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.

Disturbance suppression in active magnetic bearings with adaptive control and extended state observer

2019 ◽  
Vol 234 (2) ◽  
pp. 272-284
Author(s):  
Xudong Guan ◽  
Jin Zhou ◽  
Chaowu Jin ◽  
Yuanping Xu
Keyword(s):  
Adaptive Control ◽  
Control Method ◽  
State Observer ◽  
Magnetic Bearing ◽  
Extended State Observer ◽  
Magnetic Bearings ◽  
Active Magnetic Bearings ◽  
Extended State ◽  
Disturbance Suppression ◽  
Bearing System

Some sources of disturbance inevitably exist in magnetic bearings systems in the process of operation. This article proposes a disturbance suppression scheme for active magnetic bearings systems using an improved characteristic model-based all-coefficient adaptive control algorithm. First, the mathematical model of the magnetic bearing system is established. Then, by introducing the extended state observer into the adaptive control, the adaptive control method is improved. And the simulation of the combined control of the adaptive control and extended state observer is carried out based on mathematical model of controlled object. Simulation results demonstrate that this control method can not only adjust the control parameters online, but also estimate and compensate the disturbance in real time, which improves the control performance of the controller. Finally, the feasibility of adaptive control method with extended state observer is verified by experiments. When the sinusoidal disturbance signal is introduced at the 9000 r/min, the vibration displacement of the magnetic bearing system with the improved adaptive controller is reduced around 43%, which is in accordance with the theoretical results.

scholarly journals A Vibration Sensor-Based Method for Generating the Precise Rotor Orbit Shape with General Notch Filter Method for New Rotor Seal Design Testing and Diagnostics

Sensors ◽  
2021 ◽  
Vol 21 (15) ◽  
pp. 5249
Author(s):  
Karel Kalista ◽  
Jindrich Liska ◽  
Jan Jakl
Keyword(s):  
Notch Filter ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Harmonic Vibration ◽  
Filter Method ◽  
Vibration Exciter ◽  
Active Magnetic Bearings ◽  
Rotor Vibration ◽  
Seal Design ◽  
Exact Shape

Verification of the behaviour of new designs of rotor seals is a crucial phase necessary for their use in rotary machines. Therefore, experimental equipment for the verification of properties that have an effect on rotor dynamics is being developed in the test laboratories of the manufacturers of these components all over the world. In order to be able to compare the analytically derived and experimentally identified values of the seal parameters, specific requirements for the rotor vibration pattern during experiments are usually set. The rotor vibration signal must contain the specified dominant components, while the others, usually caused by unbalance, must be attenuated. Technological advances have made it possible to use magnetic bearings in test equipment to support the rotor and as a rotor vibration exciter. Active magnetic bearings allow control of the vibrations of the rotor and generate the desired shape of the rotor orbit. This article presents a solution developed for a real test rig equipped with active magnetic bearings and rotor vibration sensors, which is to be used for testing a new design of rotor seals. Generating the exact shape of the orbit is challenging. The exact shape of the rotor orbit is necessary to compare the experimentally and numerically identified properties of the seal. The generalized notch filter method is used to compensate for the undesired harmonic vibrations. In addition, a novel modified generalized notch filter is introduced, which is used for harmonic vibration generation. The excitation of harmonic vibration of the rotor in an AMB system is generally done by injecting the harmonic current into the control loop of each AMB axis. The motion of the rotor in the AMB axis is coupled, therefore adjustment of the amplitudes and phases of the injected signals may be tedious. The novel general notch filter algorithm achieves the desired harmonic vibration of the rotor automatically. At first, the general notch filter algorithm is simulated and the functionality is confirmed. Finally, an experimental test device with an active magnetic bearing is used for verification of the algorithm. The measured data are presented to demonstrate that this approach can be used for precise rotor orbit shape generation by active magnetic bearings.

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.

scholarly journals Magnetic Bearing Proposal Design for a General Unbalanced Rotor System enhanced because of using sensors/actuators based in nanostructures

2019 ◽  
Vol 95 ◽  
pp. 01002
Author(s):  
Jesus A. Calderón ◽  
Eliseo B. Barriga ◽  
Roland Mas ◽  
Luis Chirinos ◽  
Enrique Barrantes ◽  
...  
Keyword(s):  
Control Algorithm ◽  
Conveyor Belt ◽  
Magnetic Bearing ◽  
Magnetic Bearings ◽  
Active Magnetic Bearings ◽  
Uniform Rotation ◽  
Identification Process ◽  
Rotor Systems ◽  
Rotational Movement ◽  
Unbalanced Rotor

Rotor systems need bearings in order to keep uniformity of rotational movement transmission. However, bearingsgenerate friction and energy losses due to heating transmisssion through the friction; for this reason, mechanicak bearings are replaced by magnetic bearings owing to avoid energy losing because of friction. We designed Active Magnetic Bearings (AMB) to transmit rotational movement from source of movement (motor) through the rotor to the movement receptor (such as a conveyor belt). Magnetic Bearings need accuracy during System Identification process and a sophisticated control algorithm to get an uniform rotation movement transmission. In this work also it was analyzed and proved by simulations that Active Magnetic Bearings composed with sensors /actuators based in nanostructures are faster and robust compared with AMB based in traditional sensors/actuators. It because, nanostructures receive and send signals better way tan traditional sensors/actuators, because of high oredered nanoarrays improve sensor/actuator properties.

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.

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.

Nonlinear Calculation of Active Magnetic Bearings Dynamic Magnetic Field by Finite Element Method

2013 ◽  
Vol 392 ◽  
pp. 285-289
Author(s):  
Guo Ping Ding ◽  
Bin Gao
Keyword(s):  
Magnetic Field ◽  
Flux Density ◽  
Eddy Current ◽  
Open Loop ◽  
Air Gap ◽  
Magnetic Bearings ◽  
Active Magnetic Bearings ◽  
Flux Lines ◽  
Source Current ◽  
Dynamic Magnetic Field

Active magnetic bearings open-loop instability makes the features of dynamic magnetic field crucial to the control performance. We presented a nonlinear calculation of AMBs dynamic magnetic field by FEM. Firstly, we constructed a AMBs dynamic field FEM model considering the magnets nonlinear permeability; Secondly, we applied a harmonic current to the coils through 160 load steps and a zero magnetic potential boundary condition; Finally the field was solved and magnetic flux lines, air gap flux density and eddy current density were retrieved and analyzed. Because of the nonlinearity of eddy current, air gap flux density is not standard harmonic and lags behind the source current,and as magnetizing energy equalizes eddy current losses, air gap flux density approaches harmonic.

Vibration Control of Spur Geared Rotor Systems With Transmission Errors by Active Magnetic Bearings

2019 ◽  
Author(s):  
Gargi Majumder ◽  
Rajiv Tiwari
Keyword(s):  
Vibration Control ◽  
Transmission Error ◽  
Magnetic Bearings ◽  
Physical Contact ◽  
Vibration Measurement ◽  
Mesh Deformation ◽  
Control Force ◽  
Active Magnetic Bearings ◽  
Full Spectrum ◽  
Gear Mesh

Abstract Dynamic forces between the mating gears are generated due to the mesh deformation, gear eccentricities, transmission error, and gear run-out, which cause excessive vibration and noise. Study and control of these forced vibrations in gear box are vital to prevent any adverse effects on the gears and its supporting structures. Hence, this work presents a novel concept of active vibration control by introducing Active Magnetic Bearings (AMBs) on the shaft of a spur gearbox having conventional bearings as well. The AMB suppresses the response of the system by generating controlled electromagnetic forces based on the gear shaft vibration measurement. The AMB force is applied without any physical contact as opposed to mechanical forces in conventional bearings. A coupled torsional-lateral vibration analysis has been simulated with the effects of mesh deformation, gear eccentricities, transmission error, and gear run-out. The electromagnetic actuator is designed in such a way that a resultant radial control force can be developed with the help of forces in two mutually perpendicular directions. With a feedforward PID controller, the transverse vibration amplitude is observed to be suppressed to a considerable level. The frequency domain analysis is done using a full spectrum, which shows that multiple harmonics of gear mesh frequency is minimized simultaneously.

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