Shock-induced persistent contact and synchronous re-levitation control in an AMB-rotor system

Yixin Su, Yongpeng Gu, Patrick Keogh, Suyuan Yu, Gexue Ren

Research output: Contribution to journalArticlepeer-review

Abstract

Active magnetic bearings (AMBs) have limited dynamic load capacity due to magnetic saturation. Hence, large external disturbances (such as shock loads) may cause contact between the rotor and touchdown bearings (TDBs), which may evolve into complex dynamic behaviour and damage the machine. This paper considers the shock responses of a rotor and viable re-levitation control options when the AMB is still functional. Bi-stable responses and shock-induced persistent forward rubbing were observed in an experimental AMB-flexible rotor facility and its numerical model. The analytical solution for steady synchronous motions with rubbing of a general AMB-flexible rotor system was proposed. The standard control action for a contact-free rotor state would not be appropriate due to phase changes and the displacement amplitude differences in the frequency responses. To destabilise the persistent contact responses and restore contact-free levitation, open-loop phase search based synchronous compensation (PSSC) control and synchronous motion compensation (SMC) control are designed, which are activated when a persistent contact is detected. Stability of the control system and the effectiveness of these two re-levitation control methods are verified by simulation and experimental results. It is also found by comparison that the efficiency of PSSC depends on the phase difference (incorrect phases may degrade rotor response), while the SMC consumes more computing effort.

Original languageEnglish
Article number108174
Number of pages22
JournalMechanical Systems and Signal Processing
Volume163
Early online date7 Jul 2021
DOIs
Publication statusE-pub ahead of print - 7 Jul 2021

Keywords

  • Active magnetic bearing
  • Bi-stable phenomenon
  • Phase search
  • Re-levitation control
  • Shock response

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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