TU Darmstadt / ULB / TUbiblio

Stability improvement of a flexible rotor in active magnetic bearings by time-periodic stiffness variation

Dohnal, Fadi and Markert, Richard :
Stability improvement of a flexible rotor in active magnetic bearings by time-periodic stiffness variation.
In: 10th International Conference on Motion and Vibration Control (MOVIC 2010), 17.-20. Aug. 2010, Tokyo, Japan. Proceedings of MOVIC 2010 Tokyo, Japan
[Conference or Workshop Item] , (2010)

This is the latest version of this item.

Abstract

Previous theoretical studies have shown analytically and numerically that a vibrating system can be stabilised and its vibrations can be suppressed by an open-loop control of a stiffness parameter, a stabilisation by parametric stiffness excitation. In this paper this approach is investigated further numerically, analytically and experimentally for a flexible rotor with multiple disks supported by active bearings. A periodic, open-loop control of the stiffness coefficients of a bearing is realised by periodically changing the control parameters of an active magnetic bearing. This periodic variation of control parameters is regulated at fixed frequency and amplitude in such a way that it acts like a parametric excitation on the rotor system. As it was shown for simple vibrating structures (chain mass system, cantilever, Jeffcot rotor), the periodic variation may lead to an effective vibration reduction in a complex rotor system. Since this control is open-loop, it can operate in parallel to existing and well-established controllers already used in active magnetic bearings. In this paper, the method of damping by parametric excitation is realised for the first time experimentally in a rotor system. Both direct numerical simulations and analytical predictions are performed to calculate ranges for control and system parameters where damping by parametric excitation is effective. Results frombothmethods are compared with first experimental results. Finally, analytical conditions are given under which the damping by parametric stiffness is effective and the damping effect is guaranteed.

Item Type: Conference or Workshop Item
Erschienen: 2010
Creators: Dohnal, Fadi and Markert, Richard
Title: Stability improvement of a flexible rotor in active magnetic bearings by time-periodic stiffness variation
Language: English
Abstract:

Previous theoretical studies have shown analytically and numerically that a vibrating system can be stabilised and its vibrations can be suppressed by an open-loop control of a stiffness parameter, a stabilisation by parametric stiffness excitation. In this paper this approach is investigated further numerically, analytically and experimentally for a flexible rotor with multiple disks supported by active bearings. A periodic, open-loop control of the stiffness coefficients of a bearing is realised by periodically changing the control parameters of an active magnetic bearing. This periodic variation of control parameters is regulated at fixed frequency and amplitude in such a way that it acts like a parametric excitation on the rotor system. As it was shown for simple vibrating structures (chain mass system, cantilever, Jeffcot rotor), the periodic variation may lead to an effective vibration reduction in a complex rotor system. Since this control is open-loop, it can operate in parallel to existing and well-established controllers already used in active magnetic bearings. In this paper, the method of damping by parametric excitation is realised for the first time experimentally in a rotor system. Both direct numerical simulations and analytical predictions are performed to calculate ranges for control and system parameters where damping by parametric excitation is effective. Results frombothmethods are compared with first experimental results. Finally, analytical conditions are given under which the damping by parametric stiffness is effective and the damping effect is guaranteed.

Title of Book: Proceedings of MOVIC 2010
Volume: 10-203
Place of Publication: Tokyo, Japan
Collation: 11 S.
Uncontrolled Keywords: flexible rotor, active magnetic bearings, parametric excitation
Divisions: 16 Department of Mechanical Engineering > Institute of Applied Dynamics (AD)
16 Department of Mechanical Engineering
Event Title: 10th International Conference on Motion and Vibration Control (MOVIC 2010)
Event Location: Tokyo, Japan
Event Dates: 17.-20. Aug. 2010
Date Deposited: 23 Mar 2011 14:58
Export:

Available Versions of this Item

  • Stability improvement of a flexible rotor in active magnetic bearings by time-periodic stiffness variation. (deposited 23 Mar 2011 14:58) [Currently Displayed]

Optionen (nur für Redakteure)

View Item View Item