Magnetic Bearings. Experimental Verification on Gain Scheduled H.INF. Robust Control of a Magnetic Bearing.

The thrust position of the magnetic levitation rotor can be changed, bringing convenience to the practical application of cold compressors. This paper derives the mathematical model of asymmetric thrust magnetic bearings for a cold compressor and analyzes the changes in the system characteristics with the equilibrium position. By constructing PID controllers associated with the structural parameters of the magnetic bearing, the adaptive adjustment of the control parameters under different balanced position commands is realized. The simulation and experimental results prove that the gain-scheduled control method proposed in this paper can achieve a robust stability of the rotor in the range of 50 to 350 μm, and not at the cost of the response speed, adjustment time, and overshoot. The research results have reference significance for the structure design of asymmetric thrust magnetic bearings and play an important role in the commissioning and performance improvement of cold compressors.

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

Proceedings of the Institution of Mechanical Engineers Part I Journal of Systems and Control Engineering ◽

10.1243/095965105x33491 ◽

2005 ◽

Vol 219 (6) ◽

pp. 383-392 ◽

Cited By ~ 12

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.

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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 ◽

10.3390/s21155249 ◽

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.

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Application of gain scheduled H/sub ∞/ robust controllers to a magnetic bearing

IEEE Transactions on Control Systems Technology ◽

10.1109/87.531915 ◽

1996 ◽

Vol 4 (5) ◽

pp. 484-493 ◽

Cited By ~ 85

Author(s):

F. Matsumura ◽

T. Namerikawa ◽

K. Hagiwara ◽

M. Fujita

Keyword(s):

Magnetic Bearing ◽

Robust Controllers ◽

Gain Scheduled

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Experimental Verification of the Hybrid Magnetic Bearing Operation

2018 International Conference on Applied Electronics (AE) ◽

10.23919/ae.2018.8501426 ◽

2018 ◽

Cited By ~ 1

Author(s):

Jan Vitner ◽

Jiri Pavelka ◽

Jiri Lettl

Keyword(s):

Experimental Verification ◽

Magnetic Bearing

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Sliding Mode Output Feedback Control of a Flexible Rotor via Magnetic Bearings

Volume 5: Manufacturing Materials and Metallurgy; Ceramics; Structures and Dynamics; Controls, Diagnostics and Instrumentation; Education ◽

10.1115/98-gt-407 ◽

1998 ◽

Cited By ~ 1

Author(s):

A. S. Lewis ◽

A. Sinha ◽

K. W. Wang

Keyword(s):

Differential Equations ◽

Sliding Mode ◽

Output Feedback Control ◽

Angular Speed ◽

Magnetic Bearing ◽

Magnetic Bearings ◽

Control Parameters ◽

Flexible Rotor ◽

Rotor Imbalance ◽

Feedback Algorithm

A sliding mode feedback algorithm is proposed to control the vibration of a flexible rotor supported by magnetic bearings. It is assumed that the number of states is greater than the number of sensors. A mathematical model of the rotor/magnetic bearing system is presented in terms of partial differential equations. These equations are then discretized into a finite number of ordinary differential equations through Galerkin’s method. The sliding mode control law is designed to be robust to rotor imbalance and transient disturbances. A boundary layer is introduced around each sliding hyperplane to eliminate the chattering phenomenon. The results from numerical simulations are presented which not only corroborate the validity of the proposed controller, but also show the effects of various control parameters as a function of the angular speed of the rotor. In addition, results are presented that indicate how the current required by the magnetic bearings is affected by control parameters and the angular speed of the rotor.

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