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M. Hirschmanner, H. Springer:
"Adaptive Vibration and Unbalance Control of a Rotor Supported by Active Magnetic Bearings";
Talk: Eighth International Symposium on Magnetic Bearings, Mito, Japan; 2002-08-26 - 2002-08-28; in: "Proceedings of The Eighth International Symposium on Magnetic Bearings (ISMB-8)", (2002), 483 - 488.

The system under investigation in this paper is a rigid rotor supported by active magnetic bearings (AMB). Two coexisting sources of vibrations which are simultaneously exciting the rotor are considered. First, mass unbalance excitation as a synchronous periodic disturbance and second, destabilizing cross coupling forces. It is shown that any distribution of cross coupling forces along the rotor can be represented by a skew symmetric stiffness matrix with three independent parameters. These parameters may change with time as they depend, for example, on the fluid or gas pressure in the machine and other machine operating conditions.
The basic AMB-control is carried out by a simple PID controller while for the compensation of both excitation mechanisms two independent control algorithms are used. In order to compensate the destabilizing cross coupling forces a standard least square estimator along with a time varying so-called forgetting factor estimates the unknown parameters of the cross coupling mechanism. The mass unbalance forces are compensated by a recursive gain scheduled algorithm which needs no a priori knowledge neither of the amount nor the direction of the mass unbalance. By combining these two algorithms a significant reduction of the vibration level is achieved. The behavior of both algorithms and their interaction with each other is studied by numerical simulation.