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magnetic-bearings
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Control of shaft vibrations on magnetic bearings using neural network and sliding mode controller
, Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis - 2004, Manchester, 19 July 2004 through 22 July 2004 ; Volume 1 , 2004 , Pages 787-793 ; 0791841731 (ISBN); 9780791841730 (ISBN) ; Salarieh, H ; Sharif University of Technology
American Society of Mechanical Engineers
2004
Abstract
This article discusses a method for complete control of the dynamics of a rotating shaft on magnetic bearings under the effects of mass imbalance. The electromagnetic bearings used in this research are 2 four-pole bearing at the two ends of the rotor, which are actuated by differential currents. Full dynamic behavior of 3- dimensional rigid rotor and its effects on dynamic model are included. The effects of rotating mass unbalance are also included in the equations. The geometric couplings between electromagnetic forces of the coils are included as uncertainty. By using sliding mode controller and a neural network to estimate the system nonlinear-coupled equations, in a way suitable for...
Sensor runout compensation in active magnetic bearings via an integral adaptive observer
, Article Control Engineering Practice ; Volume 48 , 2016 , Pages 111-118 ; 09670661 (ISSN) ; Habibollahi, A ; Behzad, M ; Salarieh, H ; Mehdigholi, H ; Sharif University of Technology
Elsevier Ltd
Abstract
Sensor runout is one of the main sources of harmonic disturbances in active magnetic bearing systems. This type of the disturbance not only causes harmonic vibrations in the system but also changes the steady-state position of the axis of rotation from the geometric center of the AMB. In this paper, an integral adaptive observer is proposed to identify the dc and harmonic content of the sensor runout and to estimate the states of the system at the same time. The Lyapunov method is used to prove asymptotic stability of the proposed observer. Unlike the proportional observer which amplifies the measurement error, the sensor runout can be completely compensated when the states of the integral...
Pseudospectral optimal control of active magnetic bearing systems
, Article Scientia Iranica ; Vol. 21, Issue. 5 , 2014 , pp. 1719-1725 ; ISSN: 10263098 ; Livani, M ; Sharif University of Technology
Abstract
In this paper, an optimal control framework is formed to control rotor-Active Magnetic Bearing (AMB) systems. The multi-input-multi-output non-affine model of AMBs is well established in the literature and represents a challenging problem for control design, where the design requirement is to keep the rotor at the bearing centre in the presence of external disturbances. To satisfy the constraints on the states and the control inputs of the AMB nonlinear dynamics, a nonlinear optimal controller is formed to minimize tracking error between the current and desired position of the rotor. To solve the resulted nonlinear constrained optimal control problem, the Gauss Pseudospectral Collocation...
Design and Implementation of an Observer-Based Controller on a 3-Pole Active Magnetic Bearing Test Rig
, Ph.D. Dissertation Sharif University of Technology ; Behzad, Mehdi (Supervisor) ; Mehdigholi, Hamid (Supervisor) ; Salarieh, Hassan (Co-Advisor)
Abstract
Magnetic bearings have been used in industry to achieve an acceptable performance, high precision and vibration suppression of rotating machinery in recent decades.The absence of physical contact between the bearing and rotating components provides access to high rotational speeds which is a problem in conventional bearings.In addition, capabilities such as stiffness and damping adjustment can be used to reduce the harmonic vibrations caused by mass unbalance. The unbalance compensation is one of the main topicswhich has attracted the attention of many researchers in the field of rotordynamics. The aim of this thesis is to design and fabricatea three-pole active magnetic bearing test rig and...
Linear output feedback control of a three-pole magnetic bearing
, Article IEEE/ASME Transactions on Mechatronics ; Vol. 19, issue. 4 , 2014 , pp. 1323-1330 ; ISSN: 10834435 ; Behzad, M ; Salarieh, H ; Mehdigholi, H ; Sharif University of Technology
Abstract
The design and implementation of linear and nonlinear control methods for a three-pole active magnetic bearing (AMB) is presented in this paper. It is shown that the system has nearly linear dynamics by adding a bias to coil currents. A decentralized PID feedback law and an integral sliding mode controller are proposed and the unknown state variables of the system are estimated by the Kalman filter. The optimal gains of the linear controller are determined by the LQG technique. To evaluate the effectiveness of the proposed controllers, they are implemented on an experimental setup. The experimental results show that the proposed methods can effectively stabilize the three-pole AMB. The...
Performance verification of saturated IPM bearingless motors considering magnetic pull variation
, Article Proceedings - 2016 IEEE International Power Electronics and Motion Control Conference, PEMC 2016, 25 September 2016 through 28 September 2016 ; 2016 , Pages 643-649 ; 9781509017980 (ISBN) ; Nasiri Gheidari, Z ; Rahman, A ; Sharif University of Technology
Institute of Electrical and Electronics Engineers Inc
2016
Abstract
Interior permanent magnet (IPM) bearingless motors are becoming a good choice for high-speed applications. In these motors, reducing the thickness of the PM leads to the increase of the radial forces which affects the demagnetizing fields. Various types of PM motors have so far been recommended for enhancement of the radial forces and torque. In the proposed IPM motor the d-axis flux-linkage and the q-axis torque component are raised due to the armature reaction and this saturates the stator teeth. In addition, the magnetic attraction force generated by displacement force depends on the armature reaction. The mathematical model of IPM bearingless motor based on the dq transformation,...
Hybrid control of a three-pole active magnetic bearing
, Article Mechatronics ; Volume 39 , 2016 , Pages 28-41 ; 09574158 (ISSN) ; Salarieh, H ; Alasty, A ; Darbandi, S. M ; Sharif University of Technology
Elsevier Ltd
Abstract
The design and implementation of the hybrid control method for a three-pole active magnetic bearing (AMB) is proposed in this paper. The system is inherently nonlinear and conventional nonlinear controllers are a little complicated while the proposed hybrid controller has a piecewise linear form, i.e., linear in each sub-region. A state-feedback hybrid controller is designed in this study and the unmeasurable states are estimated by an observer. The gains of the hybrid controller are obtained by the LQR method in each sub-region. To evaluate the performance, the designed controller is implemented on an experimental setup. The experimental results show that the proposed method can efficiently...
Stability Analysis of Rotor Bearing Systems via Lyapunov's Direct Method
, M.Sc. Thesis Sharif University of Technology ; Zohoor, Hassan (Supervisor)
Abstract
Due to the use of rotor dynamics, in the rotating systems such as pumps, turbines and machine tool spindle gained special significance in recent decades and a growing need for rotating machines with high speed, leading to extensive research in this area. Due to instability in the dynamics of these systems, check the stability of the rotor system has been given special emphasis, so that studies and research in terms of models and methods allocated to this topic. The project analyzed the stability of a rotor that includes an elastic shaft is placed on the bearings as it is objective. From point of modeling, the rotor is modeled using Timoshenko beam theory and the rotor mounted on bearing with...
Harmonic disturbance attenuation in a three-pole active magnetic bearing test rig using a modified notch filter
, Article JVC/Journal of Vibration and Control ; Volume 23, Issue 5 , 2017 , Pages 770-781 ; 10775463 (ISSN) ; Behzad, M ; Salarieh, H ; Mehdigholi, H ; Sharif University of Technology
Abstract
This study is concerned with the problem of harmonic disturbance rejection in active magnetic bearing systems. A modified notch filter is presented to identify both constant and harmonic disturbances caused by sensor runout and mass unbalance. The proposed method can attenuate harmonic displacement and currents at the synchronous frequency and its integer multiples. The reduction of stability is a common problem in adaptive techniques because they alter the original closed-loop system. The main advantage of the proposed method is that it is possible to determine the stability margins of the system by few parameters. The negative phase shift of the modified notch filter can be tuned to...
Design and Implementation of a Robust Control Method for Rotor Tabilizing in a Three-pole Magnetic Bearing
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mehdi (Supervisor)
Abstract
High speed and high accuracy are two of the major trends for many systems in the 21st century, such as machine tools and semiconductor equipment. For the purpose of high speed, it is well known that active magnetic bearing (AMB) is an inevitable substitute for conventional bearings. The noncontact nature of AMB brings up many advantages over the conventional bearing, including energy efficiency, low wearing, long life span, and absence of lubrication. Hence, AMBs are especially essential for high-speed rotating devices nowadays.
While the 3-pole AMB has been proposed for many years, it received little attention due to the magnetic coupling between poles that makes the 3-pole AMB system...
While the 3-pole AMB has been proposed for many years, it received little attention due to the magnetic coupling between poles that makes the 3-pole AMB system...
Estimation and Control of Harmonic Disturbances Due to Mass Unbalance and Sensor Runout in Three-Pole Active Magnetic Bearing
, M.Sc. Thesis Sharif University of Technology ; Behzad, Mehdi (Supervisor) ; Manzuri, Mohammad Taghi (Co-Advisor)
Abstract
Disturbances due to sensor runout and mass unbalance are the main sources of harmonic disturbances in active magnetic bearing systems. Existence of this type of the disturbance not only causes harmonic vibrations in the system but also changes the steady-state position of the axis of rotation from the geometric center of the AMB. In this research, an observer-based control method used to estimate and reject this disturbance. Proposed integral observer estimates dc and harmonic content of the sensor runout and also estimates the states of the system at the same time with good precision. Lyapunov method is used to prove asymptotic stability of the proposed observer and demonstrated that sensor...
Sliding mode control of electromagnetic system based on fuzzy clustering estimation (an experimental study)
, Article Proceedings of the 7th Biennial Conference on Engineering Systems Design and Analysis ; Volume 1 , 2004 , Pages 843-850 ; ISBN: 0791841731 ; ISBN: 9780791841730 ; Salarieh, H ; Shabani, R ; Sharif University of Technology
Abstract
Using the combination of fuzzy clustering estimation and sliding mode control, a technique for controlling the magnetic levitation (ML) systems is introduced. This technique is applied to an experimental setup of an ML system for investigating the method derived. The system considered, is a symmetric rotor supported by a cantilever load cell beam and excited by only one electromagnet of a 4-pole magnetic bearing setup. After demonstrating the experimental setup instruction and the specifications of its parts, the clustering, and the sliding mode control methods are explained briefly, then the quality of implementing the techniques to the setup is described step by step. Finally, the results...
Nonlinear identification of electro-magnetic force model
, Article Journal of Zhejiang University: Science A ; Volume 11, Issue 3 , 2010 , Pages 165-174 ; 1673565X (ISSN) ; Tariverdilo, S ; Salarieh, H ; Sharif University of Technology
2010
Abstract
Conventional attractive magnetic force models (proportional to the coil current squared and inversely proportional to the gap squared) cannot simulate the nonlinear responses of magnetic bearings in the presence of electromagnetic losses, flux leakage or saturation of iron. In this paper, based on results from an experimental set-up designed to study magnetic force, a novel parametric model is presented in the form of a nonlinear polynomial with unknown coefficients. The parameters of the proposed model are identified using the weighted residual method. Validations of the model identified were performed by comparing the results in time and frequency domains. The results show a good...
Determination of Domain of Attraction in Active Magnetic Bearing
, M.Sc. Thesis Sharif University of Technology ; Mobed, Mohammad (Supervisor)
Abstract
Magnetic bearings have been introduced in recent decades to overcome the problem of energy loses due to friction in bearings of rotating machinery. In magnetic bearings, the rotor is suspended by magnetic forces without any friction. These bearings are of the two types of passive and active. In Passive Magnetic Bearings (PMB), magnetic forces are generated by permanent magnets and have the ability to tolerate a small distribution. In Active Magnetic Bearings (AMB) magnetic forces are generated by electromagnets and have the ability to tolerate larger distributions than the PMB can. Since AMB is inherently unstable, it is necessary to use controllers to stabilize it. Due to the nonlinear...
Nonlinear parametric identification of magnetic bearings
, Article Mechatronics ; Volume 16, Issue 8 , 2006 , Pages 451-459 ; 09574158 (ISSN) ; Shabani, R ; Sharif University of Technology
2006
Abstract
This paper proposes a new electromagnetic force model and its parameter identification method. As a case study, the parameters of the proposed model for an experimental electromagnetic bearing system are obtained using extended Kalman filter (EKF). The experimental setup includes a symmetric rigid rotor which is disturbed by the electromagnet of a magnetic bearing. Experimental results show that the system response to harmonic excitation includes super-harmonic terms which are not shown by the well-known conventional electromagnetic force model. This shortcoming necessitates an investigation to propose a more realistic electromagnetic force model. Based on the observations of the system...
Designing Hybrid Controller, Impleimentation on Experiment Model and Proving Stability for 3-Pole AMB
, M.Sc. Thesis Sharif University of Technology ; Salarieh, Hassan (Supervisor) ; Alasti, Aria (Supervisor)
Abstract
The design and implementation of the hybrid control method for a three-pole active magnetic bearing (AMB) is proposed in this paper. The system is inherently nonlinear and conventional nonlinear controllers are a little complicated while the proposed hybrid controller has a piecewise linear form, i.e., linear in each sub-region. A state-feedback hybrid controller is designed in this study and the unmeasurable states are estimated by an observer. The gains of the hybrid controller are obtained by the LQR method in each sub-region. To evaluate the performance, the designed controller is implemented on an experimental setup. The experimental results show that the proposed method can efficiently...