Mot. Cole et al., VIBRATION CONTROL OF A FLEXIBLE ROTOR MAGNETIC BEARING SYSTEM SUBJECTTO DIRECT FORCING AND BASE MOTION DISTURBANCES, Proceedings of the Institution of Mechanical Engineers. Part C, Journal of mechanical engineering science, 212(7), 1998, pp. 535-546
During operation, a rotor/magnetic bearing system may be subject to va
rious sources of vibration, either directly applied to the rotor or tr
ansmitted through the bearings owing to base motion. This paper consid
ers controller designs that are capable of attenuating vibration arisi
ng from either source. It advances the current state of research in th
e area since other controller designs have considered only the direct
forcing case. If base motion is not considered in the design of the co
ntroller then this disturbance may cause the bearing clearance limits
to be reached. Controller design is formulated as an H-infinity optimi
zation problem, with mixed design objectives. A new controller is deri
ved that can simultaneously reduce vibration and minimize the effect o
f base motion on relative rotor to bearing displacement. Account is ta
ken of the fact that the bearings can apply only limited control force
. The design study was complemented by a programme of experimental wor
k. The base of a rig was subjected to impulse inputs and the results s
how the effectiveness of the new controller design. It is demonstrated
that proportional, integral and derivative (PID) controllers, or cont
rollers designed for unbalance vibration attenuation only, may result
in rotor contact with retainer bushes, while the new controller may pr
event contact. The potential now exists for continuing safe operation
of flexible rotor/magnetic bearing systems such as compressors, gas tu
rbines, generators, etc., in transport applications, during seismic ev
ents or in environments with expected base input disturbances.