Active Control of Rotating Machinery Under Rotor-Stator Contact Conditions

Patrick S. Keogh, Chris Lusty, Nicola Y. Bailey, Fawaz Saket

Research output: Chapter or section in a book/report/conference proceedingChapter or section

3 Citations (SciVal)


A rotor spinning within an active magnetic bearing (AMB) system will normally be levitated and hence operate without rotor-stator contact. External disturbances and inherent unbalance may be compensated with appropriate control to keep rotor deviations within the clearance gap. However, AMBs have limited dynamic load capacity due to magnetic material field saturation. Hence overload conditions may result in rotor-stator contact. A touchdown bearing (TDB) and rotor landing sleeve are usually included to protect the expensive rotor, magnetic bearing and sensor components from damage. Once rotor-TDB contact has been made, rotor dynamic conditions may ensue resulting in persistent rotor bouncing or rubbing limit cycle responses. Prolonged exposure to these severe dynamics will cause TDB degradation and require regular replacement. If possible, a clear aim should be to restore contact-free levitation through available control capability in an efficient manner. This paper is used to guide the control options that are available to restore contact-free levitation. The use of AMB control is appropriate if the required control forces are within saturation limits. It is also possible to actuate TDBs and destabilize persistent rotor dynamic contact conditions. For example, piezo-based actuation offers larger control forces than those from magnetic bearing systems. Hybrid control action involving both types of actuation system has the greatest potential for completely robust restoration of contact-free levitation.

Original languageEnglish
Title of host publicationProceedings of the 10th International Conference on Rotor Dynamics - IFToMM
EditorsK. Calvaca, H. Weber
Place of PublicationCham, Switzerland
Number of pages11
ISBN (Print)9783319992709
Publication statusE-pub ahead of print - 19 Aug 2019
Event10th IFToMM International Conference on Rotordynamics - Windsor Barra Convention Center, Rio de Janeiro , Brazil
Duration: 24 Sept 201827 Sept 2018

Publication series

NameMechanisms and Machine Science


Conference10th IFToMM International Conference on Rotordynamics
CityRio de Janeiro


  • Contact-free levitation
  • Magnetic bearings
  • Touchdown bearings

ASJC Scopus subject areas

  • Mechanics of Materials
  • Mechanical Engineering


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