Fault detection and tolerance in synchronous vibration control of rotor—magnetic bearing systems

2001 ◽  
Vol 215 (12) ◽  
pp. 1401-1416 ◽  
Author(s):  
M N Sahinkaya ◽  
M O T Cole ◽  
C R Burrows
Keyword(s):  
Vibration Control ◽  
Magnetic Bearing ◽  
Open Loop ◽  
Magnetic Bearings ◽  
Control Technique ◽  
Effective Control ◽  
System Response ◽  
Rotor Support ◽  
Measured System ◽  
Control Forces

The use of magnetic bearings in rotating machinery provides contact-free rotor support, and allows vibration control using both closed-loop and open-loop strategies. One of the simplest and most effective methods to reduce synchronous lateral vibration when using magnetic bearings is through an open-loop adaptive control technique, in which the amplitude and phase of synchronous magnetic control forces are adjusted automatically to minimize the measured vibrations along the rotor. However, transducer malfunction, or faults in the signal-processing channels, may cause the controller to adapt incorrectly, with unwanted and possibly catastrophic effects. It is shown that an extension to the control strategy, which utilizes the variances of the measured system response and identified parameters, enables the faults to be detected and accounted for so that a modified control action can achieve continued and effective control of the synchronous vibration. The approach is extended further to identify changes in external factors, such as unbalance and rotor dynamics. Various faults and perturbations are examined experimentally, and the ability of the controller to detect and compensate for these changes is demonstrated.

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.

Active vibration control experiments on an AgustaWestland W30 helicopter airframe

2011 ◽  
Vol 226 (6) ◽  
pp. 1504-1516 ◽  
Author(s):  
J E Mottershead ◽  
M Ghandchi Tehrani ◽  
S James ◽  
P Court
Keyword(s):  
Vibration Control ◽  
Frequency Response ◽  
Closed Loop ◽  
Vibration Suppression ◽  
Active Vibration Control ◽  
Input Voltage ◽  
Open Loop ◽  
Control Technique ◽  
Response Functions ◽  
Frequency Response Functions

This article describes the practical application of a vibration control technique, developed by the authors and known as the receptance method, to the AgustaWestland W30 helicopter airframe in the vibration test house at Yeovil. The experimental work was carried out over a total of 5 days in two visits to the Yeovil site during February and March 2011. In the experiments, existing electro-hydraulic actuators were used; they were built into the airframe structure and originally designed for vibration suppression by the methodology known as active control of structural response developed at the AgustaWestland Helicopters site in Yeovil. Accelerometers were placed at a large number of points around the airframe and an initial open-loop modal test was carried out. In a subsequent test, at higher actuator input voltage, considerable non-linearity was discovered, to the extent that the ordering of certain modes had changed. The vibration modes were, in general, heavily damped. Control was implemented using measured frequency response functions obtained at the higher input level. After acquiring the necessary measurements, simulations were carried out and the controller was implemented using MATLAB/Simulink and dSPACE. The closed-loop poles were mostly assigned with small real parts so that the system would be lightly damped and sharp peaks would be clearly apparent in the measured closed-loop frequency response functions. Locations of the open- and closed-loop poles in the complex s-plane were obtained to verify that the required assignment of poles had taken place.

Neural Network Emulation of a Magnetically Suspended Rotor

2004 ◽  
Vol 126 (2) ◽  
pp. 373-384 ◽  
Author(s):  
A. Escalante ◽  
V. Guzma´n ◽  
M. Parada ◽  
L. Medina ◽  
S. E. Diaz
Keyword(s):  
Neural Network ◽  
Virtual Instrument ◽  
High Speed ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
System Response ◽  
The Neural Network ◽  
Artificial Neurons ◽  
Position Data ◽  
System 2

The use of magnetic bearings in high speed/low friction applications is increasing in industry. Magnetic bearings are sophisticated electromechanical systems, and modeling magnetic bearings using standard techniques is complex and time consuming. In this work a neural network is designed and trained to emulate the operation of a complete system (magnetic bearing, PID controller, and power amplifiers). The neural network is simulated and integrated into a virtual instrument that will be used in the laboratory both as a teaching and a research tool. The main aims in this work are: (1) determining the minimum amount of artificial neurons required in the neural network to emulate the magnetic bearing system, (2) determining the more appropriate ANN training method for this application, and (3) determining the errors produced when a neural network trained to emulate system operation with a balanced rotor is used to predict system response when operating with an unbalanced rotor. The neural network is trained using as input the position data from the proximity sensors; neural network outputs are the control signals to the coil amplifiers.

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.

Adaptive Control of Active Magnetic Bearings to Prevent Rotor-Bearing Contact

2006 ◽  
Author(s):  
Abdul-Hadi G. Abulrub ◽  
M. Necip Sahinkaya ◽  
Clifford R. Burrows ◽  
Patrick S. Keogh
Keyword(s):  
Adaptive Control ◽  
Sudden Change ◽  
Experimental System ◽  
Magnetic Bearing ◽  
Open Loop ◽  
Contact Dynamics ◽  
Magnetic Bearings ◽  
Control Force ◽  
Active Magnetic Bearings ◽  
The Impact

Active Magnetic Bearing (AMB) systems offer various advantages over conventional bearings but due to their limited force capacity, with high levels of vibrations the rotor may come into contact with retainer bearings. Under conventional PID control, when a rotor comes into contact with its retainer bearings it remains in contact, until the rotor is run down and the system shut down. This may not be acceptable in some applications, such as aerospace and automotive applications. In this paper, a recursive open-loop adaptive control (ROLAC) algorithm is presented, as an extension of the existing open loop adaptive controller (OLAC), that updates the control force amplitude and phase at each sampling period for rapid response to changes in external excitations. The effectiveness of the algorithm in counteracting a sudden change of rotor unbalance is demonstrated by simulation and experimental results. The experimental system consists of a flexible 2 m long rotor with a mass of 100 kg supported by two radial active magnetic bearings. A simulation model of the system, including the contact dynamics, was used to assess the feasibility of the suggested controller before applying it to the experimental system. Depending on excitation levels, it is shown that the proposed controller is fast enough to prevent contact in most cases. If contact does occur the impact is minimized, and the method is able to recover the rotor position quickly. The proposed controller is implemented in real time and applied to the experimental system. It is shown that the controller works efficiently as predicted by the simulation studies.

Research on method for adaptive imbalance vibration control for rotor of variable-speed mscmg with active-passive magnetic bearings

2016 ◽  
Vol 23 (2) ◽  
pp. 167-180 ◽  
Author(s):  
Peiling Cui ◽  
Jingxian He ◽  
Jiancheng Fang ◽  
Xiangbo Xu ◽  
Jian Cui ◽  
...  
Keyword(s):  
Vibration Control ◽  
Attitude Control ◽  
Control Method ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
System Stability ◽  
Variable Speed ◽  
Control Moment ◽  
Vibration Compensation ◽  
Main Factor

Imbalance vibration control for rotor is the main factor affecting attitude control performance for satellite using magnetically suspended control moment gyro (MSCMG). The method for adaptive imbalance vibration control for the rotor of variable-speed MSCMG with active-passive magnetic bearings is investigated in this paper. Firstly, on the basis of feedforward compensation, a rotor model for the imbalance vibration of variable-speed MSCMG with active-passive magnetic bearings is built, and the main factor affecting imbalance vibration compensation is also analyzed. Then, power amplifier parameter modifier with control switches is designed to eliminate the effects of time-varying parameters on the imbalance vibration compensation precision. The adaptive imbalance vibration control based on this modifier not only has high compensation precision, but also can control the frequency of parameter adjustment according to the compensation precision. Besides, since the passive magnetic bearing displacement stiffness of the rotor of variable-speed MSCMG with active-passive magnetic bearings cannot be obtained accurately, displacement stiffness modifier is employed. Finally, stability analysis is made on the imbalance vibration control system, and the range of rotation speed to ensure system stability is derived. Simulation results show that, imbalance vibration control method proposed in this paper can suppress the imbalance vibration of the rotor of variable-speed MSCMG with active-passive magnetic bearings effectively and has high precision.

Self-Sensing Active Magnetic Dampers for Vibration Control

2009 ◽  
Vol 131 (6) ◽  
Author(s):  
Angelo Bonfitto ◽  
Xavier De Lépine ◽  
Mario Silvagni ◽  
Andrea Tonoli
Keyword(s):  
Vibration Control ◽  
Closed Loop ◽  
Flexible Structures ◽  
Open Loop ◽  
System Response ◽  
Model Parameters ◽  
Loop Model ◽  
Single Degree Of Freedom ◽  
Luenberger Observer ◽  
Model Response

The aim of this paper is to investigate the potential of a self-sensing strategy in the case of an electromagnetic damper for the vibration control of flexible structures and rotors. The study has been performed in the case of a single degree of freedom mechanical oscillator actuated by a couple of electromagnets. The self-sensing system is based on a Luenberger observer. Two sets of parameters have been used: nominal ones (based on simplifications on the actuator model) and identified ones. In the latter case, the parameters of the electromechanical model used in the observer are identified starting from the open-loop system response. The observed states are used to close a state-feedback loop with the objective of increasing the damping of the system. The results show that the damping performance are good in both cases, although much better in the second one. Furthermore, the good correlation between the closed-loop model response and the experimental results validates the modeling, the identification procedure, the control design, and its implementation. The paper concludes on a sensitivity analysis, in which the influence of the model parameters on the closed-loop response is shown.

Full-Size Rotordynamic Test Rig for Magnetic and Auxiliary Bearing Testing and Initial Results

2012 ◽  
Author(s):  
Oscar De Santiago ◽  
Víctor Solórzano ◽  
Sergio Díaz
Keyword(s):  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Test Rig ◽  
Transient Event ◽  
Electric Motor Drives ◽  
Compressor Rotor ◽  
Rotor Support ◽  
Rotor Stator Interaction ◽  
Auxiliary Bearing ◽  
Floating Platforms

Recent challenges in turbocompresor design include applications in subsea installations as well as remote operation in unmanned floating platforms. These applications benefit from oil-free operation which solves technical hurdles while being environmentally friendly. The most mature oil-free rotor support technology today is the magnetic bearing which is being used by several manufacturers as their standard solution to these advanced applications. These systems require auxiliary bearings to contain the rotor in case of a power failure to the magnetic bearings or a transient event. In general, there exists the need to develop commercial solutions for auxiliary bearings to extend its life, in particular regarding cumulative damage associated to drop events. This paper presents the design of a configurable test rig that can accommodate different rotor sizes, up to 1200 mm in bearing span, and 711 mm diameter wheels. The rig can also accommodate bearing sizes up to 229 mm. Rig pedestals can fit different bearing types such as magnetic bearings and/or auxiliary bearings independently, including oil bearings for comparison purposes. Misalignment and support flexibility effects are also possible. A 15.5 kW, variable speed electric motor drives the test rotor up to a speed limit of 10,000 rpm. Initial experiments on auxiliary bearings are shown for a 5-impeller, 57.8 kg, subcritical compressor rotor without drop events to study the baseline dynamic behavior of roller-element bearings (with inner clearance) on soft supports (o-rings). These experiments are presented to illustrate non-linear vibration regimes present during rotor-stator interaction with a highly unbalanced rotor. Experimental evidence presented can be used to fine-tune current auxiliary bearingmodels to improve rotordynamic predictive codes.

Vibration control of multi-mode rotor-bearing systems

1983 ◽  
Vol 386 (1790) ◽  
pp. 77-94 ◽  
Keyword(s):  
Vibration Control ◽  
Least Squares Method ◽  
Control Strategies ◽  
Open Loop ◽  
External Control ◽  
Wide Range ◽  
Rotor Bearing ◽  
Optimum Response ◽  
Control Forces ◽  
Adaptive Vibration Control

This paper presents a computationally fast and efficient least-squares method to minimize the vibration of any general rotor-bearing system by the application of external control forces. The D-optimality concept is used to optimize the force locations. The proposed method provides a wide range of statistical information, and the sensitivity of the optimum response to changes in the control forces. Magnetic bearings can be applied to implement the open-loop adaptive vibration control strategies outlined in the paper. These components can also be used to inject a multi-frequency test signal as required for identi­fication studies.

Design of Magnetic Bearings for Rotor Systems With Harmonic Excitations

1991 ◽  
Author(s):  
D. Dhar ◽  
L. E. Barrett
Keyword(s):  
Harmonic Excitation ◽  
Magnetic Bearing ◽  
Least Square ◽  
Magnetic Bearings ◽  
Rotor Systems ◽  
Bearing Stiffness ◽  
Control Forces ◽  
Stiffness And Damping ◽  
Flexible Rotor Systems ◽  
Modal Coordinates

Abstract This paper presents a method for calculating the control forces and the bearing stiffness and damping coefficients to control the response of multi-mass flexible rotor systems mounted on magnetic bearings and subjected to unbalance or harmonic excitation forces. The capability for inclusion of hydrodynamic bearings is retained to model seal effects or to permit the design of magnetic bearings for hybrid systems. Control forces at the magnetic bearing locations are evaluated based on the desired shaft response specified by the modal coordinates. These forces are determined such that the error between the desired response and the achieved response is minimized in a least-square sense. Equivalent bearing coefficients are calculated from the control forces and the achieved response, which when superimposed on the nominal bearing coefficients yield the resultant magnetic bearing coefficients required for control. An example case is presented where control of rotor response has been attempted at the first and the second unbalance critical speeds. The results demonstrate appreciable improvement in response using magnetic bearings.

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