Transient Response of Active Magnetic Bearing Rotor During Rotor Drop on Backup Bearings

2006 ◽  
Vol 220 (6) ◽  
pp. 785-794 ◽  
Author(s):  
S Zeng ◽  
J-Q Zhang ◽  
H-N Wang
Keyword(s):  
Numerical Analysis ◽  
Dynamic Behaviour ◽  
Magnetic Bearing ◽  
Rotating Machinery ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Transient Behaviour ◽  
Whirling Motion ◽  
Full Speed ◽  
Rotor Journal

Backup bearing is a key safety component of the rotating machinery with the active magnetic bearings (AMBs). Owing to many unexpected reasons, the AMB rotor running at the full speed may drop onto the backup bearings. Sometimes, the full clearance whirling motion is induced, which is harmful to the machine. Therefore, it is quite important to know the transient behaviour of the AMB rotor and the backup bearing. Till date, a lot of works have been performed on the AMB rotor drop and various mathematical models were established. However, most of them took into account only the interaction between the rotor journal and the backup bearing but neglected the interaction between the shaft and the stator component. As we know, for a real AMB machinery, there should be seal components, and the clearance of the seal component is very small to avoid the leakage. If an AMB failure occurs, the interaction between the shaft and the seal component is likely to happen. Thus, it is more reasonable to include this factor into the AMB rotor drop model. The problem is addressed in this work. The previous model is extended to include the shaft-stator contact. The numerical analysis based on two sets of AMB rotor data shows that the dynamic behaviour of the AMB changes greatly, if the shaft-stator contact is considered. There is no longer an optimum support damping to prevent the harmful full clearance whirling motion, and at this time, a well-balanced AMB rotor is preferred.

Dynamic Analysis of Rotor System With Misaligned Retainer Bearings

2008 ◽  
Vol 130 (2) ◽  
Author(s):  
Antti Kärkkäinen ◽  
Marlene Helfert ◽  
Beat Aeschlimann ◽  
Aki Mikkola
Keyword(s):  
Simulation Model ◽  
Ball Bearing ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
System Failure ◽  
Active Magnetic Bearings ◽  
The Finite Element Method ◽  
Whirling Motion ◽  
The Magnetic Field

Active magnetic bearings present a technology that has many advantages compared to traditional bearing concepts. Active magnetic bearings, however, require retainer bearings in order to prevent damages in the event of a component, power, or a control system failure. In the drop-down, when the rotor drops from the magnetic field on the retainer bearings, the design of the retainer bearings has a significant influence on the dynamic behavior of the rotor. In this study, the dynamics of an active magnetic bearing supported rotor during the drop on retainer bearings is studied employing a simulation model. The retainer bearings are modeled using a detailed ball bearing model while the flexibility of the rotor is described using the finite element method with component mode synthesis. The model is verified by comparing measurements carried out using an existing test rig and simulation results. In this study, the verified simulation model is employed studying the effect of misalignment of retainer bearings during the rotor drop-down on the retainer bearings. It is concluded in this study that the misalignment of the retainer bearings is harmful and can lead to whirling motion of the rotor.

Safety and Reliability Aspects for Active Magnetic Bearing Applications - A Survey

2005 ◽  
Vol 219 (6) ◽  
pp. 383-392 ◽  
Author(s):  
G Schweitzer
Keyword(s):  
Robust Control ◽  
State Of The Art ◽  
Magnetic Bearing ◽  
Rotating Machinery ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Problems And Solutions ◽  
Safety And Reliability ◽  
Smart Machines

The application of magnetic bearings for rotating machinery has become state of the art and spans from research prototypes to industrial series. Users are aware that beyond functionality the aspects of safety and related areas become increasingly important. This survey addresses the issues of safety and reliability, being a part of dependability. It gives a review on existing approaches, and it shows numerous examples of problems and solutions. Review topics are safety-oriented design methods, software tools, redundancy, robust control, and retainer bearings. Finally, the concept of smart machines is introduced as a way for further improving safety and dependability of machinery with active magnetic bearings.

Simplified characteristics of active magnetic bearings

2002 ◽  
Vol 216 (5) ◽  
pp. 623-628 ◽  
Author(s):  
D J Peel ◽  
C M Bingham ◽  
Y Wu ◽  
D Howe
Keyword(s):  
Natural Vibration ◽  
Magnetic Bearing ◽  
Active Magnetic Bearing ◽  
Viscous Damping ◽  
Vibration Frequencies ◽  
Active Magnetic Bearings ◽  
Complex Dynamic ◽  
Speed Range ◽  
Constant Coefficients ◽  
System Characteristics

Traditionally, active magnetic bearing (AMB) systems are designed as an integral component of machines having generally complex dynamic characteristics. An AMB supported rotor has been tested over a speed range that included system natural vibration frequencies. A linear stiffness and viscous damping AMB characteristic with constant coefficients was identified which was independent of the overall system characteristics and which can thus provide simple and transferable data for a machine designer.

Dynamic Modeling and Analysis of Active Magnetic Bearings

2014 ◽  
Vol 494-495 ◽  
pp. 685-688
Author(s):  
Rong Gao ◽  
Gang Luo ◽  
Cong Xun Yan
Keyword(s):  
Dynamic Characteristic ◽  
Dynamic Modeling ◽  
Magnetic Bearing ◽  
Integrated System ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Modeling And Analysis ◽  
Amb System ◽  
Mathematics Method

Active magnetic bearing (AMB) system is a complex integrated system including mechanics, electronic and magnetism. In order to research for the basic dynamic characteristic of rotor supported by AMB, it is necessary to present mathematics method. The dynamics formula of AMB is established using theory means of dynamics of rotator and mechanics of vibrations. At the same tine, the running stability of rotor is analyzed and the example is presented in detail.

scholarly journals Development and Experimental Validation of Auxiliary Rolling Bearing Models for Active Magnetic Bearings (AMBs) Applications

2019 ◽  
Vol 2019 ◽  
pp. 1-19 ◽  
Author(s):  
Anna Tangredi ◽  
Enrico Meli ◽  
Andrea Rindi ◽  
Alessandro Ridolfi ◽  
Pierluca D’Adamio ◽  
...  
Keyword(s):  
Load Capacity ◽  
Critical Phenomenon ◽  
Magnetic Bearing ◽  
Design Tool ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Short Period ◽  
Auxiliary Bearing ◽  
Bearing System

Nowadays, the search for increasing performances in turbomachinery applications has led to a growing utilization of active magnetic bearings (AMBs), which can bring a series of advantages thanks to their features: AMBs allow the machine components to reach higher peripheral speeds; in fact there are no wear and lubrication problems as the contact between bearing surfaces is absent. Furthermore, AMBs characteristic parameters can be controlled via software, optimizing machine dynamics performances. However, active magnetic bearings present some peculiarities, as they have lower load capacity than the most commonly used rolling and hydrodynamic bearings, and they need an energy source; for these reasons, in case of AMBs overload or breakdown, an auxiliary bearing system is required to support the rotor during such landing events. During the turbomachine design process, it is fundamental to appropriately choose the auxiliary bearing type and characteristics, because such components have to resist to the rotor impact; so, a supporting design tool based on accurate and efficient models of auxiliary bearings is very useful for the design integration of the Active Magnetic Bearing System into the machine. This paper presents an innovative model to accurately describe the mechanical behavior of a complete rotor-dynamic system composed of a rotor equipped with two auxiliary rolling bearings. The model, developed and experimentally validated in collaboration with Baker Hughes a GE company (providing the test case and the experimental data), is able to reproduce the key physical phenomena experimentally observed; in particular, the most critical phenomenon noted during repeated experimental combined landing tests is the rotor forward whirl, which occurs in case of high friction conditions and greatly influences the whole system behavior. In order to carefully study some special phenomena like rotor coast down on landing bearings (which requires long period of time to evolve and involves many bodies and degrees of freedom) or other particular events like impacts (which occur in a short period of time), a compromise between accuracy of the results and numerical efficiency has been pursued. Some of the elements of the proposed model have been previously introduced in literature; however the present work proposes some new features of interest. For example, the lateral and the axial models have been properly coupled in order to correctly reproduce the effects observed during the experimental tests and a very important system element, the landing bearing compliant suspension, has been properly modelled to more accurately describe its elastic and damping effects on the system. Furthermore, the model is also useful to characterize the frequencies related to the rotor forward whirl motion.

The Oil-Free Shaft Line

1988 ◽  
Author(s):  
Bruno Wagner
Keyword(s):  
Vibration Control ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Present Stage ◽  
Shaft Line ◽  
Process Gas ◽  
Gas Seals ◽  
Length Reduction

This paper recalls the principles and main features of the active magnetic bearings and especially the advantages for turbomachines. Oil-free working and vibration control are part of them. Field experiences are described for different shaft line configurations. Step by step we are going to get totally rid of oil with the introduction of active magnetic bearings together with dry gas seals and gearless drive. Future machines will take the benefit of all this field experience. The trend of the design optimization is the active magnetic bearings in the process gas itself, for a length reduction of shafts. But at the present stage, the active magnetic bearing is a proven technology today.

scholarly journals The Application of Active Magnetic Bearings to a Natural Gas Pipeline Compressor

1986 ◽  
Author(s):  
E. G. Foster ◽  
V. Kulle ◽  
R. A. Peterson
Keyword(s):  
Natural Gas ◽  
Economic Assessment ◽  
Magnetic Bearing ◽  
Gas Pipeline ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
Active Magnetic Bearings ◽  
Dry Gas Seal ◽  
Natural Gas Pipeline ◽  
Operational Data

The installation and operation of an active magnetic bearing in conjunction with a modified mechanical dry gas seal on a natural gas pipeline compressor is presented. The emphasis of this paper is centered on the active magnetic bearing. The active magnetic bearing was developed by Société de Mécanique Magnétique (S2M) of Vernon France. The first successful application to a natural gas pipeline compressor was a co-operative effort between NOVA, AN ALBERTA CORPORATION, S2M, and Magnetic Bearing Incorporated (MBI) of Radford, Virginia. This paper represents a technical and economic assessment of the bearing, including installation and operational data.

scholarly journals Improvement of flexible rotor/active magnetic bearings system performance using pi-d control

2020 ◽  
Vol 40 (2) ◽  
pp. 112-123
Author(s):  
Adis Muminovic ◽  
Sanjin Braut ◽  
Adil Muminovic ◽  
Isad Saric ◽  
Goranka Štimac Rončević
Keyword(s):  
Pid Control ◽  
Real Life ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Active Magnetic Bearing ◽  
System Response ◽  
Active Magnetic Bearings ◽  
Flexible Rotor ◽  
Notch Filters ◽  
Common Control

Proportional–integral–derivative (PID) control is the most common control approach used to control active magnetic bearings system, especially in the case of supporting rigid rotors. In the case of flexible rotor support, the most common control is again PID control in combination with notch filters. Other control approaches, known as modern control theory, are still in development process and cannot be commonly found in real life industrial application. Right now, they are mostly used in research applications. In comparison to PID control, PI-D control implies that derivate element is in feedback loop instead in main branch of the system. In this paper, performances of flexible rotor/active magnetic bearing system were investigated in the case of PID and PI-D control, both in combination with notch filters. The performances of the system were analysed using an analysis in time domain by observing system response to step input and in frequency domain by observing a frequency response of sensitivity function.

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