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International Journal of Rotating Machinery
Volume 7 (2001), Issue 5, Pages 323-333

Stabilization of Centrifuges with Instabilities Due to Fluid-Structure Interactions: Various Control Approaches

Universität-GH Essen, Lehrstuhl für Mechanik, FB 12, Schfüzenbahn 70, Essen 45127, Germany

Received 30 May 2000; Revised 21 June 2000

Copyright © 2001 Hindawi Publishing Corporation. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Partially filled centrifuges exhibit unstable behavior over particular rotational speed ranges. To remove this unstable behavior, three different control approaches are presented which are experimentally implemented using a magnetic bearing. First, by means of a PD-controller the system stiffness is changed leading to a shift of the instability region. Second, the instability region is removed by a cross coupled feed back of the rotor vibration velocities. This cross coupling directly counteracts the fluid excitation mechanism. Third, a disturbance observer is presented which allows to estimate and compensate the not exactly known fluid force.