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1
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.
Full textAbstract:
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.
2
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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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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4
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.
Full textAbstract:
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
5
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.
Full textAbstract:
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
6
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
7
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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8
Vogel, Deon Edward. "Embedded controller for a fully suspended active magnetic bearing system / D.E. Vogel." Thesis, North-West University, 2006. http://hdl.handle.net/10394/1121.
Full textAbstract:
The industrial application of active magnetic bearings is expanding. This expansion is a driving
force in the integration of AMBs. The Magnetic Bearing Modelling and Control (MBMC) research
group in the School of Electrical, Electronic and Computer Engineering, North-West University is
accordingly compelled to expand their research to the application of embedded control systems.
The aim of this study is to develop an embedded controller for an active magnetic bearing in order
to establish a DSP platform for future research in embedded control systems.
The embedded controller developed during this study is required to be capable of actively controlling
a spindle with a rotational speed of 60 000 rpm. It is further required that the embedded
controller is capable of stand-alone operation, scalable in terms of the number of axes controlled
and flexible in terms of the control algorithm implementation.
A TMS320F2812 DSP is selected for its processing speed, on-chip peripherals and available development
tools such as the eZdsp® TMS320F2812 DSP Starter Kit, VisSim® Embedded Controls
Developer and Code Composer Studio®. The interface of the embedded controller is designed
for an existing double radial AMB model, which allows for the performance of the embedded
controller to be compared to the existing PC-based controller.
The AMB system exhibits a slightly higher second order equivalent stiffness and damping when
using the embedded controller as opposed to the existing PC-based controller. The AMB system
is also slightly less sensitive when using the embedded controller.
This embedded controller establishes a DSP platform which can be used for further research
into embedded control systems and advanced control algorithms. The knowledge gained and
controller developed for this study serves as essential stepping stones towards the ultimate goal of
AMB integration through the progression from a DSP to an FPGA and eventually an ASIC.Thesis (M. Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2006.
9
Combrinck, Angelique. "Adaptive control of an active magnetic bearing flywheel system using neural networks / Angelique Combrinck." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4457.
Full textAbstract:
The School of Electrical, Electronic and Computer Engineering at the North-West University in
Potchefstroom has established an active magnetic bearing (AMB) research group called McTronX.
This group provides extensive knowledge and experience in the theory and application of AMBs. By
making use of the expertise contained within McTronX and the rest of the control engineering
community, an adaptive controller for an AMB flywheel system is implemented.
The adaptive controller is faced with many challenges because AMB systems are multivariable,
nonlinear, dynamic and inherently unstable systems. It is no wonder that existing AMB models are
poor approximations of reality. This modelling problem is avoided because the adaptive controller is
based on an indirect adaptive control law. Online system identification is performed by a neural
network to obtain a better model of the AMB flywheel system. More specifically, a nonlinear autoregressive
with exogenous inputs (NARX) neural network is implemented as an online observer.
Changes in the AMB flywheel system’s environment also add uncertainty to the control problem. The
adaptive controller adjusts to these changes as opposed to a robust controller which operates despite
the changes. Making use of reinforcement learning because no online training data can be obtained, an
adaptive critic model is applied. The adaptive controller consists of three neural networks: a critic, an
actor and an observer. It is called an observer-based adaptive critic neural controller (ACNC).
Genetic algorithms are used as global optimization tools to obtain values for the parameters of the
observer, critic and actor. These parameters include the number of neurons and the learning rate for
each neural network. Since the observer uses a different error signal than the actor and critic, its
parameters are optimized separately. When the actor and critic parameters are optimized by
minimizing the tracking error, the observer parameters are kept constant.
The chosen adaptive control design boasts analytical proofs of stability using Lyapunov stability
analysis methods. These proofs clearly confirm that the design ensures stable simultaneous
identification and tracking of the AMB flywheel system. Performance verification is achieved by step
response, robustness and stability analysis. The final adaptive control system remains stable in the
presence of severe cross-coupling effects whereas the original decentralized PD control system
destabilizes. This study provides the justification for further research into adaptive control using
artificial intelligence techniques as applied to the AMB flywheel system.Thesis (M.Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2011.
10
Van, Rensburg Jacques Jansen. "An integrated controller for an active magnetic bearing system / by Jacques Jansen van Rensburg." Thesis, North-West University, 2007. http://hdl.handle.net/10394/2306.
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11
Ranft, Eugén Otto. "The development of a flexible rotor active magnetic bearing system / by Eugén O. Ranft." Thesis, North-West University, 2005. http://hdl.handle.net/10394/892.
Full textAbstract:
The School of Electrical and Electronic Engineering at the North-West University is in the
process of developing an Active Magnetic Bearing (AMB) research laboratory. The aim is to
establish a knowledge base on AMBs in support of industries that make use of this
environmentally friendly technology. AMB technology is seen as one of the technology drivers
for the Pebble Bed Modular Reactor (PBMR) currently in development in South Africa and is
predicted to become largely conventional in this application.
In the process of developing an AMB laboratory some basic models are constructed to establish
infrastructure for research investigations. The aim of this project is to develop a flexible rotor
double radial AMB system. The system comprises a laminated heteropolar magnetic actuator,
eddy-current position sensors, switch-mode power amplifiers and a digital controller. Emphasis
is placed on stable suspension of a flexible rotor through the first three critical frequencies. This
project also caters for future work on high speed losses in AM6 systems.
A design process comprising aspects of modelling and analysis is developed, implemented and
verified for a flexible rotor AMB system. The design commences with a system specification
followed by an iterative process comprising electromagnetic design, detailed system modelling
and rotordynamic analysis, and is concluded with design implementation and verification.
The system design includes two interchangeable rotors; a flexible rotor for rotordynamic
analyses and a rigid rotor for high speed loss analyses. The flexible rotor system is specified to
experience the first three critical frequencies up to an operating speed of 10,000 rpm. The rigid
rotor maximum operating speed is specified as 30,000 rpm. Rotor stability at critical frequencies
places specific constraints on the equivalent stiffness and damping parameters of the AMB.
An iterative design process is then initiated by an analytical electromagnetic design of the radial
AMBs conducted in MathCAD® The magnetic actuator utilizes a 0.6 mm air gap and has a
maximum load capacity of 500 N. A force slew rate specification of 5x10~N /s is obtained from
the system's equivalent stiffness (500 N/mm) and damping (2.5 N.s/mm) parameters resulting in
a 3 kVA power amplifier requirement. These parameters are used in the detailed MATLAB®
modelling of the system. Stiffness and damping parameters as well as system dynamic
response are verified and used to design a flexible rotor. The magnetic bearing locations,
displacement sensor locations and rotordynamic response are verified using finite element
methods. The design of the rotor stands central to the iterative design process since it impacts
on the forces experienced by the AMBs as well as the critical frequencies of the AMB system.
The most important outcome of the iterative design process is a dimensioned electromagnetic
configuration and two rotor designs. The flexible rotor spans 500 mm and weighs 7.72 kg
whereas the rigid rotor has the same length and weighs 12.5 kg. A centre mass on the flexible
rotor lowers the first three critical frequencies to below the maximum operating speed.
A 3 kVA (300 V, 10 A) switch-mode, current controlled power amplifier (PA) is developed in-house
as part of the outcome of the study. The topology used is a two-quadrant controlled
H-bridge, switched at 100 kHz and controlled in current-mode. The design is thoroughly verified
through a process of prototyping and includes aspects of electromagnetic compatibility and
protection in terms of over-current and temperature. The PA exhibits a 6 kHz bandwidth and
linear characteristics and plays a critical role in the AMB system performance.
The AMB controller is realised with a dSPACE® real-time development tool (DS1104), located
inside a personal computer (PC). The rotational speed is monitored with an optical speed
sensor while the shaft is propelled via an air turbine unit.
Once constructed the actual AMB stiffness and damping parameters as well as its dynamic
response are obtained. Discrepancies between the analytically predicted, simulated and
experimentally obtained results are addressed and clarified. The sensitivity of the system to
parameter changes is obtained as a measure of marginal stability. The rotordynamic response
is characterised by measuring the rotor displacement at pre-defined locations as the rotor
traverses the critical frequencies. These results show good correlation with the predicted
rotordynamics.
This study emphasises the importance of extensive modelling and analyses in the design of
AMB systems to guarantee the required performance of the end product in terms of its dynamic
performance and stability. The most important outcome of this project is a working high speed
AMB model complete with integrated control. The system is versatile and allows for a variety of
investigations including advanced control investigations and high speed magnetic bearing loss
analyses. This project uniquely contributes to the research currently underway in the field of
AMBs in the School of Electrical and Electronic Engineering.Thesis (M. Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2005.
12
Steyn, Stephanus Jacobus Marais. "Multivariable H control for an active magnetic bearing flywheel system / Stephanus Jacobus Marais Steyn." Thesis, North-West University, 2010. http://hdl.handle.net/10394/4939.
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Objectives: The aims of this pilot study were to quantify respiratory and potential dermal exposure of nail
technicians to acetone, formaldehyde, ethyl methacrylate, methyl methacrylate, toluene and xylene. Fifteen female
nail technicians, working in different salons participated in this study. Products used for nail treatments differed
between salons. Most salons used acrylate based nail products whereas others used UV–gel products exclusively.
Methods: The participants were divided into two groups, those who used acrylate– and those who used UV–gel
products exclusively. Eight hour personal respiration exposure to acetone, formaldehyde, ethyl methacrylate,
methyl methacrylate, toluene and xylene were determined. The concentration of airborne volatile organic
compounds in the salons was also determined with the use of a direct reading instrument (EntryRAE). Potential
dermal exposure to the above mentioned solvents (excluding formaldehyde) was determined with the use of
charcoal pads (surrogate skin method). During respiratory and dermal sampling, observations were made regarding
work practices and control measures used in the salons. Results: It was found that the eight hour time weighed
average exposure is well below the recommended occupational exposure limits of the individual chemicals and
showed no additive effect. The highest mean respiratory exposures in both groups were acetone (27.22 mg/m3 and
28.36 mg/m3). EntryRAE results showed peak periods of exposure to volatile organic compounds during the day
(322.16 ppm) that were much higher than the average eight hour exposure (0.21 ppm). The two groups’ exposure
levels were compared to determine if there is a significant difference between the exposures levels but no
statistically significant difference was found. The dermal exposures on hand and neck to acetone, ethyl
methacrylate and methyl methacrylate showed strong significant correlations to the concordant chemical’s
respiratory exposures. Correlations between air and dermal exposure was calculated once more after adjusting
dermal exposure but the findings indicated only one statistically significant correlation of 0.42 in the case of ethyl
methacrylate. Conclusion: Nail technicians are not at immediate health risk as the exposure in nail salons are well
below recommended occupational exposure limits. However the unknown effects of chronic low level exposure to
solvents and the large number of previous studies that reported increased health risks in nail technicians must also
be considered. The use of methyl methacrylate in nail products sold in South Africa is also worrying as methyl
methacrylate is banned by the FDA in the US due to its skin sensitisation potential that may lead to allergic contact
dermatitis. The methods used to determine potential dermal exposure as well as adjusted dermal exposure remains
problematic. This is due to the high percentage of adjusted dermal exposure values that had to be estimated and the
fact that the activated charcoal pads have a higher absorption potential than human skin. Both methods must be
improved to increase accuracy of results. Observations and EntryRAE results demonstrated the irregular nature of
a nail technician’s work shift as well tasks performed from day to day. This complicates gathering data that is
representative of a nail technicians eight hour exposure. Therefore to further improve accuracy of results, sampling
should in future be task specific. Conventional ball–bearings in rotational applications can potentially be replaced by active magnetic bearings (AMBs). AMBs levitate the rotor via contact–free, actively controlled, electromagnetic forces. At the North–West University, AMBs are applied to a flywheel unin–terrupted power supply (Fly–UPS) system. Regrettably, AMBs are inherently open–loop un–stable because of the inverse displacement–force relationship, and for this reason requires closed–loop feedback control. Thus, the feasibility of multivariable H control for a Fly–UPS system is investigated. At present, the Fly–UPS system is being controlled by a number of decentralized single–input single–output (SISO), PD controllers. Ultimately, the combination of a multivariable plant, inherent instability, model uncertainties, cross–coupled stiffness, high rotational speed as well as external disturbances, calls for the development of a multivariable robust H controller. The aim of H control is to compute a controller such that the modelling uncertainties, noise and disturbances are minimized according to predefined performance and robustness re–quirements. A state–space model of both the radial AMBs and the axial AMB of the Fly–UPS system is developed and modelled according to the parameters of the physical rotor system. The sen–sors, power amplifiers and anti–aliasing filters are modelled and cascaded onto the rotor model. Finally, the system response is evaluated whereby the developed multivariable model is verified and validated. In the context of robust H control, it is vital in specifying the uncertainty bound (difference weighting function) between the mathematical model and physical system in order to ascer–tain stability robustness. Thus, the additive uncertainties between the nominal simulation model and the physical model at varied rotational speeds are characterised. Furthermore, the mixed sensitivity H control synthesis strategy is described. Different weighting schemes are explained and the six block problem weighting scheme is used for H controller synthesis. A multivariable controller is synthesised with weighting functions relevant to the AMB Fly–UPS system and the controller is reduced to a 19th order controller for implementation.Thesis (M.Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2011.
13
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.
Full textAbstract:
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.
14
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.
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LI, YUNLU. "Modeling and Performance Investigation of a Rotor with Dissimilar Bearing Support System." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1303841533.
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Van, Sittert Elsebi. "A communication sub-system for an active magnetic bearing and drive electronic system / by Elsebi van Sittert." Thesis, North-West University, 2009. http://hdl.handle.net/10394/4915.
Full textAbstract:
The McTronX research group has conducted extensive research concerning Active Magnetic
Bearings (AMBs). This research involved the establishment of an advanced AMB laboratory to aid
in assisting industries that implement AMBs in their applications. This year the McTronX group’s
focus shifted toward the development of an AMB system to be implemented in the Pebble Bed
Modular Reactor (PBMR). The AMB system was designed to be used in a helium blower
application. This involved the development of both the mechanical and the electronic components.
The main goal of this AMB system was to develop a completely digital integrated controller which
is responsible for the control of the AMB system, from here on referred to as the AMB drive and
electronic system (ADES). The need arose for a totally digital system to increase the reliability and
robustness of the ADES. These requirements are crucial in a nuclear environment. In order to
develop a totally digital system a new issue had to be addressed. This involved the
implementation of digital communication.
This project involved the development of a communication sub‐system for the ADES. The
communication system was divided into two sections, the internal and external communication
system. The various interfaces were identified as well as their specifications formulated. The
optimum solution was then selected for each of the interfaces by using a design process that
involved comprehensive trade‐off studies.
The external communication system and the internal communication system were specified and
the necessary hardware was procured. An in‐house developed protocol was developed and
implemented between the internal functional units of the ADES. The designed protocol adhered to
the specific needs of an AMB application.
The protocol was extensively tested by carrying out verification and validation tests and
evaluation plans. The test and evaluation plans for verification were carried out by making use of
simulations and laboratory experiments. Validation of the in‐house developed protocol was
carried out by analyzing the internal communication system whilst the ADES was controlling the
bearing module. During this phase the communication system was also subjected to error
conditions.
The protocol proved to be completely functional, robust and reliable, meeting the performance
specifications and the requirements. During this project a foundation was laid for digital
communication in AMB systems in the McTronX research group.Thesis (M.Ing. (Electronical Engineering))--North-West University, Potchefstroom Campus, 2010.
17
Wang, Muhao. "H∞ optimal control for linear time invariant and parameter dependent conditions in active magnetic bearing systems." Thesis, University of Bath, 2016. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.699000.
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Le, Roux Ronnie Rikus. "An embedded controller for an active magnetic bearing and drive electronic system / by Rikus le Roux." Thesis, North-West University, 2009. http://hdl.handle.net/10394/3992.
Full textAbstract:
The North-West University is currently conducting research in the area of active magnetic bearings (AMBs). The aim of this research is to establish a foundation for the development of AMB systems to be used in industrial applications. These systems should be reliable, effective and economical. The main research objective for this project is to further develop key technologies in order to realize an economical, reliable high-speed AMB drive system to be used in high-speed machinery. The proposed system is the AMB and drive electronic system (ADES), which is a digital control system for controlling AMBs in an industrial environment. The development of the ADES was a group effort. The focus of this dissertation was on selecting and implementing a suitable controller to be used in the ADES. The specification for the ADES was obtained from an industrial high-speed helium blower system.
Selecting the controller was done by concurrently evaluating the conceptual main controller architectures and proposed system architectures. The system architecture is based on an industrial form factor, called compact peripheral component interconnect (PCI), or cPCI, which is an industrial version of PCI. The architectures were evaluated by performing trade-off studies and by weighing each architecture against a decision matrix, which weighs the architectures according to robustness, efficiency, cost, risk, reliability, flexibility and expandability. The selected system architecture includes a single board computer (SBC) with two PCI mezzanine cards (PMCs); a Virtex®-5 field programmable gate array (FPGA) based PMC module, for scheduling real-time tasks, and a Profibus PMC module, which will be used in future iterations of this project to interface the ADES with a programmable logic controller (PLC).
The specified functions were designed, verified and implemented on the selected controller. The digital control was implemented on the FPGA-embedded PowerPC whereas the communication and filters were implemented on the FPGA. The sensitivity analysis placed the system into zone C, which implies a system normally considered unsatisfactory for long-term continuous operation. The system may operate in this condition for a limited period, until a suitable opportunity arises for remedial action. It was also determined that the system is stable for a step-input added to the reference position. Due to the stability of the control, it was possible to suspend the rotor at its designed rating of 19,000 r/min, but due to the high sensitivity rating, prolonged operation at this speed is not recommended.
The selected architecture is versatile and powerful. The FPGA as a co-processor can be used to alleviate the load on the PowerPC, if additional features are required and not enough clock cycles are left on the PowerPC to implement them. The solution is compact, powerful and robust. These features, together with the industrial-based architecture of the system, make the ADES a suitable controller for controlling AMBs in an industrial system.Thesis (M.Ing. (Electrical and Electronic Engineering))--North-West University, Potchefstroom Campus, 2010
19
Cade, Iain Stuart. "A wavelet based approach to the transient control of rotor/active magnetic bearing systems." Thesis, University of Bath, 2006. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.426295.
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Prins, Robert Jack. "System Identification and Calibration Techniques for Force Measurement in Active Magnetic Bearings." Diss., Virginia Tech, 2005. http://hdl.handle.net/10919/30117.
Full textAbstract:
Many processes involving rotating machinery could benefit from the continuous feedback of force applied to the bearings that support the machinery. Such a system could be used to provide diagnostics for process monitoring in a manufacturing application or to provide information for machine health monitoring. Active Magnetic Bearings (AMBs) have the capability to act concurrently as a shaft force sensor and support bearing. This capability stems from the AMB's control system, which is designed to maintain a specific rotor position, regardless of forces acting on the rotor. Researchers have demonstrated the force sensing ability of AMBs; current state of the art methods typically rely on a direct measurement of magnetic flux density as provided by a Hall probe inserted in the magnetic field. In this work, a system identification approach to force measurement is proposed; the proposed approach is applicable to all active magnetic bearings and does not require Hall probes.
Recent developments in system identification of bearing forces (Kasarda et al., 2000) indicate that a different approach is feasible. In the work of Marshall (Marshall et al., 2001), a variety of perturbations are applied to an AMB while the AMB controller signals are interrogated, no outside instrumentation such as force transducers or Hall probes are required. The work of Kasarda and Marshall is the starting point for the work presented here.
The initial work was expanded to include a general characterization of air gap for any rotor position. Although this characterization relies on static testing to identify system parameters, the identified parameters can then be used in the measurement of dynamic forces. The identification procedure provides a measurement of effective air gap length. Effective gap length is used to infer the effective position of the rotor with respect to the stator. This measurement is made for several specific rotor locations. The relationship between the effective rotor positions provided by the identification and the rotor positions reported by the AMB system sensors establishes a coordinate transformation. The procedure is also applied at different shaft rotation angles. In this way rotor runout can be identified.Ph. D.
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Kolařík, František. "Řídicí systém aktivního magnetického ložiska." Master's thesis, Vysoké učení technické v Brně. Fakulta strojního inženýrství, 2011. http://www.nusl.cz/ntk/nusl-229668.
Full textAbstract:
Thesis deals with active magnetic bearing (AMB) levitation control design. Its prototype was done in FSI collaboration with FEKT VUT Brno. The research is focused on communication tools and mathematical model making as well as general AMB issues. Based on this the control design is done an experimentally verified.
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Wroblewski, Adam C. "Model Identification, Updating, and Validation of an Active Magnetic Bearing High-Speed Machining Spindle for Precision Machining Operation." Cleveland State University / OhioLINK, 2011. http://rave.ohiolink.edu/etdc/view?acc_num=csu1318379242.
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Van, Vuuren Pieter Andries. "Robustness estimation of self-sensing active magnetic bearings via system identification / P.A. van Vuuren." Thesis, North-West University, 2009. http://hdl.handle.net/10394/3993.
Full textAbstract:
Due to their frictionless operation active magnetic bearings (AMBs) are essential components
in high-speed rotating machinery. Active magnetic control of a high speed rotating rotor
requires precise knowledge of its position. Self-sensing endeavours to eliminate the required
position sensors by deducing the rotor’s position from the voltages and currents with which it
is levitated. For self-sensing AMBs to be of practical worth, they have to be robust. Robustness
analysis aims to quantify a control system’s tolerance for uncertainty. In this study the stability
margin of a two degree-of-freedom self-sensing AMB is estimated by means of μ-analysis.
Detailed black-box models are developed for the main subsystems in the AMB by means of
discrete-time system identification. Suitable excitation signals are generated for system identification
in cognisance of frequency induced nonlinear behaviour of the AMB. Novel graphs
that characterize an AMB’s behaviour for input signals of different amplitudes and frequency
content are quite useful in this regard. In order to obtain models for dynamic uncertainty in
the various subsystems (namely the power amplifier, self-sensing module and AMB plant), the
identified models are combined to form a closed-loop model for the self-sensing AMB. The
response of this closed-loop model is compared to the original AMB’s response and models for
the dynamic uncertainty are empirically deduced. Finally, the system’s stability margin for the
modelled uncertainty is estimated by means of μ-analysis. The potentially destabilizing effects
of parametric uncertainty in the controller coefficients as well as dynamic uncertainty in the
AMB plant and self-sensing module are examined. The resultant μ-analyses show that selfsensing
AMBs are much less robust for parametric uncertainty in the controller than AMBs
equipped with sensors. The μ-analyses for dynamic uncertainty confirm that self-sensing
AMBs are rather sensitive for variations in the plant or the self-sensing algorithm. Validation
of the stability margins estimated by μ-analysis reveal that μ-analysis is overoptimistic for
parametric uncertainty on the controller and conservative for dynamic uncertainty. (Validation
is performed by means of Monte Carlo simulations.) The accuracy of μ-analysis is critically
dependent on the accuracy of the uncertainty model and the degree to which the system is
linear or not. If either of these conditions are violated, μ-analysis is essentially worthless.Thesis (Ph.D. (Electronical Engineering))--North-West University, Potchefstroom Campus, 2010
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Blumber, Eric Joseph. "Testing of a Magnetically Levitated Rocket Thrust Measurement System Demonstrator for NASA." Thesis, Virginia Tech, 2002. http://hdl.handle.net/10919/33753.
Full textAbstract:
Existing thrust measurement systems (TMSs) at NASA Stennis Space Center use strain gauges and flux plates to measure forces produced by a test article. Alignment and calibration can take two weeks or more every time a piece of hardware or test article is changed. Cross axis loading is also problematic because it is impossible to perfectly align the flex plates and strain gauges in the thrust direction. In response to these problems, a magnetically levitated thrust measurement system has been proposed and a 300lb capacity demonstrator has been designed and built. In this design, the magnetic bearings work concurrently as support bearings and force measurement devices. The demonstrator consists of a floating frame that is completely levitated within a fixed frame by four support bearings carrying loads in the x- and y-direction and seven thrust bearings carrying loads in the z- or thrust direction. Joe Imlach of Imlach Consulting Engineering designed the demonstrator and magnetic bearing components, while Virginia Tech's role has been the application of the multipoint calibration technique including code development, the implementation of a 128-channel data acquisition system, and the overall test verification of the TMS demonstrator.A turnbuckle assembly and magnetostrictive actuator are used in series with a conventional load cell for static and dynamic testing, respectively. Both current based and flux based force equations were used to measure the reaction forces at the bearings. The static results using the current based equations including the current based fringing equations resulted in accuracies of 93% of full load, while the static results using the flux based equations including the flux based fringing equations resulted in accuracies of 99.5% of full load. These accuracies can be compared to accuracies of 83-90% seen in previous work using magnetic bearings to measure forces by monitoring currents and to accuracies of about 99% in previous work using magnetic bearings to measure forces by monitoring fluxes. All of the improved accuracies were made possible through the implementation of a calibration technique known as the multipoint method and the implementation of a gap dependent fringing correction factor developed by Joe Imlach. The demonstrator was not outfitted with accelerometers so the inertia of the floating frame could not be accounted for, limiting the scope of dynamic testing. However, the tests confirmed the ability of the demonstrator to measure dynamic loads in general.Master of Science
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Wei, Chunsheng [Verfasser], and Dirk [Akademischer Betreuer] Söffker. "Controller Design and Optimization for Rotor System Supported by Active Magnetic Bearings / Chunsheng Wei. Betreuer: Dirk Söffker." Duisburg, 2015. http://d-nb.info/1080478795/34.
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Wei, Chunsheng Verfasser], and Dirk [Akademischer Betreuer] [Söffker. "Controller Design and Optimization for Rotor System Supported by Active Magnetic Bearings / Chunsheng Wei. Betreuer: Dirk Söffker." Duisburg, 2015. http://d-nb.info/1080478795/34.
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Costa, Eduardo Alves da. "Mancal magnético ativo aplicado a um motor de indução linear tubular." Universidade de São Paulo, 2009. http://www.teses.usp.br/teses/disponiveis/3/3139/tde-21122009-131641/.
Full textAbstract:
O Motor Assíncrono Tubular para Aplicação na Extração de Óleo do Subsolo MATÆOS foi desenvolvido na Escola Politécnica da Universidade de São Paulo (EPUSP) com a função de acionar diretamente uma bomba de sucção, instalada no fundo de um poço de petróleo em terra. Dando continuidade aos trabalhos realizados na EPUSP envolvendo sistemas de levitação magnética, foi desenvolvido um mancal magnético ativo (AMB - Active Magnetic Bearing), aplicado ao protótipo do motor em substituição ao mancal mecânico tradicional existente. O projeto abrange a construção de um protótipo de mancal magnético composto das partes mecânicas, elétricas e de software necessárias ao funcionamento do sistema. O projeto do eletroímã foi realizado por meio do método dos elementos finitos (MEF), para análise da densidade de fluxo e da relação entre a força radial e a corrente elétrica nas bobinas. O controle da levitação do mancal é realizado por meio de controlador digital com placas conversoras AD/DA e algoritmo de controle implementado em hardware FPGA. Utilizando o modelo do sistema, os controladores são sintonizados para atender aos requisitos de estabilidade e rejeição de perturbações, que desviem o entreferro do seu valor nominal. Na configuração do AMB, ao invés do sistema tradicional com oito pólos, um conceito diferente é adotado. Neste, uma máquina primitiva bearingless é excitada com corrente contínua e usada como mancal magnético. Os resultados experimentais obtidos com o protótipo em funcionamento mostram que o sistema em malha fechada é estável e apresenta uma resposta transitória satisfatória.A tubular linear induction motor applied to onshore oil exploitation, named MATÆOS (which is in the Portuguese acronym for Tubular Asynchronous Motor for Onshore Oil Exploitation) was built at Escola Politécnica da Universidade de São Paulo (EPUSP). Its purpose is to directly drive the sucker-rod pump installed in the down hole of the oil well. In continuing the research accomplished at EPUSP concerning magnetic levitation systems, an Active Magnetic Bearing (AMB) was developed and applied to the prototype of the motor in substitution to the existing traditional bearing. The design includes the construction of the magnetic bearing prototype composed of mechanical, electric and software components required to the operation of the system. The electromagnet design was accomplished using the Finite Element Method (FEM) in the analysis of both the flux density and the relationship between the radial force and the suspension winding current. The magnetic bearing levitation control is executed by a digital controller using an AD/DA converter and a control algorithm implemented in FPGA hardware. Using the system model, the controllers are tuned to provide both stability and rejection of disturbances that tend to move the air gap from its nominal value. Instead of the usual eight-pole AMB, a different concept is adopted where a DC-excited primitive bearingless machine is used as a magnetic bearing. The experimental results obtained with the prototype in operation show that the closed-loop system is stable and exhibits a satisfactory transient response.
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Aucamp, Christiaan Daniël. "Model predictive control of a magnetically suspended flywheel energy storage system / Christiaan Daniël Aucamp." Thesis, North-West University, 2012. http://hdl.handle.net/10394/8601.
Full textAbstract:
The goal of this dissertation is to evaluate the effectiveness of model predictive control (MPC)
for a magnetically suspended flywheel energy storage uninterruptible power supply (FlyUPS).
The reason this research topic was selected was to determine if an advanced control technique
such as MPC could perform better than a classical control approach such as decentralised
Proportional-plus-Differential (PD) control.
Based on a literature study of the FlyUPS system and the MPC strategies available, two MPC
strategies were used to design two possible MPC controllers were designed for the FlyUPS,
namely a classical MPC algorithm that incorporates optimisation techniques and the MPC
algorithm used in the MATLAB® MPC toolbox™. In order to take the restrictions of the system
into consideration, the model used to derive the controllers was reduced to an order of ten
according to the Hankel singular value decomposition of the model.
Simulation results indicated that the first controller based on a classical MPC algorithm and
optimisation techniques was not verified as a viable control strategy to be implemented on the
physical FlyUPS system due to difficulties obtaining the desired response. The second
controller derived using the MATLAB® MPC toolbox™ was verified to be a viable control
strategy for the FlyUPS by delivering good performance in simulation.
The verified MPC controller was then implemented on the FlyUPS. This implementation was
then analysed in order to validate that the controller operates as expected through a
comparison of the simulation and implementation results. Further analysis was then done by
comparing the performance of MPC with decentralised PD control in order to determine the
advantages and limitations of using MPC on the FlyUPS.
The advantages indicated by the evaluation include the simplicity of the design of the controller
that follows directly from the specifications of the system and the dynamics of the system, and
the good performance of the controller within the parameters of the controller design. The
limitations identified during this evaluation include the high computational load that requires a
relatively long execution time, and the inability of the MPC controller to adapt to unmodelled
system dynamics.
Based on this evaluation MPC can be seen as a viable control strategy for the FlyUPS, however
more research is needed to optimise the MPC approach to yield significant advantages over
other control techniques such as decentralised PD control.Thesis (MIng (Computer and Electronic Engineering))--North-West University, Potchefstroom Campus, 2013
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Tombul, Galip Serdar. "On the application of nonlinear systems theory to active magnetic bearings." Thesis, University of Sheffield, 2011. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.578704.
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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.
Full textAbstract:
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.
Full textAbstract:
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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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.
Full textAbstract:
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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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.
Full textAbstract:
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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Bean, Jaco. "Vibration characterization of an active magnetic bearing supported rotor / J. Bean." Thesis, North-West University, 2011. http://hdl.handle.net/10394/7029.
Full textAbstract:
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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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.
Full textAbstract:
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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Marais, Charl Henri. "High speed flexible rotor active magnetic bearing control / by Charl Henri Marais." Thesis, North-West University, 2006. http://hdl.handle.net/10394/1084.
Full textAbstract:
The School of Electrical, Electronic and Computer Engineering at the North-West University is in the
process of establishing a knowledge base on Active Magnetic Bearings (AMBs). In support of this
initiative this project is aimed at characterising an in-house developed double radial heteropolar AMB
system.
Before characterising the AMB system the acoustic noise problem of the system had to be addressed and
reduced to an acceptable level. To reduce the acoustic noise of the system a noise analysis was done to
determine the source of the noise. The analysis revealed radiated noise from the electromagnets and
power amplifiers (PA) and conducted noise on the signals to and from the controller. The conducted noise
is reduced by using anti-aliasing (AAF) and anti-imaging filters (AIF) before and after the controller. The
effect of the radiated noise is reduced by synchronising the sampling of the sensor signals with the
switching of the PAS.
The characterisation of the AMB system starts with a Mass-Spring-Damper (MSD) simulation which is
a linear representation of the AMB system. This simulation is used to understand the basic principles of a
second order system and to compare its response to the nonlinear AMB simulation. The following step in
characterising the AMB system is to determine the effect of filters on the nonlinear AMB simulation and
to determine the simulation characteristics. These characteristics are compared to the MSD simulation
and the actual AMB system. The characteristics compared between the MSD and AMB simulations are
the static, second order and dynamic stiffness.
The actual AMB system was characterised before and after the AAF and AIF were implemented. This
provided the opportunity to determine the effects of the filters on the actual system and not just from
simulations. The characteristics measured on the actual AMB system include the static stiffness, dynamic
stiffness, rotor dynamics and system sensitivity. The stiffness characteristics of the actual AMB system
showed good correlation with the linear and nonlinear simulations. The measured results showed a
decrease in static stiffness and an increase in system sensitivity because of the AAF, AIF and controller
pole. It also showed that the effects of the filters can be reduced by moving the controller pole to a higher
frequency.
The characterisation of the double radial heteropolar AMB system provides a fundamental understanding
of the AMB performance aiding the AMB design process.Thesis (M. Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2006.
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Pretorius, Morné. "Comprehensive active magnetic bearing modelling taking rotor dynamics into account / M. Pretorius." Thesis, North-West University, 2008. http://hdl.handle.net/10394/2647.
Full textAbstract:
The McTronX Research Group at the North-West University is conducting research in the field of Active Magnetic Bearings (AMBs) with the aim of establishing a knowledge base for future industry consultation. AMBs are environmentally friendly and are a necessity in the pebble bed modular reactor (PBMR), a South-African initiated project, which is predicted to be the means of supplying Africa and many other countries with modular energy in the future. Aside from the PBMR, there are numerous other AMB industrial applications.
The aim of this project is to develop a comprehensive AMB model that considers the effect that rotor dynamics has on an AMB system. This model is used to analyse a double radial AMB, capable of suspending a rigid- and flexible rotor, to explain previously noticed phenomena. Two modelling methods are focussed on namely the System Matrix Method and Transfer Matrix Method (TMM) both of which are implemented in MATLAB®.
The rigid rotor model is firstly implemented as a point mass in state-space form followed by use of the TMM to analyse its bending modes. The stability and critical speeds of the system are analysed due to a change in the supports' properties along with rotor gyroscopy and its effect on the system.
During analysis of the flexible rotor the TMM was used via a similar approach as was followed with the rigid rotor.
The results indicate that the system is experiencing lower than expected damping due to the model that is used within the control loop. The previously assumed rotor model in the control loop is not sufficient to describe its complex behaviour. This causes the unexpected damping characteristics.
This project suggests future work to be conducted in expanding the frequency domain model of the rotor within the control loop to account for its physical shape.Thesis (M.Ing. (Computer and Electronical Engineering))--North-West University, Potchefstroom Campus, 2009.
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Raju, K. V. S. "Finite element based non-linear transient analysis of active magnetic bearing turbomachinery." Thesis, Virginia Tech, 1996. http://hdl.handle.net/10919/45082.
Full textAbstract:
The active magnetic bearing (AMB) is a relatively new technology in which the suspension forces are generated magnetically without any contact. Although there are many advantages of AMB technology over conventional bearing design, its major selling point is the claim of reduced maintenance and longer run times between mandatory shutdowns to replace worn or defective components. This claim is, however, somewhat diluted by the fact that the majority of industrial applications have relied upon anti-friction backup bearings. These backup bearings are, in the event of control system failure or limited operation during momentary overload conditions, essential for the protection of AMB rotor, stator and other stationery seals along the shaft. The increase in the number of critical path machinery using AMB technology has focused awareness and necessity for proper design of these auxiliary bearings to avoid additional unwanted down-time.
In this research, the equations of equilibrium governing the dynamic response of a rotor-bearing system were formulated and then solved using an appropriate numerical algorithm capable of analyzing this non-linear system. An efficient transient response analysis program was developed for evaluation of shock loading, blade loss and rotor drop of active magnetic bearing machinery. This program can analytically predict the path of the rotor and the instantaneous loads acting on the backup bearings during rotor drop which would help in the design of more reliable backup bearings without evaluating them experimentally. Parameter variation study was conducted analytically to observe the influence of some important factors on the dynamics of rotor drop phenomenon. The results from this program have also been compared to the experimental data obtained from the Virginia Tech Rotor Dynamics Laboratory AMB Rotor Drop Test Rig.Master of Science
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Ishii, Toshiyasu. "Transient response technique applied to active magnetic bearing machinery during rotor drop." Thesis, Virginia Tech, 1990. http://hdl.handle.net/10919/41937.
Full textAbstract:
The active magnetic bearing (AMB) is a relatively new technology which has
many advantages compared with conventional bearing design. In an AMB system,
the rolling-element back-up bearings are indispensable to protect the magnetic
bearing rotor and stator, and other stationary seals along the rotor shaft. In this
paper, a theoretical formulation is proposed and solved numerically to examine the
transient response of the flexible rotor, from the time just previous to the AMB
shuts down and including the rotor drop onto the back-up bearing. The backward
whirl of the rotor, which may lead to the destructive damage of the machinery, has
been analytically predicted at very light support damping and very high support
damping. Also, the vibration due to the non-linearity of the contact point geometry
has been included in the analysis. The influence of the support damping on the
displacement of the disk and also the contact force between the journal and the
inner-race of the back-up bearing have been computed for various rotor system
parameters. By comparing these results with the optimum support damping for
the simple flexible rotor model, it is shown that this support damping optimization
can be applicable for specifying the required optimum range of support damping
for the back-up bearings of AMB systems.
Master of Science
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Lozano, Jauregui John Hugo. "Control for an active magnetic bearing machine with two hybrid electromagnet actuators." Master's thesis, Pontificia Universidad Católica del Perú, 2021. http://hdl.handle.net/20.500.12404/19548.
Full textAbstract:
This thesis work begins with the revision of state of the art about active magnetic bearings
(AMB), the mathematical methods used to obtain geometric and physical parameters that
will influence in the mechanical, electrical design and control system proposed by this
prototype.
The control system will activate the magnetic bearing to center its shaft, for which it is joined
a variable load in order to study the best control performance under different load over the
rotor proposed by requirements. When the rotor is not controlled in its own axis even though
variable load, a position error will occur that will be corrected by the program of a control
system that will center the shaft (rotor).
For this design was evaluated generalized AMB models [2], [3], [4] to validate the best
identification for this design, furthermore as a consequence to get the best performance for
the control system as it was achieved by generalized models and it was evaluated the
advantage of this AMB machine through “Two hybrid electromagnet actuators” and variable
load fixed to its shaft. For this reason, it was necessary to test a simple AMB with only one
electromagnet actuator [4], due to compare enhancement of hybrid characteristics for the
electromagnet actuators, for which, also it was evaluated how many actuators could be
necessary to join to an AMB system with the target to get the control. It means, in this work
there are comparisons between a simple AMB, generalized AMB models and this design,
owing to show the achievements of this design.
In order to show experimental results in state of the art, it is known that Siemens presented
Simotics Active Magnetic Bearings technology for wear free operation in large – machine
applications, regulated magnetic fields hold the rotor in suspension precisely without oil or
contact, to make this task, sensors capture the position of the shaft 16000 times per second
and a regulator adjusts the magnetic field to keep the rotor hovering precisely in the bearing
center [1].
By other side the author [4] describes the experimental results in which is proposed that at
low speed the bearing parameters are mainly determined by the controller characteristics.
While at high speed, the bearing parameters are not only related to the control rule but also
related to the speed. This may be due to the influence of eddying effect. [4]
Furthermore, by author [3], the algorithm to get fast responses in front of disturbances, the
disadvantages of these algorithms are given by not enough memory space to execute them,
due to computing time is short compared with rotor displacement response time, and it is
defined that it could be possible to execute the control algorithm through a real-time
operating system to obtain the desired response [3].
Finally, in reference [6] it is described about filtering every noise as additive white
Gaussian noise, by a predictive filter, which is obtained by analyzing Least Mean Square
(LMS) and feedback/feedforward algorithm.
41
Ehtemam, Haghighi Vahid. "Modelling, Simulation and Experimental Diagnostics of Failures in Rotor Systems Supported by Active Magnetic Bearings." Thesis, Curtin University, 2019. http://hdl.handle.net/20.500.11937/75982.
Full textAbstract:
In this thesis, a comprehensive approach for troubleshooting and diagnostics of rotors supported with Active Magnetic Bearings is demonstrated. For this purpose, a SKF MBRotor-II Test Stand supported by an industrial controller and its software package, is modelled and simulated to provide full understanding of the test rig. Finally, various mechanical and controller faults were investigated by using simulation and measured data.
42
Lundh, Joachim. "Model Predictive Control for Active Magnetic Bearings." Thesis, Linköpings universitet, Reglerteknik, 2012. http://urn.kb.se/resolve?urn=urn:nbn:se:liu:diva-81325.
Full textAbstract:
This thesis discuss the possibility to position control a rotor levitated with active magnetic bearings. The controller type considered is model predictive control which is an online strategy that solves an optimization problem in every sample, making the model predictive controller computation-intense. Since the sampling time must be short to capture the dynamics of the rotor, very little time is left for the controller to perform the optimization. Different quadratic programming strategies are investigated to see if the problem can be solved in realtime. Additionally, the impact of the choices of prediction horizon, control horizon and terminal cost is discussed. Simulations showing the characteristics of these choises are made and the result is shown.Det här examensarbetet diskuterar möjligheten att positionsreglera en rotor som leviteras på aktiva magnetlager. Reglerstrategin som används är modellbaserad prediktionsreglering vilket är en online-metod där ett optimeringsproblem löses i varje sampel. Detta gör att regulatorn blir mycket beräkningskrävande. Samplingstiden för systemet är mycket kort för att fånga dynamiken hos rotorn. Det betyder att regulatorn inte ges mycket tid att lösa optimeringsproblemet. Olika metoder för att lösa QP-problem betraktas för att se om det är möjligt att köra regulatorn i realtid. Dessutom diskuteras hur valet av prediktionshorisont, reglerhorisont och straff på sluttillståndet påverkar regleringen. Simuleringar som visar karakteristiken av dessa val har utförts.
43
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.
44
Li, Yuan-Chen, and 李元辰. "Radial Active Magnetic Bearing System Design and Control." Thesis, 2014. http://ndltd.ncl.edu.tw/handle/12741084332167693045.
Full textAbstract:
碩士大葉大學
電機工程學系
102
Due to the manufacturing process of products depend on high accuracy, requirement of high precision machining technology is becoming more and more important. For this reason, manufactory reduce rust in manufacturing process environment as much as possible. Therefore non-contact technology and some related technology have attracted more and more attention. Magnetic levitation (Maglev) technology is the stable equilibrium of an object without contact and can be achieved using electric or magnetic forces. In this paper, we analyze the benefit of magnetic suspended system by magnetic levitation ball system. The radial active magnetic bearing (AMB) system was developed based on analysis of magnetic levitation ball system. This paper consists system test rig, electric circuit of position sensor, transfer equation of position sensor and electric circuit of power amplifier. Controller with PID control rule was applied to maglev ball and radial AMB system. We determined PID control parameters by Routh-Hurwitz stability criterion and wrote program with C++ language for these systems. In this research, we solved control issue of magnetic levitation ball and built the radial AMB system. Finally, we used the maglev ball system and the radial AMB system test rig performing simulations and showing the experiment results.
45
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.
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Noshadi, Amin. "System Identification and High Performance Controllers of Active Magnetic Bearing Systems." Thesis, 2015. https://vuir.vu.edu.au/31831/.
Full textAbstract:
In recent years, active magnetic bearing systems (AMBs) have attracted the
attention of researchers as suitable replacements for conventional mechanical and
hydrostatic bearings. The absence of mechanical frictions, high-precision and low
maintenance costs have all made AMBs suitable technologies for high-speed and
high-precision applications. However, along with the numerous advantages, several
challenges have hindered the widespread applications of these systems. AMBs
are inherently open-loop unstable and hence feedback controllers are essential for
stabilisation of AMB equipped systems. The multiple-input multiple-output nature
of AMBs and the presence of high-frequency resonant modes further exacerbate
the problem of modelling and control design of such systems.
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Yung-Hsiang, Kung, and 龔詠翔. "Dynamic Analysis and Identification of Octopole Active Magnetic Bearing System." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/48646520818500088762.
Full textAbstract:
碩士國立中正大學
機械系
93
With the development of technology, high rotational speed machines become the mainstream to mechanical design recently. The magnetic bearing is regarded as an ideal bearing which has many superior characteristics than the conventional bearing. The characteristics include non-contact, non-lubrication, widely range of working temperature and long life working etc.. In this study, the analysis of system characteristics and parameter identification are focused on the octoploe electromagnetic bearing system. In the analysis of system characteristics, finite element method (FEM) and Lagrange approach are employed to derive the system equations of motion. And the decentralized PD controller is adopted to control the rotor system and system stability is also analyzed. The numerical integration method is used to investigate the system characteristics. The hybrid identification method is combination of the method proposed by Yasuda et al. and Gauss-Newton algorithm, and it uses the simulation data which is employed by Runge-Kutta method. After discussing analysis of the electromagnetic force model, a simple model of the non-linear magnetic force is proposed by this study and its identified results have a good accidence with the real system. By simplifying the items of Fourier series expansion and collocating with convergence of Gauss-Newton algorithm, accurate parameters can be solved faster and the error is lower than 5%. However, Kp and Kd of the decentralized PD controller influence the identified results and the system characteristics. According to the numerical results of this study, identified results of the hybrid method are better than Yasuda’s method in the bad state of the controller.
48
Huang, Cheng-Han, and 黃承翰. "Experimental Verification of a 3-Pole Active Magnetic Bearing System." Thesis, 2001. http://ndltd.ncl.edu.tw/handle/40136711008312100004.
Full textAbstract:
碩士國立中正大學
機械系
89
This study is experiment verification of 3-pole active magnetic bearing system. A magnetically coupled nonlinear model is considered here, and we select a linear state-feedback controller to control system. From numerical simulation, the system can achieves stabilization by using state-feedback controller. Moreover, we set up a procedure of design about 3-pole active magnetic bearing, and finish the experiment of 3-pole active magnetic bearing system.
49
Liao, Yi-Peng, and 廖宜鵬. "Development of a Contact-Free System with Active Magnetic Bearing." Thesis, 1997. http://ndltd.ncl.edu.tw/handle/67118916444701261851.
Full textAbstract:
碩士國立中央大學
機械工程學系
85
This thesis, two aspects of active magnetic bearings (AMB) arediscussed. The first one is the development of a contact-free motor withAMB. The rotor of motor is constrained within its hovering position bythree active magnetic bearings replaced of the conventional ballbearings, since the AMB allows higher speed rotation and lowerfrictional loss than conventional bearings. Here, we discuss how todesign a suitable AMB for the specified system. The second aspect is the design of controller for AMB system. Threecontrol algorithm are applied. The first is PID controller, and itsadvantages are easily implemented and simple calculated. The secondmethod is Self-Tuning PID controller. This adjust the gains of PIDcontroller by different response of system based on Fuzzy controllingrule. It can increase the robustness and stability of PID controller butskip the processes of fuzzification and defuzzification. The last one,the sliding mode control i s discussed. It can prevent efficiently theunknown effect from system''s uncertainties and disturbances, like theexternal magnetic forces from the motor''s electromagnet.
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Li, Guoxin. "Robust stabilization of rotor-active magnetic bearing systems/." 2007. http://wwwlib.umi.com/dissertations/fullcit/3248091.
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