,8] considered the concept of using an active auxiliary bearing operating with an active magnetic bearing system.…”

A Method to Transit the Rotor-to-Stator Rubbing to Normal Motion Using the Phase Characteristic

“…Chavez et al [14] used sliding control and cross coupled feedback in a rotor system driven by a power limited motor to reduce the impact forces and to decrease the lateral and torsional vibrations. Ginzinger and Ulbrich [15] presented a framework for the development of a feedback controller for an active auxiliary bearing. Cade et al [16] considered an active auxiliary bearing system with a control strategy designed to limit the trapped contact modes in a rotor/magnetic bearing system.…”

“…Cade et al [16] considered an active auxiliary bearing system with a control strategy designed to limit the trapped contact modes in a rotor/magnetic bearing system. Because the auxiliary bearing exerts control forces on the rotating system only when rotor establishes contact with the auxiliary bearing, [13][14][15][16] dealt with the problem of rotor-to-stator rubbing mainly by minimizing contact force or bringing system into a stable full annular rub.…”