Dissertations / Theses on the topic 'Modelling; induction machines; modelling'
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Göl, Özdemir. "Dynamic modelling of induction machines /." Title page, contents and abstract only, 1993. http://web4.library.adelaide.edu.au/theses/09PH/09phg595.pdf.
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Abdi-Jalebi, Ehsan. "Modelling and instrumentation of Brushless Doubly-Fed (induction) Machines." Thesis, University of Cambridge, 2007. https://www.repository.cam.ac.uk/handle/1810/252033.
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Ahmed, M. M. "Modelling of inverter-fed induction machine." Thesis, University of Manchester, 1985. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.234246.
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Potter, Benjamin Alexander. "Investigation into the input impedance of induction machines using measurement and modelling." Thesis, University of Reading, 2007. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.501347.
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This thesis presents material that aims to further the understanding of the variation of the input impedance of induction machines with frequency. The input impedance is shown to be of importance when predicting or mitigating the effects of harmonics in machines that are driven by an inverter. The main body of this thesis consists of experimental results from a study that characterises the input impedance of thirteen different induction machines of various sizes and with different numbers of poles.
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Andersen, Peter Scavenius. "Modelling and analysis of asynchronous and synchronous torques in split-phase induction machines." Thesis, University of Glasgow, 2008. http://theses.gla.ac.uk/82/.
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In this thesis, the nature of asynchronous and synchronous torques in a split-phase induction machine is investigated and quantified. The equivalent circuit for this type of machine is derived using the rotating field theory. It is extended to include harmonic effects. Using this model, winding harmonics and permeance harmonics may be calculated independently of each other so that the model can be used to analyse asynchronous torques from winding harmonics as well as synchronous torques from permeance harmonics. These are calculated separately. The asynchronous torques appear as perturbations in the steady-state torque-speed curve while the synchronous torques only appear at specific speeds. The synchronous torques are superimposed onto the torque-speed curves to model both effects together. The model predictions are compared against test results using purpose-built experimental machines together with production machines. These have varying rotor bar number and skew. Different methods are used to assess the synchronous torques. It is found that measuring synchronous locking torque is not a straightforward matter; however, reasonable agreement is found between calculation and measurement. The work highlights the need for the correct choice of stator and rotor slot numbers together with the effect skew has on reducing the synchronous and asynchronous locking torques.
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Okoro, Ogbonnaya Inya. "Dynamic and thermal modelling of induction machine with non-linear effects." Kassel : Kassel Univ. Press, 2002. http://deposit.d-nb.de/cgi-bin/dokserv?idn=969576749.
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Sprooten, Jonathan. "Finite element and electrical circuit modelling of faulty induction machines: Study of internal effects and fault detection techniques." Doctoral thesis, Universite Libre de Bruxelles, 2007. http://hdl.handle.net/2013/ULB-DIPOT:oai:dipot.ulb.ac.be:2013/210674.
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This work is dedicated to faulty induction motors. These motors are often used in industrial applications thanks to their usability and their robustness. However, nowadays optimisation of production becomes so critical that the conceptual reliability of the motor is not sufficient anymore. Motor condition monitoring is expanding to serve maintenance planning and uptime maximisation. Moreover, the use of drive control sensors (namely stator current and voltage) can avoid the installation and maintenance of dedicated sensors for condition monitoring.Many authors are working in this field but few approach the diagnosis from a detailed and clear physical understanding of the localised phenomena linked to the faults. Broken bars are known to modulate stator currents but it is shown in this work that it also changes machine saturation level in the neighbourhood of the bar. Furthermore, depending on the voltage level, this change in local saturation affects the amplitude and the phase of the modulation. This is of major importance as most diagnosis techniques use this feature to detect and quantify broken bars. For stator short-circuits, a high current is flowing in the short-circuited coil due to mutual coupling with the other windings and current spikes are flowing in the rotor bars as they pass in front of the short-circuited conductors. In the case of rotor eccentricities, the number of pole-pairs and the connection of these pole-pairs greatly affect the airgap flux density distribution as well as the repartition of the line currents in the different pole-pairs.
These conclusions are obtained through the use of time-stepping finite element models of the faulty motors. Moreover, circuit models of faulty machines are built based on the conclusions of previously explained fault analysis and on classical Park models. A common mathematical description is used which allows objective comparison of the models for representation of the machine behaviour and computing time.
The identifiability of the parameters of the models as well as methods for their identification are studied. Focus is set on the representation of the machine behaviour using these parameters more than the precise identification of the parameters. It is shown that some classical parameters can not be uniquely identified using only stator measurements.
Fault detection and identification using computationally cheap models are compared to advanced detection through motor stator current spectral analysis. This last approach allows faster detection and identification of the fault but leads to incorrect conclusions in low load conditions, in transient situations or in perturbed environments (i.e. fluctuating load torque and unideal supply). Efficient quantification of the fault can be obtained using detection techniques based on the comparison of the process to a model.
Finally, the work provides guidelines for motor supervision strategies depending on the context of motor utilisation.
Doctorat en Sciences de l'ingénieur
info:eu-repo/semantics/nonPublished
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Okoro, Ogbonnaya Inya [Verfasser]. "Dynamic and thermal modelling of induction machine with non-linear effects / Ogbonnaya Inya Okoro." Kassel : Kassel Univ. Press, 2002. http://d-nb.info/969576749/34.
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Cordier, Julien [Verfasser], Ralph [Akademischer Betreuer] Kennel, Ralph [Gutachter] Kennel, and Jean-Luc [Gutachter] Thomas. "Modelling space harmonics in induction machines for real-time applications / Julien Cordier ; Gutachter: Ralph Kennel, Jean-Luc Thomas ; Betreuer: Ralph Kennel." München : Universitätsbibliothek der TU München, 2020. http://d-nb.info/1203799578/34.
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Jorks, Hai Van [Verfasser], Thomas [Akademischer Betreuer] Weiland, Kay [Akademischer Betreuer] Hameyer, Andreas [Akademischer Betreuer] Binder, Gerd [Akademischer Betreuer] Griepentrog, and Sebastian [Akademischer Betreuer] Schöps. "Transmission Line Modelling for Inverter-Fed Induction Machines / Hai Van Jorks. Betreuer: Thomas Weiland ; Kay Hameyer ; Andreas Binder ; Gerd Griepentrog ; Sebastian Schöps." Darmstadt : Universitäts- und Landesbibliothek Darmstadt, 2015. http://d-nb.info/1110981155/34.
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Malik, Naveed ur Rehman. "Modelling, Analysis, and Control Aspects of a Rotating Power Electronic Brushless Doubly-Fed Induction Generator." Doctoral thesis, KTH, Elektrisk energiomvandling, 2015. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-174349.
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This thesis deals with the modeling, analysis and control of a novel brushlessgenerator for wind power application. The generator is named as rotatingpower electronic brushless doubly-fed induction machine/generator (RPEBDFIM/G). A great advantage of the RPE-BDFIG is that the slip power recoveryis realized in a brushless manner. This is achieved by introducing an additionalmachine termed as exciter together with the rotating power electronicconverters, which are mounted on the shaft of a DFIG. It is shown that theexciter recovers the slip power in a mechanical manner, and delivers it backto the grid. As a result, slip rings and carbon brushes can be eliminated,increasing the robustness of the system, and reducing the maintenance costsand down-time of the turbine. To begin with, the dynamic model of the RPE-BDFIG is developed andanalyzed. Using the dynamic model, the working principle of the generatoris understood and its operation explained. The analysis is carried out atspeeds, ±20% around the synchronous speed of the generator. Moreover, thedynamics of the generator due to external load-torque disturbances are investigated.Additionally, the steady-state model is also derived and analyzed forthe machine, when operating in motor mode. As a next step, the closed-loop control of the generator is considered indetail. The power and speed control of the two machines of the generator andthe dc-link voltage control is designed using internal model control (IMC)principles. It is found that it is possible to maintain the stability of thegenerator against load-torque disturbances from the turbine and the exciter,at the same time maintain a constant dc-link voltage of the rotor converter.The closed-loop control is also implemented and the operation of the generatorwith the control theory is confirmed through experiments.In the third part of the thesis, the impact of grid faults on the behaviourof the generator is investigated. The operation of the generator and its responseis studied during symmetrical and unsymmetrical faults. An approachto successful ride through of the symmetrical faults is presented, using passiveresistive network (PRN). Moreover, in order to limit the electrical and mechanicaloscillations in the generator during unsymmetrical faults, the dualvector control (DVC) is implemented. It is found that DVC to a certain extentcan be used to safeguard the converter against large oscillations in rotorcurrents. Finally, for completeness of the thesis, a preliminary physical design ofthe rotating power electronic converter has been done in a finite elementsoftware called ANSYS. The thermal footprint and the cooling capability,with estimates of the heatsink and fan sizes, are presented. Besides, another variant of a rotating electronic induction machine whichis based on the Lindmark concept and operating in a single-fed mode is also investigated. It’s steady-state model is developed and verified through experiments.QC 20151006
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Boulanger, Isabelle. "Lillgrund Wind Farm Modelling and Reactive Power Control." Thesis, KTH, Elektriska energisystem, 2009. http://urn.kb.se/resolve?urn=urn:nbn:se:kth:diva-119256.
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The installation of wind power plant has significantly increased since several years due to the recent necessity of creating renewable and clean energy sources. Before the accomplishment of a wind power project many pre-studies are required in order to verify the possibility of integrating a wind power plant in the electrical network. The creation of models in different software and their simulation can bring the insurance of a secure operation that meets the numerous requirements imposed by the electrical system. Hence, this Master thesis work consists in the creation of a wind turbine model. This model represents the turbines installed at Lillgrund wind farm, the biggest wind power plant in Sweden. The objectives of this project are to first develop an accurate model of the wind turbines installed at Lillgrund wind farm and further to use it in different kinds of simulations. Those simulations test the wind turbine operating according to different control modes. Also, a power quality analysis is carried out studying in particular two power quality phenomena, namely, the response to voltage sags and the harmonic distortion. The model is created in the software PSCAD that enables the dynamic and static simulations of electromagnetic and electromechanical systems. The model of the wind turbine contains the electrical machine, the power electronics (converters), and the controls of the wind turbine. Especially, three different control modes, e.g., voltage control, reactive power control and power factor control, are implemented, tested and compared. The model is tested according to different cases of voltage sag and the study verifies the fault-ride through capability of the turbine. Moreover, a harmonics analysis is done. Eventually the work concludes about two power quality parameters.
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Hikkaduwa, Liyanage Diana Aroshanie. "Modelling and control of a novel single phase generator based on a three phase cage rotor induction machine." Thesis, Curtin University, 2015. http://hdl.handle.net/20.500.11937/250.
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This thesis develops the mathematical modelling and the closed loop control of a single-phase induction generator based on a three-phase cage rotor machine suitable for renewable energy conversion. Comprehensive dynamic and steady state models are developed in stationary ‘αβ’ reference frame and the accuracy is verified by comparing the theoretical results with the laboratory experimental results. Closed loop feedback regulator is designed to regulate the output voltage and frequency at the rated conditions.
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Chrin, Phok. "Contribution to electric energy generation for isolated-rural areas using 2nd life components and renewable energies : modelling and control of an induction generator." Thesis, Toulouse 3, 2016. http://www.theses.fr/2016TOU30137.
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Le Cambodge est un pays situé en Asie du Sud-Est, avec grand potentiel de ressources en énergies renouvelables. Même fort de ce potentiel, la puissance électrique actuellement installée n'est pas suffisante pour tout le pays. Environ 80% de la population vit dans les zones rurales et 75% des ménages sont sans réseau électrique. Ils utilisent une batterie, le moteur diesel, des bougies ou du kérosène pour l'éclairage, la télévision, les multimédia et autres appareils ménagers. Une minorité des citoyens, dans la partie nord utilise des modules pico hydro électriques acheté dans les pays voisins pour éclairage. Mais la tension de sortie et la fréquence ne sont pas vraiment stables en cas de modification de la charge ou de la vitesse de rotation de la turbine. La durée de vie des appareils électroménagers peut ainsi être réduite et des réparations locales sont nécessaires. Des millions de Cambodgiens ne peuvent pas accéder à l'énergie électrique en raison de deux facteurs principaux : les barrières technologiques et les coûts d'investissement élevés. Nos activités de recherche visent à éliminer ces barrières technologiques en concevant des systèmes de production d'énergie pico-hydroélectrique avec une installation rapide et peu coûteuse, simple et adaptée à une application locale tout en gardant une qualité de l'alimentation électrique satisfaisante. La première partie de cet ouvrage décrit la situation de l'énergie dans les zones rurales du Cambodge où les gens sont confrontés à un manque d'alimentation électrique. En conséquence, ils ne peuvent ni améliorer leur niveau de vie, ni développer leur communauté. Les villageois riches utilisent une batterie de voiture, des systèmes photovoltaïques ou pico-hydroélectriques alors que les villageois pauvres utilisent des bougies ou du kérosène pour l'éclairage. Des entreprises locales fournissent des solutions électriques basées sur des énergies renouvelables, mais les prix sont inabordables et loin de leurs attentes. Par conséquent, une solution originale est proposée dans cette thèse avec la récupération de composants électriques d'occasion en vue de la mise en œuvre d'un nouveau système de génération d'électricité pour les zones rurales isolées. Il s'agit ici d'innovation frugale pour le bas de la pyramide sociale. Les composants utilisés sont : machine asynchrone, alimentation sans interruption (UPS), alimentation de PC et d'autres équipements électroniques, etc. Ces composants recyclés peuvent être rassemblés pour former ainsi une solution technologique intéressante permettant de délivrer la puissance de sortie nécessaire. La deuxième partie de ce mémoire présente la modélisation de l'étage de puissance de la machine asynchrone triphasée utilisée comme un générateur asynchrone monophasé avec une phase d'excitation et les deux autres phases connectées en série pour alimenter la charge. Cette configuration est nommée 'Excited Induction Generator (EIG)'Cambodia is a country located in Southeast Asia, with its high potential of renewable energy resource. Even if this country has a high potential for renewable, the installed power is still not high enough to cover the whole country. About 80% of population living in rural areas and 75% of the households live without electricity. They survive by using battery, diesel engine, candle, kerosene for lighting, TV, multimedia and some other household appliances. A few of residents in northern part of the country use pico-hydro power units bought from neighbor countries in order to electrify their houses. In these systems, the output voltage and frequency are not really stable while the load under load or speed variations. Consequently, the lifetime of household appliances could be reduced or the items damaged and local repairs are needed. Moreover, millions of Cambodian people cannot access neither take an advantage from the available energy resources due to two main factors: technology barriers and high investment cost. This research aims to remove technology barriers by designing simple systems for pico-hydro power generation with fast and simple installation, suitable for local applications with high quality of electrical supply. The first part of this work briefly describes the energy situation in rural areas of Cambodia where people are facing the lack of electrical supply which. They cannot neither improve their living standard nor develop their community. Rich villagers use car battery, solar PV applications, pico-hydro power while poor villagers use candle/kerosene for lighting. Local enterprises can provide renewable energy solutions but the prices are unaffordable and far from their expectations. Therefore, an original solution is proposed in this thesis by using wasted electric and electronic equipment (second-life components) to form the new power generation systems for remote rural areas. This is frugal innovation to serve the bottom of the social pyramid. The used components are: induction machine, Uninterrupted Power Supply (UPS), power supply of a computer and other electronic equipment, etc. These wasted components can be arranged together to form a good solution with an interesting output power. The second part of this thesis presents the modelling of the power stage of three-phase induction machine as a single-phase induction generator by using one phase for excitation while the other two phases are connected in series to supply load, named "Excited Induction Generator (EIG)". Capacitor banks are added to EIG for compensating the reactive power. Capacitor values influence poles and zeros locations which are described and analyzed in the root locus according to the parameter variations. The third part of this thesis is devoted to onsite modelling of losses in induction machine. The method should achieve results simply, rapidly, without any prior information on the machine, in order to further integrate this model into energy optimization algorithms. Design of experiments is a good candidate. Experimental models of the total loss (iron loss and rotor copper losses) are proposed for motor operation and generator mode for different machines of different powers. The last part of this thesis describes output voltage/current response for both simulation results and experimental results of the induction generators. Proportional-integral and proportional-resonant controllers are tested. The implementation of closed loop controller is first achieved in an analog circuit and then, with dSPACE/MATLAB Simulink environment
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Cad, Marcelo Machado. "Estratégias de modelagem dinâmica e simulação computacional do motor de indução trifásico." Universidade de São Paulo, 2000. http://www.teses.usp.br/teses/disponiveis/18/18133/tde-13032002-113426/.
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Nesse trabalho procede-se a modelagem e simulação do motor de indução trifásico considerando-se as notações trifásicas, ortogonais, vetoriais e complexas, mos-trando seus equacionamentos e também o resultado das simulações. Para a simulação foram usados alguns programas de domínio da área acadêmica, comparando seus desempenhos quanto à apresentação de resultados e também tempo de processamen-to. Este trabalho apresenta também, um enfoque para o método de simulação do mo-tor de indução trifásico utilizando a notação vetorial complexa, o qual é baseado na notação vetorial do motor de indução que é caracterizado por grandezas complexas. Essa técnica é obtida através de simples manipulações das equações vetoriais do modelo do motor de indução compondo uma equação de estado complexa. Com o auxílio do programa Matlab, consegue-se simular o motor de indução trifásico sem a necessidade de separar os termos complexos em duas equações reais, relativas as partes real e imaginária. O que além de simplificar o procedimento de simulação também contribui para a construção do diagrama de blocos para poder entender melhor o comportamento do modelo estudado. São apresentadas no final do trabalho, as conclusões obtidas e, também, sugestões tanto para continuação do trabalho, quanto novas linhas de pesquisas.In this work it is carried out the modelling and simulation of the three-phase induction motor. It's considered three-phase, orthogonal, vectorial and complex notations, showing the different model equations and the result of the computational simulations. For the simulation it was used different softwares of the academic area, and its results and computational performance are compared. This work gives em-phasis to in new modelling procedure by using complex vector notation. This new method is based on the vectorial notation of the induction motor, which is characterized by complex entities. Through simple manipulations of complex vector equation of the dynamic induction motor equation, it is possible to compose a complex space-state equation. This complex model come be solved with Matlab software without the separation of its complex terms in two real equations. Other advantage of the complex model is the simplifying the simulation procedure and the possibilities of the blocks diagram representation. The final conclusions and suggestions for con-tinuation are presented in the end of work.
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Yan, Xiu Tan. "Graphical modelling of modular machines." Thesis, Loughborough University, 1992. https://dspace.lboro.ac.uk/2134/25290.
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This research is aimed at advancing machine design through specifying and implementing (in "proof of concept" form) a set of tools which graphically model modular machines. The tools allow mechanical building elements (or machine modules) to be selected and configured together in a highly flexible manner so that operation of the chosen configuration can be simulated and performance properties evaluated. Implementation of the tools has involved an extension in capability of a proprietary robot simulation system. This research has resulted in a general approach to graphically modelling manufacturing machines built from modular elements. A focus of study has been on a decomposition of machine functionality leading to the establishment of a library of modular machine primitives. This provides a useful source of commonly required machine building elements for use by machine designers. Study has also focussed on the generation of machine configuration tools which facilitate the construction of a simulation model and ultimately the physical machine itself. Simulation aspects of machine control are also considered which depict methods of manipulating a machine model in the simulation phase. In addition methods of achieving machine programming have been considered which specify the machine and its operational tasks. Means of adopting common information data structures are also considered which can facilitate interfacing with other systems, including the physical machine system constructed as an issue of the simulation phase. Each of these study areas is addressed in its own context, but collectively they provide a means of creating a complete modular machine design environment which can provide significant assistance to machine designers. Part of the methodology employed in the study is based on the use of the discrete event simulation technique. To easily and effectively describe a modular machine and its activity in a simulation model, a hierarchical ring and tree data structure has been designed and implemented. The modularity and reconfigurability are accommodated by the data structure, and homogeneous transformations are adopted to determine the spatial location and orientation of each of the machine elements. A three-level machine task programming approach is used to describe the machine's activities. A common data format method is used to interface the machine design environment with the physical machine and other building blocks of manufacturing systems (such as CAD systems) where systems integration approaches can lead to enhanced product realisation. The study concludes that a modular machine design environment can be created by employing the graphical simulation approach together with a set of comprehensive configuration. tools. A generic framework has been derived which outlines the way in which machine design environments can be constructed and suggestions are made as to how the proof of concept design environment implemented in this study can be advanced.
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Jayanthi, Surendran Nair Jayasoorya. "MODELLING AND ANALYSING COLLABORATING HEAVY MACHINES." Thesis, Mälardalens högskola, Akademin för innovation, design och teknik, 2017. http://urn.kb.se/resolve?urn=urn:nbn:se:mdh:diva-36719.
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Flack, Timothy John. "Induction motor modelling using finite elements." Thesis, Imperial College London, 1990. http://hdl.handle.net/10044/1/7405.
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Ardjmandpour, Negah. "Modelling and Inversion of Array Induction tool." Thesis, Imperial College London, 2010. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.522875.
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Bubic, F. R. (Frank Ranko). "Dynamic modelling, design and control of biorobotic machines." Thesis, McGill University, 1997. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=37699.
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An original way to define, analyze and design mechanical systems with inherently lifelike dynamic properties is presented. The construction of robotic manipulators which embody a complete set of technologically relevant biological principles is outlined. The ultimate objective is to develop a new class of mobile, autonomous, and interactive machines which dynamically emulate live musculoskeletal systems.This study introduces the mathematical models and algorithms to transform and synthesize the results of research in musculoskeletal physiology into explicit engineering design specifications. The application of a new contractile muscle-like viscoelastic motor, as a servomechanical drive for articulated rigid link mechanisms as well as for a novel flexible trunk-like manipulator, is investigated. Key features of the neuromuscular force control by twitch summation are combined to formulate a pulse stream control method suitable for fluid powered mechanisms.
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Abebe, K. D. "Modelling and implementation of PMW-fed asynchronous machines." Thesis, University of Strathclyde, 1987. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.382322.
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Gaude-Fugarolas, Daniel. "Modelling of transformations during induction hardening and tempering." Thesis, University of Cambridge, 2002. https://www.repository.cam.ac.uk/handle/1810/218539.
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There are many circumstances in industry where steel components are locally heated into the austenite phase field, and then quenched rapidly to produce a hardened region. Induction hardening is one such process used widely in the manufacture of automobile components, in particular to enhance the wear and contact-fatigue resistance of rubbing surfaces.
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Willoughby, Benjamin. "Modelling and simulating a three-phase induction motor." Thesis, Willoughby, Benjamin (2014) Modelling and simulating a three-phase induction motor. Other thesis, Murdoch University, 2014. https://researchrepository.murdoch.edu.au/id/eprint/23525/.
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This project involves modelling and simulating a real three-phase induction motor to determine its transient and steady-state characteristics, such as its torque-speed characteristics, torque-time characteristics, speed-time characteristics and its rotor and stator currents. For the simulation the computer program MATLAB/Simulink was used. The motors equivalent circuit parameters were determined by performing the standard equivalent circuit parameter tests; the DC test, no-load test and the blocked-rotor test. The moment of inertia of the motor was attempted to be determined through power and deceleration tests, although the method proposed in this paper proved to be unsuccessful. The resulting equivalent circuit parameters determined from the suggested tests were highly unlikely for the 0.37 kW motor used, however the MATLAB/Simulink computer program proved to be a suitable program to simulate three-phase induction motors.
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Banejad, Mahdi. "Identification of damping contribution from power system controllers." Thesis, Queensland University of Technology, 2004. https://eprints.qut.edu.au/15851/1/Mahdi_Banejad_Thesis.pdf.
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With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.
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Banejad, Mahdi. "Identification of Damping Contribution from Power System Controllers." Queensland University of Technology, 2004. http://eprints.qut.edu.au/15851/.
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With the growth of power system interconnections, the economic drivers encourage the electric companies to load the transmission lines near their limits, therefore it is critical to know those limits well. One important limiting issue is the damping of inter-area oscillation (IAO) between groups of synchronous machines. In this Ph.D. thesis, the contribution of power system components such as load and static var compensators (SVC) that affect the IAO of the power system, are analysed. The original contributions of this thesis are as follows: 1-Identification of eigenvalues and mode shapes of the IAO: In the first contribution of this thesis, the eigenvalues of the IAO are identified using a correlation based method. Then, the mode shape at each identified resonant frequency is determined to show how the synchronous generators swing against each other at the specific resonant frequencies. 2-Load modelling and load contribution to damping: The first part of this contribution lies in identification of the load model using cross-correlation and autocorrelation functions . The second aspect is the quantification of the load contribution to damping and sensitivity of system eigenvalues with respect to the load. 3- SVC contribution to damping: In this contribution the criteria for SVC controller redesign based on complete testing is developed. Then the effect of the SVC reactive power on the measured power is investigated. All of the contributions of this thesis are validated by simulation on test systems. In addition, there are some specific application of the developed methods to real data to find a.) the mode shape of the Australian electricity network, b.) the contribution of the Brisbane feeder load to damping and c.) the effect of the SVC reactive power of the Blackwall substations on the active power supplying Brisbane.
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Stuikys, Aleksas. "Electromagnetic modelling of switched reluctance machines exploiting flux tubes." Thesis, University of Southampton, 2018. https://eprints.soton.ac.uk/420946/.
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A new and computationally efficient algorithm for the design and analysis of switched reluctance machines is proposed. At the heart of the rapid analysis and design methodology is the reduced order computational method based on a flux tube model which has been refined, extended and formalised. The new flux tube method is a combination and important extension of the existing flux tubes and tubes-and-slices modelling techniques used for quantifying magnetic fields in electromechanical devices. The new method is applied to translating and rotating switched reluctance machine topologies in order to obtain the flux-linkage maps for the machines. Original analytically derived numerical error analysis of the improved flux tube method is presented which shows that the numerical accuracy afforded by the method is high despite the fact that the method is classed as a reduced order computational method. It is demonstrated how the improved model enables consistent and accurate analysis and design optimization of switched reluctance machines. The new technique is also validated against finite element simulation results. Instead of manually laborious geometry based analytical derivations; an automatic generation of cubic splines is introduced to model the magnetic flux using the improved flux tube method. The improved flux tube method exploits cubic-spline approximations for construction of constant flux lines in the magnetic and non-magnetic parts of electromechanical devices. To make the magnetic field modelling of the devices practical the saturation effects of ferromagnetic materials are included in the cubic-spline based flux tube method. Furthermore, the new flux tube method enables, in principle, the modelling of the magnetic leakage flux effects that are important from the machine performance results accuracy point of view. It is shown that in order to account for the leakage flux effects it is necessary to assume and construct probable, yet representative, leakage flux paths which are not known beforehand. An argument is put forward to support the assumption that the assumed probable leakage flux paths, even if approximate, will accurately account for the majority of leakage flux effects in the device. In order to perform rapid initial design search and optimization of switched reluctance machines the improved flux tube method was combined with the genetic algorithm based multi-objective optimization. The flux-linkage functions pertinent to a particular optimized switched reluctance machine topology obtained from the improved flux tube method indicate that the method offers good accuracy compared to finite element based analysis, but with significantly improved computational efficiency. It is demonstrated that the new modelling technique can accurately capture the important magnetic saturation and leakage flux effects occurring in the modelled machine parts. Furthermore, the new flux tube method is seen to be computationally efficient and reduces ambiguity and number of parameters used to define flux tubes in the electromagnetic devices. Pareto fronts obtained from the multi-objective genetic algorithm based optimization of a selected number of distinct topology switched reluctance machines indicate that the new flux tube method leads to the accurate and consistent estimation of these Pareto fronts. The proposed analysis and design approach based on flux tubes is applicable to translating and rotating switched reluctance machines of various topologies and therefore enables rapid design search and optimization of novel topologies.
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Chong, Yew Chuan. "Thermal analysis and air flow modelling of electrical machines." Thesis, University of Edinburgh, 2015. http://hdl.handle.net/1842/10466.
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Thermal analysis is an important topic that can affect the electrical machine performance, reliability, lifetime and efficiency. In order to predict the electrical machine thermal performance accurately, thermal analysis of electrical machines must include fluid flow modelling. One of the technologies which may be used to estimate the flow distribution and pressure losses in throughflow ventilated machines is flow network analysis, but suitable correlations that can be used to estimate the pressure losses in rotor ducts due to fluid shock is not available. The aim of this work is to investigate how the rotation affects the pressure losses in rotor ducts by performing a dimensional analysis. Apart from the additional friction loss due to the effects of rotation, other rotational pressure losses that appear in a rotor-stator system are: duct entrance loss due to fluid shock and combining flow loss at the exit of the rotor-stator gap. These losses are analysed using computational fluid dynamics (CFD) methods. The CFD simulations use the Reynolds-averaged Navier Stokes (RANS) approach. An experimental test rig is built to validate the CFD findings. The investigation showed that the CFD results are consistent with the experimental results and the rotational pressure losses correlate well with the rotation ratio (a dimensionless parameter). It shows that the rotational pressure loss generally increases with the increase in the rotation ratio. At certain operating conditions, the rotational pressure loss can contribute over 50 % of the total system loss. The investigation leads to an original set of correlations for the pressure losses in air ducts in the rotor due to fluid shock which are more suitable to be applied to fluid flow modelling of throughflow ventilated machines. Such correlations provide a significant contribution to the field of thermal modelling of electrical machines. They are incorporated into the air flow modelling tool that has been programmed in Portunus by the present author. The modelling tool can be integrated with the existing thermal modelling method, lumped-parameter thermal network (LPTN) to form a complete analytical thermal-fluid modelling method.
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Powell, David James. "Modelling of high power density electrical machines for aerospace." Thesis, University of Sheffield, 2004. http://etheses.whiterose.ac.uk/15158/.
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This thesis is concerned with the electrical, thermal and mechanical modelling of electrical machines for the 'more-electric' aircraft. Two specific applications are considered viz. a permanent magnet brush less DC (BLDC) machine for an electrohydraulic actuator for a primary flight control surface, and a switched reluctance (SR) starter/generator for the HP spool of a large civil aero-engine. As a consequence of the highly variable and often hostile ambient environment and constrained available space envelope, these electrical machines can rarely be designed in isolation, with thermal and mechanical constraints often having a significant influence on the design. In view of these considerations, a transient lumped parameter thermal model has been developed for the BLDC machine, and validated by experimental measurements on a prototype machine at various stages of manufacture. Since the rotor cavity of the BLDC machine is flooded with hydraulic fluid leaking from the pump, fluid friction losses have been modelled, and validated by tests on a prototype machine. Optimisation of the BLDC machine airgap has also been investigated using analytical electromagneticlfluiddynamic modelling. Detailed investigation of the mechanical stresses in the rotor of the HP spool machine have led to the development of a novel rotor structure for SR machines which is shown to have comparable electromagnetic performance with a conventional SR machine. A specific design of SR machine is analysed in detail in terms of dynamic current waveforms and the subsequent iron losses, and its thermal performance is modelled in a representative aero-engine environment.
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Feyzi, Mohammad Reza. "Thermal modelling of deep bar induction motor at stall /." Contents and summary only, 1997. http://web4.library.adelaide.edu.au/theses/09PH/09phf435.pdf.
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Bousbaine, Amar. "An investigation into the thermal modelling of induction motors." Thesis, University of Sheffield, 1993. http://etheses.whiterose.ac.uk/1824/.
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Electric motors are the ubiquitous workhorses of the industry, working a in wide range of conditions and applications. Modern motors, designed to exact ratings using new materials improved manufacturing techniques, are now much smaller but have higher loadings. They are being operated much nearer to the point of overload then ever before. To ensure a satisfactory life span for the motor, temperature rise must be limited to safe values. A lumped parameter thermal model has been developed, which allows rapid and accurate estimation of the temperature distribution in a machine. The lumped parameter thermal model depends on the accurate knowledge of the thermal coefficients and more importantly the loss distribution. Hence the temperature time technique was implemented to investigate the iron loss density distribution. Experimental results are discussed and loss density information throughout the volume of the machine was generated. A novel method of determining the thermal coefficients employed in the heat flow equation was investigated, using the thermal lumped parameter model of a machine. Finally a 2-D finite element method was used to corroborate, or otherwise, the use of the lumped thermal network model.
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Mohamed, Abdulatif Abdusalam. "Modelling and simulation of a cycloconverter induction motor drive." Thesis, De Montfort University, 1998. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.391545.
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Troll, Clemens, Benno Schebitz, Jens-Peter Majschak, Michael Döring, Olaf Holowenko, and Steffen Ihlenfeldt. "Commissioning new applications on processing machines: Part I - process modelling." Saechsische Landesbibliothek- Staats- und Universitaetsbibliothek Dresden, 2018. http://nbn-resolving.de/urn:nbn:de:bsz:14-qucosa-233877.
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The subject of this splitted article is the commissioning of a new application that may be part of a processing machine. Considering the example of the intermittent transport of small-sized goods, for example, chocolate bars, ideas for increasing the maximum performance are discussed. Starting from an analysis, disadvantages of a conventional motion approach are discussed, and thus, a new motion approach is presented. For realising this new motion approach, a virtual process model has to be built, which is the subject of this article. Therefore, the real process has to be abstracted, so only the main elements take attention in the modelling process. Following, important model parameters are determined and verified using virtual experiments. This finally leads to the possibility to calculate useful operating speed–dependent trajectories using the process model.
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Williams, J. P. "Mathematical modelling of the dynamic characteristics of induction heating systems." Thesis, Swansea University, 1991. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.636635.
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Induction furnaces provide a cost effective, easily controlled means of heating any electrically conductive load by the process of electromagnetic induction. Such furnaces can be more efficient than their fossil fuel equivalents but rising electricity costs have led both the equipment manufacturers and users to demand even higher efficiencies. The research described in this thesis has therefore been undertaken to improve the mathematical analysis with the ultimate aim of developing more rigorous design methodologies. Studies of the mathematical equations describing the energy transfer within the furnace concluded that, due to the complexities involved in predicting magnetic flux distributions, a numerical technique must be used for their solution. The finite element method was identified as the most suitable technique but no package suitable for induction furnaces is commercially available. It was also concluded that full three dimensional analysis would not be viable for most design offices. An existing finite element code (PE2D) used for the analysis of two dimensinal electromagnetic fields was extended to cover the aspects peculiar to induction furnace design. The main development was to enable the solutions of both the magnetic field and the corresponding induced thermal field during transient heating to be obtained. Other developments included such characteristics as non-linear magneto-thermal properties, surface energy losses and optimisation of time step and excitation frequency. The developed models can be applied to two dimensional analysis in a plane normal to conductor coils and also, in some cases, in the plane of a conductor coil. A post-processor was also developed to provide concise graphical output of such information as temperature profiles, magnetic flux distributions and power densities. The models were validated by comparison with analytical examples and by comparison with experimental data obtained with the aid of a fully automated rig capable of three dimensional flux measurements. A future research program has been identified aimed at, firstly, developing the mathematical model to provide a desk top computer design package, and, secondly, extending the experimental work to provide more validation of the code, better material information and supplementary design rules.
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Lei, Ting. "Doubly-fed induction generator wind turbine modelling, control and reliability." Thesis, University of Manchester, 2014. https://www.research.manchester.ac.uk/portal/en/theses/doublyfed-induction-generator-wind-turbine-modelling-control-and-reliability(2ceb051a-a6fb-43e6-be40-a5023dae4bea).html.
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The trend of future wind farms moving further offshore requires much higher reliability for each wind turbine in order to reduce maintenance cost. The drive-train system and power electronic converter system have been identified as critical sub-assemblies that are subject to higher failure rates than the other sub-assemblies in a wind turbine. Modern condition monitoring techniques may help schedule the maintenance and reduce downtime. However, when it comes to offshore wind turbines, it is more crucial to reduce the failure rates (or reduce the stresses) for the wind turbines during operation since the harsh weather and a frequently inaccessible environment will dramatically reduce their availability once a failure happens. This research examines the mechanical, electrical and thermal stresses in the sub-assemblies of a doubly-fed induction generator (DFIG) wind turbine and how to reduce them by improved control strategies. The DFIG control system (the rotor-side and the grid-side converter control) as well as the wind turbine control system are well established. The interactions of these control systems have been investigated. This research examines several further strategies to reduce the mechanical and electrical stresses. The control system's coordination with the protection schemes (crowbar and dc-chopper) during a grid fault is presented as well. An electro-thermal model of the power converter has been developed to integrate with the DFIG wind turbine model, for the evaluation of the thermal stresses under different operating states and control schemes. The main contributions of this thesis are twofold. A first contribution is made by providing all the control loops with well-tuned controllers in a more integrated methodology. The dynamics of these controllers are determined from their mathematical models to minimize the interference between different control-loops and also to reduce the electrical transients. This thesis proposes a coordination strategy for the damping control, pitch control and crowbar protection which significantly reduces the mechanical oscillations. On the other hand, an integrated model of the wind turbine and converter electro-thermal system is established that can illustrate the performance integration with different control strategies.
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Eggleston, J. F. "Harmonic modelling of transmission systems containing synchronous machines and static convertors." Thesis, University of Canterbury. Electrical Engineering, 1985. http://hdl.handle.net/10092/6023.
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This thesis describes the modelling of the major sources of harmonic distortion in electrical transmission systems, especially those of relevance to the New Zealand power system.
The harmonics generated by the operation of a.c./d.c. convertors are modelled using an interactive algorithm. The algorithm is applied to a number of test systems and verified using a transient convertor simulation program.
A harmonic admittance matrix model of a single phase traction system is derived and used to assess the effect of propossed harmonic filters. In this case the three phase iterative algorithm had to be modified to be able to model the locomotive's single phase convertors.
Synchronous machines are modelled using a harmonic Norton equivalent, derived from the d-q axes differential equations. The case of this model yields harmonic impedances consistent with existing models and demonstrates the well known, but greatly ignored, phenomenon of harmonic conversion. The modelling of harmonic conversion is shown to significantly modify the harmonic flows under certain system conditions.
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Chen, Xiao. "Modelling and design of permanent-magnet machines for electric vehicle traction." Thesis, University of Sheffield, 2015. http://etheses.whiterose.ac.uk/11512/.
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Electrical machines with rare-earth permanent-magnets (PMs) exhibit high torque density and good efficiency over a wide operation range. However, the high cost and limited reserves of the rare-earth material makes it less sustainable to develop this machine technology for electric vehicle (EV) traction. To improve machine performance and reduce PM usage, this thesis investigates a number of issues pertinent to modelling and design of PM machines for EV traction applications. A four-wheel vehicle dynamic model is established to quantify the influence of tyre slip on machine sizing, and thus an optimum control for torque split ratio of distributed front-rear drives is realised by minimising the loss resulting from tyre slip. PM-assisted synchronous reluctance machines with fractional-slot windings are proposed to reduce PM usage whilst exploiting advantages of fractional-slot windings. To more accurately evaluate reluctance torque and thus maximise torque production of an interior PM (IPM) machine in design stage, a torque model allowing for torque component separation via frozen permeability is presented. A generic approach to magneto-motive force harmonics reduction using multiple 3-phase windings is proposed to reduce rotor iron loss and torque ripple whilst improve reluctance torque and machine efficiency. A 9- phase 18-slot 14-pole IPM machine is subsequently designed based on the proposed multiple 3-phase windings and its performance validated on a 10kW prototype. In order to accurately assess the performance of an IPM machine drive, a high-fidelity and computationally efficient machine model is proposed by considering magnetic saturation, spatial harmonics, iron loss and temperature effects. Furthermore, an electro-thermally coupled model is established by integrating the temperature-dependent electromagnetic model with a state-space lumped parameter thermal model. Both models are experimentally validated. An analytical mechanical stress model is proposed to incorporate mechanical strength constraints into machine global optimisation process. Thus, unfeasible designs whose mechanical strength cannot meet the requirement can be avoided.
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Ogidi, Oladapo Omotade. "Modelling and detection of faults in axial-flux permanent magnet machines." Doctoral thesis, University of Cape Town, 2016. http://hdl.handle.net/11427/20831.
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The development of various topologies and configurations of axial-flux permanent magnet machine has spurred its use for electromechanical energy conversion in several applications. As it becomes increasingly deployed, effective condition monitoring built on reliable and accurate fault detection techniques is needed to ensure its engineering integrity. Unlike induction machine which has been rigorously investigated for faults, axial-flux permanent magnet machine has not. Thus in this thesis, axial-flux permanent magnet machine is investigated under faulty conditions. Common faults associated with it namely; static eccentricity and interturn short circuit are modelled, and detection techniques are established. The modelling forms a basis for; developing a platform for precise fault replication on a developed experimental test-rig, predicting and analysing fault signatures using both finite element analysis and experimental analysis. In the detection, the motor current signature analysis, vibration analysis and electrical impedance spectroscopy are applied. Attention is paid to fault-feature extraction and fault discrimination. Using both frequency and time-frequency techniques, features are tracked in the line current under steady-state and transient conditions respectively. Results obtained provide rich information on the pattern of fault harmonics. Parametric spectral estimation is also explored as an alternative to the Fourier transform in the steady-state analysis of faulty conditions. It is found to be as effective as the Fourier transform and more amenable to short signal-measurement duration. Vibration analysis is applied in the detection of eccentricities; its efficacy in fault detection is hinged on proper determination of vibratory frequencies and quantification of corresponding tones. This is achieved using analytical formulations and signal processing techniques. Furthermore, the developed fault model is used to assess the influence of cogging torque minimization techniques and rotor topologies in axial-flux permanent magnet machine on current signal in the presence of static eccentricity. The double-sided topology is found to be tolerant to the presence of static eccentricity unlike the single-sided topology due to the opposing effect of the resulting asymmetrical properties of the airgap. The cogging torque minimization techniques do not impair on the established fault detection technique in the single-sided topology. By applying electrical broadband impedance spectroscopy, interturn faults are diagnosed; a high frequency winding model is developed to analyse the impedance-frequency response obtained.
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Walker, Ian. "Applications of solid modelling to component inspection with coordinate measuring machines." Thesis, University of Bath, 1991. https://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.314607.
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Claassens, Andries Johannes. "Transient modelling of induction motors in a petrochemical plant using Matlab." Thesis, Stellenbosch : Stellenbosch University, 2008. http://hdl.handle.net/10019.1/20432.
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Thesis (MScIng)--University of Stellenbosch, 2008.ENGLISH ABSTRACT: The behaviour of induction motors at a petrochemical plant under transient conditions was investigated with the view to improve plant immunity to voltage fluctuations. The benefits of using a phase-variable induction motor model rather than the simpler d-q models usually employed are investigated. A simplified model of the plant electrical distribution system was derived. Phase variable and d-q induction motor models were implemented as well as a synchronous generator model. Practical considerations precluded the use of commercial software for the simulation of transient conditions and a basic simulation program was developed using Matlab to evaluate the behaviour of the dynamic machine models and distribution system. It was established that the configuration of the installed re-acceleration system can be optimised to reduce the possibility of plant outages as a result of voltage fluctuations. It was found that the use of more detailed induction machine models provide valuable insight into system behaviour and is justified if accurate motor parameters are available or can be estimated. The simplified plant model yielded useful results and enabled the identification of incorrect system data. The investigation showed that Matlab is suitable for the rapid development of a basic transient simulation program that can be used to study the behaviour of different interconnected dynamic machine models.
AFRIKAANSE OPSOMMING: Die gedrag van induksiemotors in 'n petrochemiese aanleg onder oorgangstoestande is ondersoek ten einde die immuniteit van die aanleg vir spanningsfluktuasies te verbeter. Die voordele van die gebruik van 'n fase-veranderlike induksiemotor model eerder as die eenvoudiger d-q modelle wat normaalweg gebruik word is ondersoek. 'n Vereenvoudigde model van die aanleg se elektriese distribusiestelsel is afgelei. Faseveranderlike en d-q induksiemotor modelle is geimplementeer sowel as 'n sinkroongenerator model. Praktiese oorwegings het die gebruik van kommersiële programmatuur vir die simulasie van oorgangstoestande verhoed en 'n basiese program is in Matlab ontwikkel om die gedrag dinamiese masjienmodelle en die distribusiestelsel te evalueer. Daar is vasgestel dat die konfigurasie van die geinstalleerde herversnellerstelsel geoptimeer kan word om die moontlikheid van aanleg onderbrekings as gevolg van spanningsfluktuasies te verminder. Daar is gevind dat die gebruik van meer gedetaileerde induksiemasjien modelle waardevolle insig in die gedrag van die stelsel lewer en geregverdig is indien akkurate motorparameters beskikbaar is of afgeskat kan word. Die vereenvoudigde model van die aanleg het bruikbare resultate gelewer en die het die identifikasie van foutiewe stelseldata moontlik gemaak. Die ondersoek het getoon dat Matlab geskik is vir die snelle ontwikkeling van 'n basiese oorgangsimulasie program wat gebruik kan word om die gedrag van verskillende gekoppelde dinamiese masjienemodelle te bestudeer.
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Fahmi, Nagi R. "Modelling of induction motors for system faults and transient stability studies." Thesis, Aston University, 1986. http://publications.aston.ac.uk/8049/.
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The research carried out in this thesis was mainly concerned with the effects of large induction motors and their transient performance in power systems. Computer packages using the three phase co-ordinate frame of reference were developed to simulate the induction motor transient performance. A technique using matrix algebra was developed to allow extension of the three phase co-ordinate method to analyse asymmetrical and symmetrical faults on both sides of the three phase delta-star transformer which is usually required when connecting large induction motors to the supply system. System simulation, applying these two techniques, was used to study the transient stability of a power system. The response of a typical system, loaded with a group of large induction motors, two three-phase delta-star transformers, a synchronous generator and an infinite system was analysed. The computer software developed to study this system has the advantage that different types of fault at different locations can be studied by simple changes in input data. The research also involved investigating the possibility of using different integrating routines such as Runge-Kutta-Gill, RungeKutta-Fehlberg and the Predictor-Corrector methods. The investigation enables the reduction of computation time, which is necessary when solving the induction motor equations expressed in terms of the three phase variables. The outcome of this investigation was utilised in analysing an introductory model (containing only minimal control action) of an isolated system having a significant induction motor load compared to the size of the generator energising the system.
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Del, Villar René. "Modelling and simulation of Brunswick mining grinding circuit." Thesis, McGill University, 1985. http://digitool.Library.McGill.CA:80/R/?func=dbin-jump-full&object_id=72758.
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Wu, Lijian. "Analytical modelling of electromagnetic performance and parasitic effects of permanent magnet machines." Thesis, University of Sheffield, 2012. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.647997.
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Zhao, Xiaoming. "Modelling of the mass transfer and fluid flow in package dyeing machines." Thesis, Heriot-Watt University, 2004. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.580623.
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The property of flow and the transfer of dye through the yarn assembly in a package dyeing process is modelled and simulated to provide a kinetic understanding of the package dyeing process. A novel approach to the modelling of flow in porous media and dye transfer through the package has been presented. The flow properties in package dyeing process have been described by coupling the Navier-Stokes equations with Brinkman equations. The Navier-Stokes equations were also combined with Darcy's law for comparison. The dye concentration in dyebath and on fibres throughout the package has been defined by the mass transfer model, which involved the factors of dispersion, convection, and various adsorption isotherms. The simulation results of the flow model present the velocity and pressure distribution of the flow in the tube and yam assembly. The influence of package factors, such as package size, shape, density, and process parameters, such as flow rate, flow direction, dye/fibre type, and dye concentration in the mixing tank on the outcome of the dyeing process have been examined based on the mass transfer model. The relevant adsorption isotherms can be selected for different dye/fibre combinations, to simulate the dye dispersion process through the package. The relationship between various dye dosing profiles and the degree of levelness achieved is also demonstrated. The use of computational methods to simulate the dyeing process is proved to be a powerful tool providing a kinetic understanding of the flow phenomena and dye transfer in package dyeing process. The predicted behaviour of the liquor flow in both tube and porous package, as well as the dye concentration distributions across the package under different conditions, appear to be in qualitatively good agreement with available experimental data. These models can also be used to design package dyeing apparatus, and select suitable material for the construction of tubes taking into account the static pressure predictions under different flow rates. The selection of correct type of flow meter, and pressure sensors based on their simulated range can also be carried out.
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Wyllie, Peter Bruce. "Electrothermal modelling for doubly fed induction generator converter reliability in wind power." Thesis, Durham University, 2014. http://etheses.dur.ac.uk/10902/.
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Increased reliance upon renewable energy sources, chiefly wind, places a growing emphasis on the reliability of the technology used in Wind Turbines. The current Wind Turbine fleet is dominated by the Doubly Fed Induction Machine WT, which utilises a partially rated power electronic converter to vary the speed of the rotor and thus ensure the maximum energy capture available from the wind. This converter is associated with a significant percentage of WT failures. This thesis examines the low frequency temperature cycling occurring in one half of the back to back converter which results in a high failure rate of the rotor side converter as compared to the grid side converter. To this end a MATLAB/PLECS model was constructed to demonstrate the temperature cycling occurring in a 2.5MW DFIG WT. Lifetime of the semiconductor devices was extrapolated. An adaptation to the standard Maximum Power Point Tracking control method was suggested in which the lowest operating frequencies (less than 2.33Hz) were avoided. In doing so, lifetime was observed to increase at a minor cost to energy yield from the WT.
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Hussain, Tanweer. "Modelling and controlling variation propagation in mechanical assembly of high speed rotating machines." Thesis, University of Nottingham, 2012. http://eprints.nottingham.ac.uk/28465/.
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Assembly plays a vital role in the quality of a final product and has a great impact on the manufacturing cost. The mechanical assemblies consist of parts that inevitably have variations from their ideal dimensions. These variations propagate and accumulate as parts are assembled together. Excessive amount of variations in an assembly may cause improper functionality of the product being assembled. Improving assembly quality and reducing the assembly time and cost are the main objectives of this thesis. The quality of an assembly is determined in terms of variations in critical assembly dimensions, also known as Key Characteristics (KCs). Key Characteristics are designated to indicate where excess variation will affect product quality and what product features and tolerances require special attention. In order to improve assembly quality and reduce assembly time and cost, it is necessary to: (1) model non-ideal parts based on tolerances defined in design standards or current industrial practice of component inspection, (2) model assemblies and their associated assembly processes to analyse tolerance stack-up in the assembly, (3) develop probabilistic model to predict assembly variation after product assembly, and (4) implement control strategies for minimising assembly variation propagations to find optimum configuration of the assembly. Two assembly models have been developed, a linear model and a fully non-linear model for calculating assembly variation propagations. The assembly models presented in this thesis also allows for inclusion of geometric feature variation of each assembly component. Methods of incorporating geometric feature variations into an assembly variation model are described and analysis techniques are explained. The assembly variation model and the geometric variation models have been developed for 20 and 3D assemblies. Modelling techniques for incorporating process and measurement noise are also developed and described for the nonlinear assembly model and results are given to demonstrate the calculation of assembly variations while considering part, process and measurement errors. Two assembly case studies originating in sub-assemblies of aero-engines have been studied: Case Study 1, representing the rotating part (rotor) of an aero-engine, and Case Study 2, representing non-rotating part (stator) of an aero-engine. A probabilistic method based on the linear model is presented as a general analytical method for analysis of 3D mechanical assemblies. Probability density functions are derived for assembly position errors to analyse a general mechanical assembly, and separate probability functions are derived for the Key Characteristics (KCs) for assembly in Case Studies 1 and 2. The derived probability functions are validated by using the Monte Carlo simulation method based on the exact (full non-linear) model. Results showed that the proposed probabilistic method of estimating tolerance accumulation in mechanical assemblies is very efficient and accurate when compared to the Monte Carlo simulation method, particularly if large variations at the tails of the distributions are considered. Separate control strategies have been implemented for each case study. Four methods are proposed to minimise assembly variations for Case Study 1, and one error minimisation method is suggested for assemblies of Case Study 2. Based on the developed methods to optimise assembly quality, the two case studies were investigated, and it was found that the proposed optimisation methods can significantly improve assembly quality. The developed optimisation methods do not require any special tooling (such as fixtures) and can easily be implemented in practice.
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Taras, Petrica. "Investigation on multi-physics modelling of fault tolerant stator mounted permanent magnet machines." Thesis, University of Sheffield, 2018. http://etheses.whiterose.ac.uk/22449/.
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This thesis investigates the stator mounted permanent magnet machines from the point of view of fault tolerant capability. The topologies studied are switched flux (and its derivatives C-Core, E-Core and modular), doubly salient and flux reversal permanent magnet machines. The study focuses on fault mode operation of these machines looking at severe conditions like short-circuit and irreversible demagnetization. The temperature dependence of the permanent magnet properties is taken into account. A complex multi-physics model is developed in order to assess the thermal state evolution of the switched flux machine during both healthy and faulty operation modes. This model couples the electro-mechanical domain with the thermal one, thus being able to consider a large range of operating conditions. It also solves issues such as large computational time and resources while still maintaining the accuracy. Experimental results are also provided for each chapter. A hierarchy in terms of fault tolerant capability is established. A good compromise can be reached between performance and fault tolerant capability. The mechanism of the magnet irreversible demagnetization process is explained based on magnetic circuit configuration. It is also found that the studied topology are extremely resilient against the demagnetizing influence of the short-circuit current and the magnet demagnetization is almost only affected by temperature.
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Alzamil, Ibrahim Ali M. "Energy-aware profiling and prediction modelling of virtual machines in cloud computing environments." Thesis, University of Leeds, 2017. http://etheses.whiterose.ac.uk/17243/.
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Cloud Computing has changed the way in which individuals and businesses use IT resources. Instead of buying their own IT resources, they can use the Cloud services offered by Cloud providers with reasonable costs based on a “pay-per-use” model. With the wide adoption of Cloud Computing, the costs for maintaining the Cloud infrastructure have become a vital issue for the providers, especially with the large amount of energy being consumed to operate these resources. Hence, the excessive use of energy consumption in Cloud infrastructures has become one of the major cost factors for Cloud providers. In order to reduce the energy consumption and enhance the energy efficiency of Cloud resources, proactive and reactive management tools are used with consideration of physical resources’ energy consumption. However, these tools need to be supported with energy-awareness not only at the physical machine (PM) level but also at virtual machine (VM) level in order to make enhanced energy-aware decisions. As the VMs do not have physical interface, identifying the energy consumption at the VM level is difficult and not directly measured. This thesis introduces an energy-aware Cloud system architecture that aims to enable energy-awareness at the deployment and operational levels of a Cloud environment. At the operational level, an energy-aware profiling model is introduced to identify energy consumption for heterogeneous and homogeneous VMs running on the same PM based on the size and CPU utilisation of each VM. At the deployment level, an energy-aware prediction framework is introduced to forecast future VMs’ energy consumption. This framework first predicts the VMs’ workload based on historical workload patterns, particularly static and periodic, using Auto-regressive Integrated Moving Average (ARIMA) model. The predicted VM workload is then correlated to the physical resources within this framework in order to get the predicted VM energy consumption. The evaluation of the proposed work on a real Cloud testbed reveals that the proposed energy-aware profiling model is capable of fairly attributing the physical energy consumption to homogeneous and heterogeneous VMs, therefore enabling energy-awareness at the VM level. Compared with actual results obtained in this testbed, the predicted results show that the proposed energy-aware prediction framework is capable of forecasting the energy consumption for the VMs with a good prediction accuracy for static and periodic Cloud application workload patterns. The application of the proposed work is providing energy-awareness which can be used and incorporated by other reactive and proactive management tools to make enhanced energy-aware decisions and efficiently manage the Cloud resources. This can lead towards a reduction of energy consumption, and therefore lowering the cost of operational expenditure (OPEX) for Cloud providers and having less impact on the environment.
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Krause, Anna [Verfasser]. "Variation-aware behavioural modelling using support vector machines and affine arithmetic / Anna Krause." Hannover : Gottfried Wilhelm Leibniz Universität Hannover, 2019. http://d-nb.info/1204458952/34.
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Chen, Liang. "Modelling and design optimisation of permanent magnet machines for electric vehicle traction applications." Thesis, University of Sheffield, 2016. http://etheses.whiterose.ac.uk/16962/.
Full textAbstract:
While the fuel resource scarcity and the environment crisis are becoming two of the major problems for the human society in the new century, in the context that the on-road transport is the largest energy-consuming society sector, electrical vehicles (EVs) serving resource-sustainable environmentally-clean transport attract increasing attention. Permanent magnet (PM) traction machines with high torque and power densities, and high energy efficiency gain great interest from the engineer and industry communities. Jointly with the chances, fresh challenges are brought by EVs to PM machine designers. In response to the vehicles' call for high speed, mighty acceleration, long range, safe and robust system, the engineers need to develop a powerful design platform that allows for multi-physic evaluations of machine designs over a large torque-speed range, especially for energy efficiency, PM health, and thermal-withstanding ability. More importantly, these evaluations must be against driving cycles rather than on a single rated operation point in catering to various real-world driving conditions. The complex and enormous computation efforts required necessitate new, effective and feasible design techniques. In this work a set of modelling techniques for PM machines are developed, in order to establish a computationally-efficient yet accurate design and optimisation method for EV traction PM machines. Through the method, comprehensive machine multi-physics assessments against driving cycles are enabled; electro-thermally coupled evaluation is achieved; 3-dimensional eddy-current loss of PMs are accurately monitored in the context of PM protection; lastly with the techniques integrated together, a fast and effective optimisation method for EV traction PM machines is acquired. To exploit the benefits of the proposed method, a design, optimisation and manufacture process of PM machines for a light-duty EV distributed traction system is formatted, which includes a quantity assessment of machine topologies, investigation of driving cycle influence on designs, optimisation of the selected 18-slot 8-pole interior PM machine against a series of EV machine design criteria, the subsequent prototype experiments, and optimisation of combinations and power split ratios of PM machines for the distributed traction system. Through the design process for the EV traction system and experiments, the effectiveness, computational efficiency, and accuracy of the proposed designing methods are exhibited and validated.
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Femminella, Oliver Paul. "Neurofuzzy and SUPANOVA modelling of the processing-property relationships of aerospace Al-alloys." Thesis, University of Southampton, 2000. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.324770.
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