Measurement and calibration of rotor/touchdown bearing contact in active magnetic bearing systems

Fawaz Saket, Mehmet Sahinkaya, Patrick Keogh

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13 Citations (SciVal)
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Active magnetic bearing systems provide contact-free rotor levitation, which allows near frictionless rotation and high rotational speeds when they operate normally. Under certain operational conditions, a transient fault, overload condition, or disturbance may occur. Touchdown bearings or bushings are therefore implemented in such systems to prevent contact between rotor and stator laminations. If the rotor makes contact with a touchdown bearing, the rotor dynamics may become transient or persistent in contact. Appropriate control strategies through the magnetic bearings to restore contact-free rotor operation may extend the life of touchdown bearings, and minimise operational downtime. To achieve this, an understanding of the contact dynamics is required, together with the relationship between contact and magnetic bearing forces. In this paper, rotor/touchdown bearing contact conditions are investigated experimentally using an active magnetic bearing system with a flexible rotor. Design methodology is presented for a measurement system capable of providing rotor/touchdown bearing contact related data, based on strain measurement. Strain induced contact signals are calibrated against applied magnetic bearing forces. The frequency dependent behaviour of the active magnetic bearing system is considered using evaluated force and phase measurements. The measurement data represent system identification for the potential of active magnetic bearing force-based contact control.
Original languageEnglish
Article numberMSSP17-1633
Pages (from-to)1-18
Number of pages18
JournalMechanical Systems and Signal Processing
Early online date20 Dec 2018
Publication statusPublished - 1 May 2019


  • Active magnetic bearing
  • Contact rotor dynamics
  • Rotor touchdown contact
  • Strain measurement
  • Touchdown bearing

ASJC Scopus subject areas

  • Control and Systems Engineering
  • Signal Processing
  • Civil and Structural Engineering
  • Aerospace Engineering
  • Mechanical Engineering
  • Computer Science Applications


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