Active magnetic bearing: A new step for model-free control

International audienceThe newly introduced model-free control is applied to the stabilization of an active magnetic bearing, which is a most important industrial device. Experimental results are compared to those obtained via other control techniques, showing at least on-par performance with this very straightforward approach, which is moreover quite easy to implement

APPLICATION OF ARTIFICIAL NEURAL NETWORKS IN THE CONTEXT OF ACTIVE MAGNETIC BEARING CONTROL SYSTEMS

The article is devoted to the application of neural network methods and genetic algorithms in solving problems of controlling an electric drive of an active magnetic suspension. The method of rolling moment for eliminating an imbalance is considered. The scheme of the neural network controller and the curves of the transients in the open single-mass electromechanical system and in the system c of the neurocontrollers are presented

NLMS Based Adaptive Control of Stable Plants

In this paper we propose a new stable adaptive controller for stable plants, which may be non-minimum phase. The controller is composed of adaptive finite impulse response (FIR) filter in the feedback loop. This adaptive FIR filter is designed online as an L-delay approximate inverse system of the given stable plant. The solution of Diophantine equation is not involved in the design procedure. Hence the numerical problems associated with the solution of Diophantine equation are avoided. Computer simulation results and real time experimental results are included in the paper to demonstrate the effectiveness of the proposed method

Fourth International Symposium on Magnetic Suspension Technology

In order to examine the state of technology of all areas of magnetic suspension and to review recent developments in sensors, controls, superconducting magnet technology, and design/implementation practices, the Fourth International Symposium on Magnetic Suspension Technology was held at The Nagaragawa Convention Center in Gifu, Japan, on October 30 - November 1, 1997. The symposium included 13 sessions in which a total of 35 papers were presented. The technical sessions covered the areas of maglev, controls, high critical temperature (T(sub c)) superconductivity, bearings, magnetic suspension and balance systems (MSBS), levitation, modeling, and applications. A list of attendees is included in the document

Fuzzy modeling and control for conical magnetic bearings using linear matrix inequality

A general nonlinear model with six degree-of-freedom rotor dynamics and electromagnetic force equations for conical magnetic bearings is developed. For simplicity, a T-S (Takagi Sugeno) fuzzy model for the nonlinear magnetic bearings assumed no rotor eccentricity is first derived, and a fuzzy control design based on the T-S fuzzy model is then proposed for the high speed and high accuracy control of the complex magnetic bearing systems. The suggested fuzzy control design approach for nonlinear magnetic bearings can be cast into a linear matrix inequality (LMI) problem via robust performance analysis, and the LMI problem can be solved efficiently using the convex optimization techniques. Computer simulations are presented for illustrating the performance of the control strategy considering simultaneous rotor rotation tracking and gap deviations regulation

Cylindrical spinning rotor gauge — A new approach for vacuum measurement

The spinning rotor gauge (SRG) is one of the most interesting vacuum gauges ever made, covering a pressure range of over seven orders of magnitude, with minimal gas interference (no pumping, ionization or heating of the measured gas), and a great stability of less than 1% drift per year. But despite its remarkable properties, apparently the SRG has not been further developed since the eighties, when it gained commercial interest. In this context, this dissertation aims at providing a starting point for a new line of investigation regarding this instrument, focused on the rotor itself. A brief study of different rotor geometries is provided, including a comparison between a cylindrical rotor and a spherical one. A cylindrical spinning rotor gauge (CSRG) is then proposed, based on the original SRG, but requiring a completely new lateral damping system. A prototype was built and tested against a non calibrated reference gauge

Investigation on the Applicability of Active Magnetic Bearings to High Speed Spindle Design

A novel concept applicable to the control of spindles at high speed is developed by using active magnetic bearings (AMBs) that are non-contact and of low vibration. Extensive literature reviews explicate that the broad applications of AMBs are severely hampered by the incomplete description of the underlying electro-magnetic-mechanical dynamics. The thesis considers the gyroscopic effect inherent of a flexible rotor and explores the geometry coupling of the electro-magnetic actuators to the formulation of a comprehensive nonlinear AMB-rotor model. The model provides the basis for the creation of a novel time-frequency control algorithm whose derivation requires no linearization or mathematical simplification of any kind, thus allowing the model system to retain its true fundamental characteristics. Unlike proportional-integral-derivative (PID) controllers that are dominant in most if not all AMB configurations, the controller developed for the research is inspired by the wavelet-based nonlinear time-frequency control methodology that incorporates the basic notions of online system identification and adaptive control. Wavelet filter banks and filtered-x least-mean-square (LMS) algorithm are two of the major salient physical features of the controller design, with the former providing concurrent temporal and spectral resolutions needed for identifying nonlinear states of motion and the latter ensuring the dynamic stability of the AMB-rotor system at all operating speeds subjected to the presence of external disturbances. It is shown in the thesis that the vibration of the rotor is unconditionally controlled by maintaining the mandatory 0.55 mm air gap at 150,000 and 187,500 rpm subject to a tight spatial constraint (tolerance) of the order of 0.1375mm. System responses with and without considering the gyroscopic motion and geometry coupling are studied to demonstrate the negative impact on misinterpreting the AMB-rotor dynamics when the two effects are neglected. The case of an impact of 5,000m/s2 in magnitude and 0.001 seconds in duration at 187,500rpm is also investigated to establish the robustness of the controller design. The time responses of all the cases considered are both temporally bounded and spectrally bandwidth-limited, thus demonstrating the effectiveness of the wavelet-based time-frequency controller design in mitigating the inherent instability of the AMB-rotor system at extreme speeds