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1
Li, Peichao. "Active touchdown bearing control in magnetic bearing systems." Thesis, University of Bath, 2015. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.678846.
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Šindelář, Petr. "Návrh hybridního magnetického ložiska." Master's thesis, Vysoké učení technické v Brně. Fakulta elektrotechniky a komunikačních technologií, 2021. http://www.nusl.cz/ntk/nusl-443089.
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The thesis deals with the design of a hybrid magnetic bearing. This is an extension of the issue of common bearings in high-speed motors. The work is divided into three parts. A general theory of magnetic bearings is described in the first part. The second part deals with the mathematical description of the bearing. A proposal of specific hybrid magnetic bearing is described in the third part. The bearing for the motor was already designed. It is a 45000rpm motor with a power output of 12 kW. This thesis aims to create a design of hybrid magnetic bearing with magnets to create a permanent magnetic field and coils to regulate forces to stabilize the rotor and limit vibrations. The practical design includes mathematical calculation in Matlab and computer simulation based on the finite element method in ANSYS Maxwell.
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Soukup, Vladimir. "Analysis and design of a magnetic bearing." Thesis, University of British Columbia, 1988. http://hdl.handle.net/2429/28519.
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Magnetic bearings have recently begun to be employed in rotating machinery for vibration
reduction, elimination of oil lubrication problems and prevention of failures. This thesis presents an analysis and design of an experimental model of a magnetic suspension system. The magnetic bearing, its control circuit and the supported object
are modeled. Formulas are developed for the position and current stiffness of the bearing and the analogy with a mechanical system is shown. The transfer function is obtained for the control and experimental results are presented for the double pole one axis magnetic support system.Applied Science, Faculty of
Electrical and Computer Engineering, Department of
Graduate
4
Huang, Yang, and S3110949@student rmit edu au. "Model Predictive Control of Magnetic Bearing System." RMIT University. Electrical and Computer Engineering, 2007. http://adt.lib.rmit.edu.au/adt/public/adt-VIT20080430.152045.
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Magnetic Bearing Systems have been receiving a great deal of research attention for the past decades. Its inherent nonlinearity and open-loop instability are challenges for controller design. This thesis investigates and designs model predictive control strategy for an experimental Active Magnetic Bearing (AMB) laboratory system. A host-target development environment of real-time control system with hardware in the loop (HIL) is implemented. In this thesis, both continuous and discrete time model predictive controllers are studied. In the first stage, local MPC controllers are applied to control the AMB system; and in the second stage, concept of supervisory controller design is then investigated and implemented. Contributions of the thesis can be summarized as follows; 1. A Discrete time Model Predictive Controller has been developed and applied to the active magnetic bearing system. 2. A Continuous time Model Predictive Controller has been developed and applied to the active magnetic bearing system. 3. A frequency domain identification method using FSF has been applied to pursue model identification with respect to local MPC and magnetic bearing system. 4. A supervisory control strategy has been applied to pursue a two stages model predictive control of active magnetic bearing system.
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Konkola, Paul Thomas 1973. "Magnetic bearing stages for electron beam lithography." Thesis, Massachusetts Institute of Technology, 1998. http://hdl.handle.net/1721.1/9315.
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Khader, Shahbaz Abdul. "System Identification of Active Magnetic Bearing for Commissioning." Thesis, Uppsala universitet, Institutionen för informationsteknologi, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-243630.
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Active magnetic bearing (AMB) is an ideal bearing solution for high performance and energy efficient applications. Proper operation of AMB can be achieved only with advanced feedback control techniques. An identified system model is required for synthesizing high performance model based controllers. System identification is the preferred method for obtaining an accurate model. Therefore, it becomes a prerequisite for the commissioning of AMB. System identification for commissioning poses some challenges and special requirements. In this thesis, system identification of AMB is approached within the context of commissioning. A procedure for identification is developed and applied to experimental data from a prototype AMB system. The identification procedure is based on the so called prediction error method, and it has been performed in the frequency domain. A linear state-space model, along with the required parameters, is successfully identified.
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Nohavec, Donald R. (Donald Richard). "Magnetic bearing design for interferometric mirror-scanning mechanisms." Thesis, Massachusetts Institute of Technology, 1997. http://hdl.handle.net/1721.1/10487.
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Cole, Matthew Owen Thomas. "Fault tolerant control of rotor/magnetic bearing systems." Thesis, University of Bath, 1999. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.285292.
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Patel, Anup. "Pulsed field magnetization of composite superconducting bulks for magnetic bearing applications." Thesis, University of Cambridge, 2013. https://www.repository.cam.ac.uk/handle/1810/256579.
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Permanent magnets are essential components for many devices such as motors, which currently account for 45 % of global electricity consumption, generators and also superconducting magnetic bearings used for applications such as flywheel energy storage. But even the most powerful rare-earth magnets are limited to a remanent field of 1.4 T, whereas superconducting materials such as YBCO in their bulk form have the extraordinary ability to trap magnetic fields an order of magnitude higher, whilst being very compact. This gives them the potential to increase efficiency and allow significant volume and weight reductions for rotating machines despite the need for cooling. A new design of superconducting magnetic bearing has been developed which uses magnetized bulks as the field source, eliminating permanent magnets. Finite element modelling shows that the bulk – bulk design can achieve much higher force densities than existing permanent magnet – bulk designs, giving it potential to be used as a compact magnetic bearing. A system was created to magnetize bulks using a pulsed magnetic field down to 10 K and then measure levitation force. In proving the concept of the proposed design, the highest levitation forces ever reported between two superconducting bulks were measured, including a levitation force of 500 N between a 1.7 T magnetized YBCO bulk and a coaxial $MgB_{2}$ bulk tube. The biggest factor limiting the use of magnetized bulks in applications is magnetizing them in the first place. Using a pulsed magnetic field is most practical but generates excessive heat dissipation leading to a loss of flux in conventional bulk superconductors, which are 100% superconductor. Although multi-pulse techniques help maximise the trapped field, the poor thermal properties of bulk (RE)BCO are a limiting factor. New composite superconducting structures are reported which can overcome these problems by using high thermal conductivity materials, the motivation for which came from finite element modelling of the critical state coupled with heat transfer. In particular, composite structures created by cutting and stacking 12 mm wide (RE)BCO superconducting tape are shown experimentally to have exceptional field trapping ability due to superior thermal and mechanical properties compared to existing bulks. Up to 2 T was trapped in a stack of commercially available tape produced by SuperPower Inc. in the first reported pulsed magnetization of such a stack. Over 7 T was trapped between two stacks using field cooling at 4.2 K, the highest field yet trapped in such a sample.
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Hossain, Mohammad Ahsan. "High temperature, permanent magnet biased, homopolar magnetic bearing actuator." Thesis, Texas A&M University, 2006. http://hdl.handle.net/1969.1/4174.
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The EEC (Electron Energy Corporation) in conjunction with the National Aeronautics and Space Administration is researching the magnetic bearings for an alternative to conventional journal or ball bearings. The purpose of this research was to design and develop a high-temperature (1000úF) hybrid Magnetic Bearing using High Temperature Permanent Magnets (HTPM), developed by the EEC for high performance jet engines at high speeds that supply loads of 500 lbf. Another objective is to design and build a test rig fixture to measure the load capacity of the designed bearing. The permanent magnet bias of the Homopolar radial magnetic bearing reduces the amount of current required for magnetic bearing operation. This reduces the power loss due to the coil current resistance and improves the system efficiency because the magnetic field of the HTPM can suspend the major portion of the static load on bearing. A high temperature radial magnetic bearing was designed via an iterative search employing 3D finite element based electromagnetic field simulations. The bearing was designed to produce 500 lbf of force at 1000úF and the design weight is 48 lbs. The bias flux of the Homopolar radial bearing is produced by EEC HTPM to reduce the related ohmic losses of an electromagnetic circuit significantly. An experimental procedure was developed to measure actual load capacity of the designed bearing at the test rig. All the results obtained from the experiment were compiled and analyzed to determine the relation between bearing force, applied current and temperature.
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Gouws, Rupert. "Condition monitoring of active magnetic bearing systems / R. Gouws." Thesis, North-West University, 2007. http://hdl.handle.net/10394/1305.
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Clements, Joshua Ryan. "The Experimental Testing of an Active Magnetic Bearing/Rotor System Undergoing Base Excitation." Thesis, Virginia Tech, 2000. http://hdl.handle.net/10919/35827.
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Active Magnetic Bearings (AMB) are a relatively recent innovation in bearing technology. Unlike conventional bearings, which rely on mechanical forces originating from fluid films or physical contact to support bearing loads, AMB systems utilize magnetic fields to levitate and support a shaft in an air-gap within the bearing stator. This design has many benefits over conventional bearings. The potential capabilities that AMB systems offer are allowing this new technology to be considered for use in state-of-the-art applications. For example, AMB systems are being considered for use in jet engines, submarine propulsion systems, energy storage flywheels, hybrid electric vehicles and a multitude of high performance space applications. Many of the benefits that AMB systems have over conventional bearings makes them ideal for use in these types of vehicular applications. However, these applications present a greater challenge to the AMB system designer because the AMB-rotor system may be subjected to external vibrations originating from the vehicle's motion and operation. Therefore these AMB systems must be designed to handle the aggregate vibration of both the internal rotor dynamic vibrations and the external vibrations that these applications will produce.
This paper will focus on the effects of direct base excitation to an AMB/rotor system because base excitation is highly possible to occur in vehicular applications. This type of excitation has been known to de-stabilize AMB/rotor systems therefore this aspect of AMB system operation needs to be examined. The goal of this research was to design, build and test a test rig that has the ability to excite an AMB system with large amplitude base excitation. Results obtained from this test rig will be compared to predictions obtained from linear models commonly used for AMB analysis and determine the limits of these models.Master of Science
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Wilson, Brian Christopher David. "Control Designs for Low-Loss Active Magnetic Bearing: Theory and Implementation." Diss., Available online, Georgia Institute of Technology, 2004:, 2004. http://etd.gatech.edu/theses/available/etd-04122004-133631/unrestricted/wilson%5Fbrian%5Fc%5F200405%5Fphd.pdf.
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Thesis (Ph. D.)--Electrical and Computer Engineering, Georgia Institute of Technology, 2004.Habetler, Thomas, Committee Member ; Sadegh Nader, Committee Member ; Taylor David, Committee Member ; Tsiotras Panagiotis, Committee Co-Chair ; Heck-Ferri Bonnie, Committee Co-Chair. Vita. Includes bibliographical references (leaves 319-326).
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Gouws, Rupert. "The development of an axial active magnetic bearing / R. Gouws." Thesis, North-West University, 2004. http://hdl.handle.net/10394/287.
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In this dissertation, the author presents the operation and development of active magnetic
bearings (AMBs) , with specific focus on axial M s . The project objective is the development
of an axial AMB system. The electromagnetic design, inductive sensor design, dSpace
controller model design and actuating amplifier design are aspects discussed in this dissertation.
The physical model constitutes two electromagnets positioned above and beneath a 2 kg steel
disc with an air gap of 3 mm on either side of the disc. The electromagnetic design is done
analytically and verified using Quickfield finite element analysis software.
Inductive sensors are designed to obtain position feedback from the model. These sensors
measure the distance of the air gap between the suspended steel disc and the electromagnets. The
dSpace 1104 controller board and software is used for controlling purposes. This dissertation
describes the system development from the Simulink model to the real-time model, where the
dSpace controller board controls the physical hardware.
The dSpace controller sends out control signals via DIA ports to actuating amplifiers. The
actuating amplifiers then provide a controlling current to the electromagnets. The steel disc is
attracted or released according to the signal provided. The inductive position sensors provide
feedback from the model via the AID port of the dSpace controller to close the control loop.
The control performance of the model is evaluated through steady state analysis (static load test),
dynamic disturbance analysis (downward disturbance test) and step response analyses (amplitude
step response test). The step response analysis provide information about the time-to-peak,
settling time, percentage overshoot, natural frequency, damping ratio, damping constant and
stiffness of the model. The experimental results obtained agree with the expected theoretical
norms.
Future possible projects can be done on the improvement of the sensor (designing a sensor-less
sensor), designing advanced control techniques for the axial AMB model by using the dSpace
DS 1 104 controller and designing an axial AMB model for high speed applications.Thesis (M.Ing.)--North-West University, Potchefstroom Campus, 2004.
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Nel, Johannes Daniel. "The development of a radial active magnetic bearing / J.D. Nel." Thesis, North-West University, 2004. http://hdl.handle.net/10394/542.
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This dissertation presents the development of a radial active magnetic bearing (AMB). With AMBs
the rotor of a machine can be suspended in the air without any direct contact between the stator and
the rotor. This makes it a frictionless bearing and eliminates the need for lubrication. The AMB
system implements a feedback control system to control the position of the rotor.
The aim of this project is to develop a radial AMB with an air gap of 1 mm and a rotation speed of
3000 rpm. Through this project basic knowledge of magnetic suspension is gained and expertise is
established at the Engineering Faculty. The model can be used for further studies and as a
demonstration model to illustrate the concept of AMBs.
The model constitutes one radial AMB and one conventional ball bearing supporting a rigid shaft.
The AMB system constitutes 1) electromagnets, 2) power amplifiers, 3) position sensors and 4) a
control system. Inductive sensors measure the air gap between the shaft and the stator in the vertical
and horizontal axis. The sensor signal is fed back to a controller that provides a control signal to the
power amplifiers. The power amplifiers control the current through the electromagnets that apply a
force on the shaft. The shaft is then suspended in the air. An air pressure turbine is used to propel
the shaft up to 3000 rpm.
A homopolar AMB configuration is implemented using mild steel for the electromagnets. The four
electromagnets used in the system are designed in terms of a required force. Linear power
amplifiers are designed to activate the electromagnets and to eliminate possible noise problems on
the sensors. Inductive position sensors are implemented producing a dc voltage proportional to the
size of the air gap.
dSpace® software is used to implement the controller. A position sensor value is read in through an
analog-to-digital converter channel and subtracted from a reference signal for the position. The
error signal is then the input of the controller. The controller sends a control signal via the digital-to-
analog converter to the power amplifiers. A PID controller is created in sirnulink®. With the aid
of dSpace® software the controller is downloaded onto the dSpace card.
Different tests are performed to characterise the system. The step responses in both axes are
measured and the percentage overshoots and settling times are determined. Impulse disturbance
tests at different speeds are used to calculate the dynamic stiffness and damping of the system.
Stable suspension was achieved with the final AMB system at rotation speeds of 3000 rpm. The
maximum deviation was found to be less than 0.11 mm from the centre position. The settling time
was less than 0.4 s and with no steady state error.
The developed AMB system has a relatively low dynamic stiffness. Future studies can be done to
find the effect that each PID parameter has on the dynamic stiffness. It is recommended that the
controller be implemented on an embedded microcontroller to eliminate the computer and the
dSpace® card.Thesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2005.
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Zhou, F. B. "Transputer-based digital control of an active magnetic bearing system." Thesis, University of Salford, 1997. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.360386.
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Lim, T. M. "The development of a simple magnetic bearing for vibration control." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382421.
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Saket, Fawaz Y. "Controlled escape from trapped contact modes in magnetic bearing systems." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.698961.
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Rotors supported by active magnetic bearings under contact-free levitation have many advantages, such as allowing near frictionless rotation and high rotational speeds. They also provide the designer the capability to achieve increased machine power density. However, magnetic bearings possess limited load capacity and operate under active control. Under certain operational conditions, the load capacity may be exceeded or a transient fault may occur. Touchdown bearings or bushes are required in such systems, from the operational and design points of view, to prevent contact between the rotor and stator laminations causing damage to the system. Rotor/touchdown bearing contact can occur in fault conditions and under external disturbances, even if the magnetic bearings are fully functional. If the rotor makes contact with the touchdown bearings, the ensuing rotor dynamics may result in transient or sustained contact dynamics. These dynamics involve transmitting a range of stresses under distortional strains. Such stresses occur under different contact modes, can be of very short or long duration, and can affect the life span of touchdown bearings. Touchdown bearings thus characterise significant safety and reliability aspects of active magnetic bearing systems. Maximisation of the performance and operational life of magnetic bearing systems dictates the need for minimisation of rotor/touchdown bearing contact. Magnetic bearing forces may have the capability to restore contact-free rotor levitation, though this will require appropriate control strategies to be devised. An understanding of the contact dynamics is required, together with the relationship between these and magnetic bearing control forces. In this thesis, rotor/touchdown bearing contact conditions are identified and investigated dynamically. An active magnetic bearing system with a long flexible rotor is considered. A nonlinear system model is employed, and a speed range covering three of the rotor’s critical frequencies is taken into account. Different types of transient and steady-state contact modes are identified, including non-persistent and persistent trapped contact modes of varying contact force levels and time durations. Design methodology is presented for a force measurement system capable of providing rotor/touchdown bearing contact force related data, based on experimental strain measurement. The system is implemented and a calibration method of assessing magnetic bearing forces based on rotor/touchdown bearing contact is demonstrated. The frequency dependent behaviour of the active magnetic bearing system is considered using evaluated force and phase measurements. Force measurements covering one of the rotor’s critical speeds are experimentally validated using an open-loop control strategy, aimed at attenuating rotor vibration in contact cases. Rotor recovery from a persistent rub contact mode through employing synchronous active magnetic bearing forces is demonstrated and discussed. The range of magnetic bearing control forces capable of contact elimination is also explored for different running speeds. The new control method presented provides insight into potential control methods capable of achieving rotor/touchdown bearing contact recovery utilizing experimental force data in contact conditions. This will contribute towards improving safety and reliability aspects of active magnetic bearing systems, which undergo operational conditions leading to rotor/touchdown bearing contact.
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Girlevicius, Lukas. "Active magnetic bearing driver circuit design featuring current measurement integration." Thesis, Uppsala universitet, Elektricitetslära, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-269215.
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Researchers at Uppsala University are developing a flywheel energy storage device intended to be used in electrical vehicles. Kinetic energy storage technology has potential to make purely electric powertrain both more effective and efficient. While deployment of the third prototype is approaching there has been a request for a more precise and noise-immune circuitry to power active magnetic bearings that hold and stabilise the rotor. A similar circuit designed for powering electromagnets was recently developed at the Uppsala University’s Electricity department and is used as a template in development of the new active magnetic bearing driver circuit. Current measurement integration technique is tested and implemented as a way to increase circuit’s control feedback loop performance. To further boost precision and noise-immunity 0-20 mA current loop signals are adapted as the standard for output signals. Results of this project include a thorough analysis of the electromagnet driver circuit development, implementation of a new current sensing technique including an experimental self-inductance measurement, printed circuit board layout design and a full list of components necessary to power and control two sets of active magnetic bearings consisting of 8 individual electromagnets.
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Frejd, Julia. "Magnetic Mineralogy of Nb-bearing Carbonatites from Oldoinyo Dili (Tanzania)." Thesis, Uppsala universitet, Institutionen för geovetenskaper, 2021. http://urn.kb.se/resolve?urn=urn:nbn:se:uu:diva-445837.
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Niobium (Nb) and Rare Earth Elements (REE’s) have in recent years received considerable attention because of their importance to the modern technical industry, and more specifically the enhanced sustainability that comes with them. The main source for Nb and REE’s on Earth are carbonatites and associated alkaline silicate rocks. This report examines the magnetic properties of rocks from the Oldoinyo Dili carbonatite complex in northern Tanzania. Previous workers have suggested a link between the Fe-bearing mineralogy and the formation of Nb-mineralizations at Oldoinyo Dili. This hypothesis is further examined in this report by combining detailed petrographic observations and withnew measurements of magnetic susceptibility. The aim is to see if any correlation exists between occurrence of Nb-mineralizations and the types of Fe-minerals present at Oldoinyo Dili. Based on the magnetic susceptibility measurements, at least two different species of Fe-minerals arefound in the examined samples. These are characterized by different magnetic trends during heating/cooling and also by their separate Curie temperatures (Tc). In combination with the petrographic observations these minerals are interpreted to be magnetite (Fe2O4) with Tc ~580°C, and a mineral that most likely represents a solid solution between ilmenite (FeTiO3) and hematite (Fe2O3) with Tc ~300°C. Here, no clear link between the type of opaque mineral(s) present and the total Nb content of the carbonatites can be conclusively determined based on the petrography and the magnetic measurements alone. Although the results of this report provide an important first step towards understanding the relationship between Nb-mineralizations and the magnetic mineralogy at Oldoinyo Dili, more detailed analyses of the mineral chemistry is a necessity to fully understand their complex relations and the specific conditions under which they formed.Niob (Nb) och sällsynta jordartsmetaller (REE’s) har på senare år fått stor uppmärksamhet för sin betydelse för den moderna tekniska industrin, och specifikt för den förhöjda hållbarhet som de bidrar med. Den huvudsakliga källan till Nb och REE’s på jorden är karbonatiter och associerade alkalisilikater. Denna rapport undersöker de magnetiska egenskaperna för karbonatit-komplexet Oldoinyo Dili i norra Tanzania. Forskare har tidigare anat att det finns en koppling mellan Fe-bärande mineralogi och bildandet av Nb-mineraliseringar vid Oldoinyo Dili. Denna hypotes undersöks vidare i denna rapport genom att kombinera detaljerade petrografiska observationer med nya mätningar av magnetisk susceptibilitet. Syftet är att undersöka om det finns någon korrelation mellan förekomst av Nb-mineraliseringar och de typer av järnmineral som finns vid Oldoinyo Dili. Baserat på de genomförda magnetiska susceptibilitets-mätningarna så finns det åtminstone två olika sorters järnmineral i de undersökta proverna. De karaktäriseras av olika magnetiska trender vid upphettning/nedkylning och även av sina olika Curietemperaturer (Tc). Kombinerat med petrografiska observationer uttolkas att dessa mineral är magnetit (Fe2O4) med Tc ~580°C, samt en mineral som troligen är en solid solution av ilmenit (FeTiO3) och hematit (Fe2O3) med Tc ~300°C. Det går inte att senågon tydlig koppling mellan förekommande opaka mineral och det totala Nb-innehållet i karbonatiterna med säkerhet enbart utifrån petrografin och de genomförda magnetiska mätningarna. Resultaten av denna rapport utgör ett bra första steg mot att förstå relationen mellan Nb-mineraliseringar och den magnetiska mineralogin för Oldoinyo Dili, men mer detaljerade analyser av mineralkemin är nödvändigt för att till fullo förstå de komplexa förhållanden som råder vid bildning av dessa.
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Schlotter, Michael. "Robust control and contact recovery of rotor/magnetic bearing systems." Thesis, University of Bath, 2007. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.436756.
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Vosloo, Johannes Kristoff. "Rotor delevitation analysis of active magnetic bearing systems / by Kristoff Vosloo." Thesis, North-West University, 2009. http://hdl.handle.net/10394/4917.
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Active magnetic bearing (AMB) systems present an elegant solution to many problems associated with high-speed machinery design and operation. However, AMBs are deficient in that it allows only for contact-free suspension of rotors. Conventional rolling bearings, named backup bearings, are usually installed between the magnetic bearings and the rotor in order to avoid machine damage in the case of suspension failure. Given the critical function fulfilled by backup bearings with respect to system safety, adequacy assessment of these bearings is vital. However, literature on the subject reveals that no established procedures exist in this regard. This need is addressed in the present study by creating computer simulation models which are capable of predicting backup bearing loads during delevitation. This provides a basis on which stress-related failure safety of the backup bearings may be evaluated. The first simulation model which is developed assumes planar dynamics of the rotor and other components. Development of this model mainly serves to resolve computer implementation issues which are relevant to the intended full model. Following development of the first model, a more detailed model is created by major expansion and modification of the developed code. The detailed model accounts for all major effects present during rotor delevitation. These include a rigid rotor model capable of accounting for three-dimensional unconstrained motion, a model of rotor-bearing contact stiffness and a model of the bearing mount stiffness. In order to ensure accurate computer implementation of the models, both are extensively verified by testing against manually obtainable solutions. Following verification, the models are also subjected to a validation process to ascertain the extent to which the models are representative of real-world behaviour. This is done by comparison of model predictions with experimental observations of a practical AMB system.
Many unforeseen problems are encountered during the validation process, hindering detailed validation of the models. Notwithstanding these problems, valuable lessons are learnt which can contribute significantly to improvement of future validation attempts—a greatly lacking aspect of research in the field of rotor delevitation analysis.Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2010.
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Bean, Jaco. "Vibration characterization of an active magnetic bearing supported rotor / J. Bean." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7029.
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The McTronX Research group at the Potchefstroom campus of the North-West University, aims to establish a knowledge base on active magnetic bearing (AMB) systems. Up to date, the group has established a firm knowledge base on various topics related to AMB systems. A recent focus was the design and development of a high speed AMB supported rotor system called the rotor delevitation system (RDS) to analyse rotor drops. During the testing phase of the RDS, the machine exhibited vibrations, of which the origins were unknown.
The research presented in this dissertation sets out to characterize the vibrations of the RDS, which is the group’s first attempt to fulfil the need for characterizing vibrations in an AMB supported rotor. Emphasis is placed on characterizing the natural response of the RDS rotor, stator and integrated system. The research project is defined in terms of four main objectives: rotor and stator characterization, modelling, system characterization and rotor dynamic diagnostics.
A comprehensive literature study introduces the fundamental concepts regarding vibrations of single and multiple degree of freedom systems. These concepts include; natural frequencies, damping, machine vibrations, rotor dynamics and modelling techniques. These modelling techniques are introduced to verify the experimental methodology used to determine the natural frequencies. A critical overview of the literature contextualises the theory with the research investigation.
For the RDS rotor and stator characterization, a modal analysis process also known as the “bump test” is implemented in order to validate the bending natural frequencies of the rotor and stator. A simulation model of the RDS is constructed in the finite element (FE) package DyRoBeS®. The model is verified with a numerical and an analytical model and validated with the measured bending natural frequencies of the RDS rotor. For the system characterization, a number of modal analysis processes are implemented, which validates the rigid body natural frequencies of the RDS. These frequencies are also used to validate the FE simulation. The origins of the synchronous vibration harmonics are verified by formulating and evaluating hypotheses according to different modal analysis processes.
From the RDS rotor modal analysis it was identified that a bending natural frequency of the rotor is situated at approximately 443.33 Hz. This was verified using the FE simulation model. During the system modal analyses, it was identified that only one rigid body natural frequency, situated at approximately 62 Hz, is excited. This frequency increases with the differential gain control parameter of the system up to approximately 140 Hz. After evaluating two hypotheses regarding the origins of the synchronous vibrations harmonics, it was verified that non-circularity of the rotor at the measuring positions is the cause.
Overall the objectives of the study were addressed by characterizing the natural frequencies of the rotor, stator and RDS system. This include the mode forms of the rigid body and bending natural frequencies of the system. The results of the verification and validation methods correlated, which imply these methods are reliable to identify the origins of vibrations in rotor-bearing systems.
The differential gain control parameter of the AMBs control the equivalent damping in the RDS. An increase in this parameter should lead to a decrease in amplitude and frequency of the maximum vibration, and vice versa. However, it was noted that an increase in this parameter caused a linear increase in the rigid body natural frequency. The literature indicates that this effect can only be caused by an increase in system stiffness. It is therefore recommended to evaluate the stiffness of the system as a function of the differential gain control parameter.Thesis (M.Ing. (Mechanical Engineering))--North-West University, Potchefstroom Campus, 2012.
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Fells, Graham. "Digital signal processor based magnetic bearing controllers for energy storage flywheels." Thesis, University of Sussex, 2003. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.424399.
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Perea, Fabián Carlos Antonio. "Physical parameters identification for a prototype of active magnetic bearing system." Master's thesis, Pontificia Universidad Católica del Perú, 2017. http://tesis.pucp.edu.pe/repositorio/handle/123456789/8623.
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In this thesis the algorithms and strategies for active magnetic bearing should be analysed, implemented and simulated in Matlab as well as experimentally tested in the real-time computation system for a prototype of active magnetic bearing. Develop a general method and algorithm identi cation for active magnetic bearings prototype and get real system parameters that allow generate the equation of state
of the system to control its further development. The specific objectives in this Thesis are:
Develop a data acquisition system for the AMBs. Analyse the mathematical model of the system from the real system. Conduct experiments of a physical model for data collection. Develop an identification algorithm for the parameters of the real AMBs. Validate system developed by testing the prototype.Tesis
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Aragón, Ayala Danielo Eduardo. "Optimal control for a prototype of an active magnetic bearing system." Master's thesis, Pontificia Universidad Católica del Perú, 2017. http://tesis.pucp.edu.pe/repositorio/handle/123456789/8675.
Full textAbstract:
First applications of the electromagnetic suspension principle have been in experimental
physics, and suggestions to use this principle for suspending transportation
vehicles for high-speed trains go back to 1937. There are various ways of designing
magnetic suspensions for a contact free support, the magnetic bearing is just one of
them [BCK+09].
Most bearings are used in applications involving rotation. Nowadays, the use of
contact bearings solves problems in the consumer products, industrial machinery, or
transportation equipment (cars, trucks, bicycles, etc). Bearings allow the transmition
of power from a motor to moving parts of a rotating machine [M+92].
For a variety of rotating machines, it would be advantageous to replace the mechanical
bearings for magnetic bearings, which rely on magnetic elds to perform
the same functions of levitation, centering, and thrust control of the rotating parts
as those performed by a mechanical bearing. An advantage of the magnetic bearings
(controlled or not) against purely mechanical is that magnetic bearings are contactless
[BHP12]. As a consequence these properties allow novel constructions, high
speeds with the possibility of active vibration control, operation with no mechanical
wear, less maintenance and therefore lower costs. On the other hand, the complexity
of the active (controlled) and passive (not controlled) magnetic bearings requires
more knowledge from mechanics, electronics and control [LJKA06].
The passive magnetic bearing (PMB) presents low power loss because of the
absence of current, lack of active control ability and low damping sti ness [FM01,
SH08]. On the other hand, active magnetic bearing (AMB) has better control ability
and high sti ness, whereas it su ers from high power loss due to the biased current
[JJYX09].
Scientists of the 1930s began investigating active systems using electromagnets for high-speed ultracentrifuges. However, not controlled magnetic bearings are physically
unstable and controlled systems only provide proper sti ness and damping
through sophisticated controllers and algorithms. This is precisely why, until the
last decade, magnetic bearings did not become a practical alternative to rolling element
bearings. Today, magnetic bearing technology has become viable because of
advances in microprocessing controllers that allow for con dent and robust active
control [CJM04].
Magnetic bearings operate contactlessly and are therefore free of lubricant and
wear. They are largely immune to heat, cold and aggressive substances and are operational
in vacuum. Because of their low energy losses they are suited for applications
with high rotation speeds. The forces act through an air gap, which allows magnetic
suspension through hermetic encapsulations [Bet00].Tesis
27
McCallum, Duncan C. (Duncan Craig). "Dynamic modelling and control of a magnetic bearing-suspended rotor system." Thesis, Massachusetts Institute of Technology, 1988. http://hdl.handle.net/1721.1/14554.
Full text
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Sahinkaya, Alican. "Computational Cost Reduction of Robust Controllers for Active Magnetic Bearing Systems." Cleveland State University / OhioLINK, 2020. http://rave.ohiolink.edu/etdc/view?acc_num=csu1592830264947936.
Full text
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Abulrub, Abdul-Hadi G. "Modelling and control of contact in magnetic bearing/flexible rotor systems." Thesis, University of Bath, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.437436.
Full text
30
Narayanaswamy, Ashwanth. "Study of Catcher Bearings for High Temperature Magnetic Bearing Application." Thesis, 2011. http://hdl.handle.net/1969.1/ETD-TAMU-2011-05-9509.
Full textAbstract:
The Electron Energy Corporation (EEC) along with National Aeronautics and Space Administration (NASA) in collaboration with Vibration Control and Electro mechanics Lab (VCEL), Texas A & M University, College Station, TX are researching on high temperature permanent magnet based magnetic bearings.
The magnetic bearings are made of high temperature resistant permanent magnets (up to 1000 degrees F). A test rig has been developed to test these magnetic bearings. The test rig mainly consists of two radial bearings, one axial thrust bearing and two catcher bearings. The test rig that the catcher bearing is inserted in is the first ultra-high temperature rig with permanent magnet biased magnetic bearings and motor. The magnetic bearings are permanent magnet based which is a novel concept. The Graphalloy bearings represent a new approach for ultra-high temperature backup bearing applications.
One of the main objectives of this research is to insure the mechanical and electrical integrity for all components of the test rig. Some assemblies and accessories required for the whole assembly need to be designed. The assembly methods need to be designed. The preliminary tests for coefficient of friction, Young's modulus and thermal expansion characteristics for catcher bearing material need to be done. A dynamic model needs to be designed for studying and simulating the rotor drop of the shaft onto the catcher bearing using a finite element approach in MATLAB.
The assembly of the test rig was completed successfully by developing assembly fixtures and assembly methods. The components of the test rig were tested before assembly. Other necessary systems like Sensor holder system, Graphalloy press fit system were designed, fabricated and tested. The catcher bearing material (Graphalloy) was tested for coefficient of friction and Young's modulus at room and high temperatures. The rotor drop was simulated by deriving a dynamic model, to study the effect of system parameters like clearance, coefficient of friction, negative stiffness, initial spin speed on system behavior.
Increasing the friction increases the backward whirl and decreases the rotor stoppage time. Increasing the clearance reduces the stoppage time and increases the peak bearing force. Increasing the initial spin speed increases the rotor stoppage time. The maximum stress encountered for as built conditions is more than allowable limits.
31
Lee, Mean Shian, and 李孟賢. "A Single Axis Magnetic Bearing." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/90785644502318181156.
Full text
32
Chiao, Wen-Shan, and 趙文山. "The Digital Magnetic Bearing System." Thesis, 1999. http://ndltd.ncl.edu.tw/handle/43354780574294237072.
Full textAbstract:
碩士中正理工學院
電機工程研究所
87
The aims of this thesis are to investigate the characteristics of rotating spindle suspended by magnetic bearings and to design the digital circuits hardware, analog circuits hardware and digital controllers. The dynamic characteristics of magnetic bearing system are suffered by many problems, such as nonlinearities, unbalances, parameter variations, and external disturbances. In order to balance the magnetic suspended bearing, position sensors and Hall current sensors are used in a PC-based system to sense the bearing’s position and the current of control coils. The position and current signals are analog types. These analog signals will be processed by A/D converters and digital PID controllers. The PC-based system then uses sliding mode concept to produce ON/OFF signals. The ON/OFF signals drive IGBTs and keep the magnetic suspended bearings under balancing condition.
33
Liao, Xin-Wei, and 廖信瑋. "Radial passive magnetic bearing in ball bearings supporting rotor system applications." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/yvcpxc.
Full textAbstract:
碩士中原大學
機械工程研究所
102
Nowadays, magnetic systems have been applied in the industry systems widely due to the frictionless property of magnetic systems. Magnetic systems have two kinds: passive and active magnetic systems. Active magnetic systems use electronic magnet to control the subjects, such as rotors or platforms, by controlling the current to adjust the size of magnetic force. The advantage is the system stability can be confirm via tuning the magnetic force by the feedback signals, but the disadvantage is the magnetic system need additional control system and will consume the power. Passive magnetic systems use the permanent magnets to produce magnetic force. The advantage is it can be used a widely range, but the disadvantage is its magnetic force can’t be controlled, need to calculate the magnetic force. A passive magnetic bearing and a ball bearing are combined to form a hybrid bearing system in this paper. The passive magnetic bearing is used to increase the maximum radial load capacity and reduce the ball bearing load then promote the bearing life. The reasons we chosen a passive magnetic bearing are that the passive magnetic bearing system has no friction, does not need additional control, widely using environment and cheaper than the active magnetic bearing. The coordinate ball bearing is a deep groove ball bearing. The deep groove ball bearings are one of the most widely used ball bearings. Because the load capacity and life of the ball bearing are both lower than the steel ball bearing. This paper used a deep groove ball bearing with the inner radius is 10mm, the outer radius is 19mm, and the thickness is 10mm to be a test bearing. The experiment result showed that the proposed hybrid bearing can promote the bearing life. First, we calculated the radial force and axial force for the supporting system to determine the system specifications and capacity and the need of the supporting system. Then analyzed the relationship of forces and positions of the passive magnetic bearing according to the formula of the permanent magnet and to simulate the magnetic circuit with JMAG to choose a suitable set of permanent magnets to form a result with maximum radial force and minimum axial force. Finally, the passive magnetic bearing and the deep groove ball bearing are combined to test and confirm with the simulation results.
34
Tsai, Yu-Hue, and 蔡宇輝. "Development of an Axial Magnetic Bearing for Self-Bearing Motors." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/89vq23.
Full textAbstract:
碩士國立臺北科技大學
電機工程系所
100
Thrust actuators are necessary for magnetically levitated rotating machines to provide axial force for rotor balancing. Conventional designs generally consist of two electromagnetic units and iron plate, but they produce very small radial force and the thrust density is low. Recent thrust actuator designs often integrate permanent magnets into the stator core or rotor and mix the excitant windings to one set to enhance the thrust density and easier control . However, considerable radial force may present with using permanent magnetic if not designed carefully. The radial force produced by the thrust actuator is not desirable since it becomes a burden to radial actuator control. And it may shutdown the whole system. This paper presents a new thrust actuator design for magnetic bearings. The actuator can produce high thrust but low radial attraction force. The actuator force characteristics are analyzed using finite-element analysis. Experimental verifications are also performed.
35
Qiu, Guo Ji, and 邱國基. "The study of magnetic coupling and passive magnetic bearing." Thesis, 1994. http://ndltd.ncl.edu.tw/handle/15454741339254243315.
Full text
36
Chuang, Kun-Fu, and 莊坤富. "Analysis, Design of Passive Magnetic Bearing." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/06917012009554525246.
Full text
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Ji, Jin-Chen. "Nonlinear dynamics of magnetic bearing systems." Thesis, 2006. http://hdl.handle.net/2440/63568.
Full textAbstract:
The aim of the work outlined in this thesis was to gain a deep insight into the effects of nonlinearities of magnetic bearings and the influence of time delays occurring in the feedback path control on their dynamic behaviour and performance. Emphasis was on stability analysis, bifurcation control, determination of stable operating conditions, prediction of bearing performance, and on aspects of nonlinear dynamic behaviour including bifurcations, coexistance of multiple solutions and complicated motions ... The present thesis comprises 12 papers which were recently published in seven international journals.Thesis (Ph.D.) - University of Adelaide, School of Mechanical Engineering, 2006
38
Somad, Fitriah. "System identification and control of magnetic bearing systems." Thesis, 2007. https://vuir.vu.edu.au/1413/.
Full textAbstract:
This thesis presents investigations aimed at obtaining a system model for the stabilisation of an Active Magnetic Bearing (AMB) System. Furthermore, the study reported here set out to design both conventional and advanced controllers based on the system model. This research report demonstrates that the literature on AMBs shows that AMBs are making their mark in the industry; they are increasingly being used in applications including jet engines, compressors, pumps and flywheel systems. In this study, it has also been observed that the basic design of AMBs is an arrangement of electromagnets placed equidistant in a ring round a rotor. The point of departure for this study is that AMBs are highly nonlinear and inherently unstable. Hence, the need for an automatic control to keep the system stabilized. The first step of the research was to determine the transfer function of the MBC 500 magnetic bearing system both analytically and experimentally. An analytical model has been derived based on principle of physics. As the AMB system under analysis is inherently unstable, it was necessary to identify the model using a closed-loop system identification. Frequency response data has been collected using the two-step closed loop system identification. As there are resonant modes in the MBC 500 magnetic bearing system, the system identification approach has identified the corresponding resonant frequencies. Subsequent to obtaining the model, a conventional controller was designed to stabilise the AMB system. Two notch filters were designed to deal with the magnitude and phase fluctuations around the two dominant resonant frequencies. The designed conventional controller and notch filters have been implemented using MATLAB, SIMULINK and dSPACE DS1102 digital signal processing (DSP) card. Both the step response and robustness tests have demonstrated the effectiveness of the conventional controller and notch filters designed. A significant conclusion has been drawn when designing the conventional controller. It was found that a controller that had a large positive phase angle had a negative effect on the system. This finding was very significant because it restricted the controller specifications and yielded an optimum lead angle for the conventional controller. The advanced PD-like Fuzzy Logic Controller (FLC) has also been designed for AMB system stabilisation. The designed FLC can deal with the magnitude and phase fluctuations around resonant frequencies without using notch filters. The performance of the designed FLC has been evaluated via simulation. Simulation results show that the FLC designed leads to a reliable system performance. Comparison studies of the FLC performances with two different sets of rules, two different inference methods, different membership functions, different t-norm and s-norm operations, and different defuzzification were investigated. To further improve system performance, scaling factors were tuned. Again, simulations showed highly promising results. Comparative studies between the conventional and advanced fuzzy control methods were also carried out. Advantages and disadvantages of both approaches have been summarised. The thesis has also suggested further research work in the control of AMBs.
39
Hong, Jai-Sheng, and 洪再生. "Identification of a nonlinear magnetic bearing system." Thesis, 1995. http://ndltd.ncl.edu.tw/handle/71379821117203012700.
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40
Nguyen, Van Sum, and 阮文森(Van Sum Nguyen). "Nonlinear Control for Active Magnetic Bearing System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/4g2x7g.
Full textAbstract:
博士大葉大學
電機工程學系
103
Recently, the studies on the active magnetic bearing (AMB) has become more and more popular and practical. In some special environment, the magnetic bearing plays an important role to sole many problems such as noise, friction, and vibration for the conventional mechanical bearing. Nevertheless, the control of the AMB is another problem to solve. The magnetic force has a high nonlinear relation with the air gap. In practice, no precise mathematical model can be established because the rotor displacement in an AMB system is inherently unstable, and the relationship between the current and electromagnetic force is highly nonlinear. This thesis proposes an intelligent control method for positioning an AMB system, using the emerging approaches of the Fuzzy Logic Controller (FLC) and online trained adaptive neural network controller (NNC), and self-tuning fuzzy Proportional Integral Derivative (PID) controller for current-control loop. An AMB system supports a rotating shaft, without physical contact, using electromagnetic forces. In the proposed controller system, an FLC was first designed to identify the parameters of the AMB system. NNC uses an initial training data with two inputs signal (the error and derivative of the error), and one output signal obtained from the FLC. Finally, an NNC with online training features was designed using an S-function in Matlab software to achieve improved performance. The FLC and self-tuning fuzzy PID controller have been verified on a prototype AMB system. An experimental AMB system is implemented by real time windows target (RTWT) in Matlab environment. The system response proves a low overshoot, an exhibited zero steady-state error, and a reducing rotor displacement of an AMB system. Keywords: Active magnetic bearing (AMB), fuzzy logic controller (FLC), neural network controller (NNC), self-tuning fuzzy PID controller.
41
Chiang, Chia-Han, and 江佳翰. "Research of The Horizontal Magnetic Bearing System." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/48450860282028816468.
Full textAbstract:
碩士國立雲林科技大學
電機工程系
102
ABSTRACT In this thesis, we establish horizontal magnetic bearing flexible rotor control system. The rotor of machine tools generate vibration at work. The rotor of magnetic bearing has the characteristic of working without any contact. Hence, it has some advantages such as noiseless, no need for lubricants etc. The electromagnetic force is controlled by the coil current which realizes the height control for magnetic bearing system. The first controller design is PID controller which is the most common used in the industry. The second controller design is the PID controller with immune theory which used immune algorithms to overcome the lumped bounded uncertainty on-line. Hence, the response is better than traditional PID controller. The third controller is sliding mode controller which is stable quickly. However, the sliding mode controller has the chattering phenomenon. The fourth controller design is the sliding mode controller with immune theory which reduces chattering and has good performances. The microprocessor is used in controller realization which is cheaper than the DSP controller board. The motor driver circuit, electromagnetic control circuit and infrared ray distance sensor are built in the closed loop control system.
42
LI, HONG-WEI, and 李鴻偉. "Magnetic Bearing System with Wireless Remote Control." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/59wp9a.
Full textAbstract:
碩士國立雲林科技大學
電機工程系
106
This thesis proposed a complementary sliding mode control and neural network observer for active magnetic bearing system to control the height. The intersection of two different sliding surfaces in complementary sliding mode control makes the system to have good performance. The neural network observer improves the chatting magnitude in the system. This thesis also proposed a wireless drive control construction based on LoRa technology which the Microsoft C# language is used to design a human interface for modifying parameters and receiving data. This construction can be used in general industrial application to reduce the human resources.
43
Lin, Jin-Peng, and 林金鵬. "Development of a PMAC Self-bearing Motor and Axial Magnetic Bearing Integration System." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/znqfu3.
Full textAbstract:
碩士國立臺北科技大學
電機工程系研究所
100
In the magnetic levitation system, to realize non-co ntact magnetic suspension, the rotor must be magnetically stabilized in five degrees of freedom. Since the motor is responsible for generating torque in conventional magnetic levitation system, it needs the additional two radial magnetic bearing and one thrust magnetic bearing to realize non-contact magnetic suspension. Self-bearing motor is a result of the integration of a radial magnetic bearing and a motor, which generate motor torque and radial force simultaneously. This essay proposed a three-axis-controlled bearingless motor system which consists of a bearingless motor, a thrust magnetic bearing and a passive magnetic bearing, although less stability than five-DOF bearingless motor system, it still have the advantage of compactness, easily control and low cost. After the three-DOF bearingless motor system is analyzed by finite element analysis software, the passive magnetic bearing is designed, the system component location is analyzed and the force of system is also analyzed, and finally established the prototype system and verified the performance by experiment.
44
Gandhi, Varun R. "High Temperature, Permanent Magnet Biased Magnetic Bearings." 2009. http://hdl.handle.net/1969.1/ETD-TAMU-2009-05-276.
Full textAbstract:
The Electron Energy Corporation (EEC) along with the National Aeronautics and
Space Administration (NASA) is researching magnetic bearings. The purpose of this
research was to design and develop a high-temperature (1000�F) magnetic bearing
system using High Temperature Permanent Magnets (HTPM), developed by the EEC.
The entire system consisted of two radial bearings, one thrust bearing, one motor and 2
sets of catcher bearings.
This high temperature magnetic bearing system will be used in high
performance, high speed and high temperature applications like space vehicles, jet
engines and deep sea equipment. The bearing system had a target design to carry a load
equal to 500 lb-f (2225N). Another objective was to design and build a test rig fixture to
measure the load capacity of the designed high temperature radial magnetic bearing
(HTRMB) called Radial Bearing Force Test Rig (RBFTR).
A novel feature of this high temperature magnetic bearing is its homopolar
construction which incorporates state of the art high temperature, 1000 �F, permanent
magnets. A second feature is its fault tolerance capability which provides the desired
control forces even if half the coils have failed. The permanent magnet bias of the radial magnetic bearing reduces the amount of
current required for magnetic bearing operation. This reduces the power loss due to the
coil current resistance and also increases the system efficiency because magnetic field of
the HTPM is used to take up the major portion of the static load on the bearing. The bias
flux of the homopolar radial bearing is produced by the EEC HTPM to reduce the related
ohmic losses of an electromagnetic circuit significantly.
An experimental procedure was developed using the Radial Bearing Force Test
Rig (RBTFR) to measure actual load capacity of the designed bearing at the test rig. All
the results obtained from the experiment were compiled and analyzed to determine the
relation between bearing force, applied current and temperature.
45
Yuliane, Aindri, and 游莉安. "Dynamic Simulation of Active Magnetic Bearing Supported Rotor Compressor During Drop on Touchdown Bearings." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/74qq37.
Full textAbstract:
碩士國立勤益科技大學
冷凍空調系
106
The advantages offered by Active Magnetic Bearings (AMBs) make that bearing widely used in many applications, for example is centrifugal compressor. One of the advantages of magnetic bearing is no need lubrication oil. Eliminating the use of oil as a lubricant, not only reduces system complexity and cost, but also can affect to the improvement of compressor efficiency and reliability. However, the system that used magnetic bearing must be equipped with touchdown (auxiliary) bearings to prevent the damages of impeller and motor in case of system failure or commonly called as rotor drop event. When the drop event occurs, active magnetic bearing can not support the rotor stably, touchdown bearings will be a backup for active magnetic bearings to support the rotor during drop down event. The properly designed touchdown bearing system is necessary to protect the active magnetic bearings assembly and other critical machine components from direct contact with the rotor during in a loss of AMB power events. The failure of AMBs generates a non-linear behavior or interaction of the rotor with touchdown bearings. Therefore, this study presents the dynamic simulation of the rotor compressor during drop event using a finite element approach in MATLAB software. A finite element based 2-DOF flexible rotor model is used to indicate the rotor behavior. The rotor model also considers the contact force between shaft-inner race and ball bearing force based on Un-lubricated Hertzian contact models. In this study, the effect of rotor speed will be examined to predict and analyze the rotor orbit, rotor response and contact force. Moreover, in this study will present the effect of the damping and stiffness support as an improvement to the original design. MATLAB App Designer also has been developed in this study as a user interface to show the results of touchdown bearing simulation directly for easier interpretations of simulation results and observation of changeable parameters.
46
Somad, Fitriah. "System identification and control of magnetic bearing systems." 2007. http://eprints.vu.edu.au/1413/1/somad.pdf.
Full textAbstract:
This thesis presents investigations aimed at obtaining a system model for the stabilisation of an Active Magnetic Bearing (AMB) System. Furthermore, the study reported here set out to design both conventional and advanced controllers based on the system model. This research report demonstrates that the literature on AMBs shows that AMBs are making their mark in the industry; they are increasingly being used in applications including jet engines, compressors, pumps and flywheel systems. In this study, it has also been observed that the basic design of AMBs is an arrangement of electromagnets placed equidistant in a ring round a rotor. The point of departure for this study is that AMBs are highly nonlinear and inherently unstable. Hence, the need for an automatic control to keep the system stabilized. The first step of the research was to determine the transfer function of the MBC 500 magnetic bearing system both analytically and experimentally. An analytical model has been derived based on principle of physics. As the AMB system under analysis is inherently unstable, it was necessary to identify the model using a closed-loop system identification. Frequency response data has been collected using the two-step closed loop system identification. As there are resonant modes in the MBC 500 magnetic bearing system, the system identification approach has identified the corresponding resonant frequencies. Subsequent to obtaining the model, a conventional controller was designed to stabilise the AMB system. Two notch filters were designed to deal with the magnitude and phase fluctuations around the two dominant resonant frequencies. The designed conventional controller and notch filters have been implemented using MATLAB, SIMULINK and dSPACE DS1102 digital signal processing (DSP) card. Both the step response and robustness tests have demonstrated the effectiveness of the conventional controller and notch filters designed. A significant conclusion has been drawn when designing the conventional controller. It was found that a controller that had a large positive phase angle had a negative effect on the system. This finding was very significant because it restricted the controller specifications and yielded an optimum lead angle for the conventional controller. The advanced PD-like Fuzzy Logic Controller (FLC) has also been designed for AMB system stabilisation. The designed FLC can deal with the magnitude and phase fluctuations around resonant frequencies without using notch filters. The performance of the designed FLC has been evaluated via simulation. Simulation results show that the FLC designed leads to a reliable system performance. Comparison studies of the FLC performances with two different sets of rules, two different inference methods, different membership functions, different t-norm and s-norm operations, and different defuzzification were investigated. To further improve system performance, scaling factors were tuned. Again, simulations showed highly promising results. Comparative studies between the conventional and advanced fuzzy control methods were also carried out. Advantages and disadvantages of both approaches have been summarised. The thesis has also suggested further research work in the control of AMBs.
47
Li, Guoxin. "Robust stabilization of rotor-active magnetic bearing systems/." 2007. http://wwwlib.umi.com/dissertations/fullcit/3248091.
Full text
48
HUNG, JIAN-JIE, and 洪健杰. "Intelligent Backstepping Control in Vertical Magnetic Bearing System." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/uk7m3j.
Full textAbstract:
碩士國立雲林科技大學
電機工程系
105
In recent decades, maglev technology has already applied to different products. The most famous maglev train uses electric power to instead of traditional fuel for as environmenatal protection. The other maglev technology is applied to industrial bearing which called magnetic bearing. Maglev bearing rotates in air for a long time without lubricant. The thesis utilizes system dynamic equation to design backstepping controller and uses estimator to estimate system uncertainty of adaptive, dynamic sliding mode and neural network to improve sign function of the maximum system uncertainty. We proposed four nonlinear controllers design of adaptive backstepping control, dynamic sliding mode backstepping control, neural network backstepping control and radial basis neural network backstepping control to guarantee the stability by Lyapunov stability theory. In the controller realization, we used dSPACE1104DSP control card to shorten the research time. The control card develops completely which includes accesses A/D and D/A data and prints documents easily. The DS1104’s calculations ability, input/output channel, Simulink Real-Time Interface(RTI) software, and human-computer interaction software can verify control strategy.
49
黃松鶴. "The Nonlinear Control of a Magnetic Bearing System." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/34505214634570471590.
Full textAbstract:
碩士國立中央大學
機械工程研究所
89
The magnetic bearing system is a nonlinear system. In this thesis, we discuss four different controllers. The first controller is PID controller. Its advantages are easily implemented and simple calculated. It is the best-known controller applied in industrial control processes. The second controller is fuzzy gain scheduling of PID controller. The human expertise on PID gain scheduling can be represented in fuzzy rules and it improves the performance of traditional PID controller with fixed parameters. The third controller is sliding mode controller. Before we use the sliding controller, we should do the system identification. And then we use the model from ID to design the sliding controller. The system is completely insensitive to parametric uncertainty and external disturbances when we use the sliding mode controller. The last one is the adaptive feedforward controller. When the principal axis of inertia is not coincident with the axis geometry it will cause an unbalance mass. The adaptive feedforward controller could reduce the unbalance force caused by an unbalance mass.
50
YAN, MING XIAN, and 顏銘憲. "Magnetic Bearing Design with Single-axis Active Control." Thesis, 2003. http://ndltd.ncl.edu.tw/handle/20166516945558048233.
Full textAbstract:
碩士國立臺灣大學
電機工程學研究所
91
Internal manufacturer specializing in computer fans have developed the technology of Magnetic Levitation Motor Fan and took a patent on the design for the time being. The principle of magnetic-levitated train is led into the structure of motor. The weight of impeller rotor is attractive by the magnet plate, so that the tail top of the shaft is without load and contacted with the cap fixed on the bottom of the metal tube, which results in keeping the motor rotating evenly at a fixed point and a consistent distance from inner surface of the bearing. As a result of passive Magnetic Levitation design of the system, the influence of friction on noise and speed of rotation will be reduced greatly. Though there is still a contact point between the tail top of the shaft and the cap. The system performance will be improved if we can get over the contact point. In order to achieve suspension and reduce the cost and volume of the bearing system, the magnetic levitation design of single degree of freedom is selected to the first architecture in this thesis. In another word, the combination of active and passive control is adopted. We control the magnetism of the electromagnet to keep the suspension of the shaft in the axial direction, and use the passive bearing composed of two sets of permanent magnets to keep the balance of the shaft in the radial direction. After the test, the first design could be axial suspension. But, it can’t be placed in any mounted position. Therefore we follow up the first design with a new design of small architecture, which the volume and weight of the shaft is reduced and the balance force of the shaft in the radial direction is enhanced. Through the results of the simulation, the defects of the first design will be improved.