Practical applications of singular value decomposition in rotordynamics

Cloud, C. Hunter; Li, G; Maslen, Eric H.; Barrett, Lloyd; Foiles, William C.

doi:10.1080/14484846.2005.11464477

Cited by 10 publications

(14 citation statements)

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“…Maximum singular values are a convenient tool to assess the possibility of excessive vibrations in rotordynamic analyses [12]. If the input and output are normalized with respect to their bounds, we only need to check the condition of (15).…”

Section: Resultsmentioning

confidence: 99%

“…In contrast, simulations with parameter variations can be conveniently done in frequency-domain. Furthermore, the use of singular values for rotordynamic analyses [12] facilitates the controller comparison.…”

Section: Simulation Modelmentioning

confidence: 99%

“…where Ω is the running speed, is the unbalance, and w is a unit vector. The closed-loop transfer function from disturbance w to the performance measure z is then obtained from z = C sys ( I − A sys ) −1 B sys W w = G cl ( ; Ω) W w. (12) If the performance measure is normalized by an output weighting matrix W , then we can write…”

Section: System Modelmentioning

confidence: 99%

“…The singular value decomposition is a useful tool for rotordynamic analyses, since it can tell us the worst case [12]. If the signals are normalized as in (13), the condition that…”

Section: System Modelmentioning

confidence: 99%

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An Appraisal of Power-Minimizing Control Algorithms for Active Magnetic Bearings

Yoo

Noh

2015

Shock and Vibration

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Active magnetic bearings consume much less power than conventional passive bearings, especially when power-minimizing controllers are employed. Several power-minimizing controllers have been proposed, such as variable bias controllers and switching controllers. In this paper, we present an appraisal of the power-minimizing control algorithms for active magnetic bearings in an attempt to provide an objective guideline on the merits of the control algorithms. In order for the appraisal, we develop an unified and consistent model of active magnetic bearing systems. The performances of the power-minimizing controllers are assessed through this model. The results show that the power-minimizing controllers indeed save considerable power when the machine state is relatively steady. However, a simple proportional-derivative type controller is on a par with the much more complex powerminimizing controllers in terms of power consumption when the machine is experiencing transient loads.

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Section: Resultsmentioning

confidence: 99%

Section: Simulation Modelmentioning

confidence: 99%

Section: System Modelmentioning

confidence: 99%

“…The singular value decomposition is a useful tool for rotordynamic analyses, since it can tell us the worst case [12]. If the signals are normalized as in (13), the condition that…”

Section: System Modelmentioning

confidence: 99%

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An Appraisal of Power-Minimizing Control Algorithms for Active Magnetic Bearings

Yoo

Noh

2015

Shock and Vibration

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“…Singular Value Decomposition (SVD) can be used as a worst case measure, since the actual distribution of mass unbalance is unknown in terms of magnitude and phase. This can be applied for control synthesis shown in (Schweitzer et al, 2009) as well as for analysis shown in (Cloud et al, 2005) and with application to a subsea compressor with a flexible rotor (Maslen et al, 2012).…”

Section: Introductionmentioning

confidence: 99%

Design of robust AMB controllers for rotors subjected to varying and uncertain seal forces

Lauridsen

Santos

2017

Mechanical Engineering Journal

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This paper demonstrates the design and simulation results of model based controllers for AMB systems, subjected to uncertain and changing dynamic seal forces. Specifically, a turbocharger with a hole-pattern seal mounted across the balance piston is considered. The dynamic forces of the seal, which are dependent on the operational conditions, have a significant effect on the overall system dynamics. Furthermore, these forces are considered uncertain. The nominal and the uncertainty representation of the seal model are established using results from conventional modelling approaches, i.e. Computational Fluid Dynamics (CFD) and Bulkflow, and experimental results. Three controllers are synthesized: I) An H ∞ controller based on nominal plant representation, II) A µ controller, designed to be robust against uncertainties in the dynamic seal model and III) a Linear Parameter Varying (LPV) controller, designed to provide a unified performance over a large operational speed range using the operational speed as the scheduling parameter. Significant performance improvement is shown for robust control, incorporating model uncertainty, compared to nominal model based control.

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Contact dynamic phenomena in rotating machines: Active/passive considerations

Keogh

2012

Mechanical Systems and Signal Processing

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There are machine operating regimes in which rotor/stator interactions may lead to problematic rotor dynamic behaviour. For example, dynamic heat sources arising from seals, bearings and other rubbing stator components may cause rotor thermal bend instability. In active magnetic bearing (AMB) systems, the rotor may experience forward and backward whirl rubs with touchdown bearings (TDBs). In abnormal cases, rotor transient and bounce interactions with such bearings may involve highly localized and short duration contacts. This paper discusses certain contact phenomena that may occur in passive and active systems. For example, the rub induced spiral behaviour arises from a combination of unbalance and a thermal input that moves slowly around the rotor, typically in passive rotorbearing systems. However, the instability can be regarded as if arising from a closed loop feedback system. Hence it is possible to analyse the phenomenon using techniques that have been developed for active control systems. Rotors levitated by AMBs are truly active, but there are fundamental issues that may arise when contact with TDBs occurs. AMB control and contact interactions are discussed together with the benefits for making the TDB an active element. The reason for this lies in the potential ability to control the contact dynamics and associated mechanical and thermal stresses. A prototype system is described.

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Practical applications of singular value decomposition in rotordynamics

Cited by 10 publications

References 0 publications

An Appraisal of Power-Minimizing Control Algorithms for Active Magnetic Bearings

An Appraisal of Power-Minimizing Control Algorithms for Active Magnetic Bearings

Design of robust AMB controllers for rotors subjected to varying and uncertain seal forces

Contact dynamic phenomena in rotating machines: Active/passive considerations

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