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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
31

Estratégias de modelagem dinâmica e simulação computacional do motor de indução trifásico. / Strategies of dynamic modelling and computational simulation of the three-phase induction motor.

Cad, Marcelo Machado 07 August 2000 (has links)
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 software’s 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.
32

Incipient Bearing Fault Detection for Electric Machines Using Stator Current Noise Cancellation

Zhou, Wei 14 November 2007 (has links)
The objective of this research is to develop a bearing fault detection scheme for electric machines via stator current. A new method, called the stator current noise cancellation method, is proposed to separate bearing fault-related components in the stator current. This method is based on the concept of viewing all bearing-unrelated components as noise and defining the bearing detection problem as a low signal-to-noise ratio (SNR) problem. In this method, a noise cancellation algorithm based on Wiener filtering is employed to solve the problem. Furthermore, a statistical method is proposed to process the data of noise-cancelled stator current, which enables bearing conditions to be evaluated solely based on stator current measurements. A detailed theoretical analysis of the proposed methods is presented. Several online tests are also performed in this research to validate the proposed methods. It is shown in this work that a bearing fault can be detected by measuring the variation of the RMS of noise-cancelled stator current by using statistical methods such as the Statistical Process Control. In contrast to most existing current monitoring techniques, the detection methods proposed in this research are designed to detect generalized-roughness bearing faults. In addition, the information about machine parameters and bearing dimensions are not required in the implementation.
33

Estratégias de modelagem dinâmica e simulação computacional do motor de indução trifásico. / Strategies of dynamic modelling and computational simulation of the three-phase induction motor.

Marcelo Machado Cad 07 August 2000 (has links)
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 software’s 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.
34

Modélisation électro-mécanique de transmissions par engrenages : Applications à la détection et au suivi des avaries / Electromechanical modeling of motor-gear units : Applications to the detection and monitoring of gear tooth faults

Feki, Nabih 30 May 2012 (has links)
La détection et le diagnostic des défauts d’engrenages ont été traditionnellement basés sur l'analyse des signaux vibratoires et acoustiques. Mais, ces méthodes peuvent être coûteuses suite aux difficultés techniques de mise en œuvre de capteurs sur des pièces en rotation. Dans ces travaux de thèse, une méthode originale de détection de défauts locaux dans des engrenages entraînés par des moteurs électriques est proposée en se basant sur le suivi des courants statoriques. Le système électromécanique est simulé numériquement en combinant un modèle électrique dynamique de moteurs asynchrones (modèle de Kron et modèle des réseaux de perméances) et un modèle mécanique dynamique d’engrenages droits et hélicoïdaux incluant les arbres et les paliers. Certains défauts classiques du moteur (excentricité du rotor) et des défauts d'engrenages (écaillages sur les flancs actifs de dentures) sont considérés et une technique itérative de résolution est présentée qui permet de résoudre le problème électromécanique couplé. De nombreux résultats sont présentés qui illustrent la possibilité et la sensibilité de détection de défauts d’engrenages par mesure de courants électriques sur le moteur. Sur la base de ces simulations, il est conclu que l’analyse de la signature des courants du moteur apparaît comme une méthode suffisamment précise pour détecter et surveiller les défauts locaux d’engrenage comme les écaillages. / The fault diagnosis in geared transmissions has been traditionally based on vibration monitoring but the implementation of sensors can be expensive and, in some applications, present technical difficulties. In this thesis, an original way of detecting faulty gears driven by electrical motors is proposed based on the monitoring of the motor currents. The corresponding electromechanical coupled system is numerically simulated by combining i) an electrical dynamic model of asynchronous motors (Kron’s model and permeance network model) and ii) a mechanical dynamic model of spur and helical gears (3D lumped parameter model) including the shafts and bearings. Some classic motor defects (rotor eccentricity) and gear faults (tooth spalls) are considered and an iterative solution technique is presented which makes it possible to solve the coupled electromechanical problem. A number of results are presented, which illustrate the possibility of tooth fault detection by stator current measurements with regard to the position and dimensions of the defect. Based on these simulations, it is concluded that motor current signature analysis can be a viable tool for the detection of localized gear faults such as tooth pitting.
35

Conception de machines à aimants permanents à haute densité de couple pour les éoliennes de forte puissance / Design of high torque density permanent magnet machine for high power wind turbine

Mouty, Stéphane 30 May 2013 (has links)
Les directives européennes visant à produire 20% de l’énergie à base de sources renouvelables imposent aux gouvernements d’investir dans de nouveaux moyens de production. Un bilan du marché de l’énergie sera réalisé et permettra de montrer la part des énergies renouvelables dans la consommation d’énergie. Après les moyens de conversion de l’énergie hydraulique, les éoliennes sont les systèmes, utilisant une source renouvelable, les plus rencontrées. Les objectifs fixés ont conduit à s’intéresser à l’installation d’éoliennes en mer. Les contraintes spécifiques rencontrées ont poussé les acteurs du marché à développer de nouveaux systèmes et donc des alternateurs adaptés : utilisation des aimants permanents et de l’attaque directe. La modélisation des machines à aimants permanents est décrite. Une topologie classique est d’abord présentée. D’autres solutions seront ensuite étudiées dans le but d’augmenter les densités de couple. L’une d’elles est la machine à bobinage à pas fractionnaire qui permet d’éviter les enchevêtrements des têtes de bobines. D’autre part, l’utilisation de systèmes polyphasés, permettant d’augmenter la disponibilité des systèmes en autorisant des fonctionnements en modes dégradés, est un moyen intéressant afin d’être en présence de systèmes plus fiables. La démarche, qui a permis d’effectuer le choix du dimensionnement de la génératrice pour répondre au mieux à l’appel d’offre d’un client, est présentée ainsi que les résultats des essais réalisés sur les prototypes. Au final, l’éolienne qui est équipée de cet alternateur a une puissance massique qui est au moins 15% plus importante que les solutions disponibles en 2013 sur le marché. / Given the European guidelines, which consist into producing 20% of the energy from renewable sources, the governments are obliged to invest in new types of production systems. An energy market survey will show the part of renewable energy in the energy consumption. After the hydroelectric systems, the wind turbines are the most common systems using renewable sources. The current objectives have led to consider the installation of offshore wind turbine. The specific limitations led the market players to develop new systems with adapted generators: direct drive permanent magnet generator. Model of the permanent magnet machines is described. First a conventional machine topology is presented, then other solutions will be studied with the objective of increasing the torque density. One of them is the concentrated winding machines where the end winding overlapping is avoided. On the other hand, use multiphase system becomes very interesting in order to increase system reliability and work in fault tolerant modes. The strategy that was adopted for the design of the generator to fit the best the specification is also discussed as well as the results of the tests. At the end, the wind turbine equipped with this alternator, has a power density at least 15% higher than the 2013’s available solutions.
36

Vysokootáčkový synchronní stroj s vnějším rotorem / High-speed outer rotor synchronous machine

Král, Radek January 2021 (has links)
The master thesis deals with the construction and design of a high-speed synchronous machine with an outer rotor. The thesis is organised into three main chapters. The first chapter deals with machine design theory as well as mechanical limits, which are significant for high speed machines. This chapter also provides examples of applications of these electrical machines. In the second chapter, the initial design of the machine is calculated analytically. This machine design is optimised and the third chapter of this work shows the results of simulations using the finite elements method, including the evaluation of these results.
37

A Heterogeneous Multirate Simulation Approach for Wide-bandgap-based Electric Drive Systems

Olatunji T Fulani (9581096) 27 July 2021 (has links)
<p>Recent developments in semiconductor device technology have seen the advent of wide-bandgap (WBG) based devices that enable operation at high switching frequencies. These devices, such as silicon carbide (SiC) metal-oxide-semiconductor field-effect transistors (MOSFETs), are becoming a favored choice in inverters for electric drive systems because of their lower switching losses and higher allowable operating temperature. However, the fast switching of such devices implies increased voltage edge rates (high <i>dv/dt</i>) that give rise to various undesirable effects including large common-mode currents, electromagnetic interference, transient overvoltages, insulation failure due to the overvoltages, and bearing failures due to</p> <p>microarcs. With increased use of these devices in transportation and industrial applications, it is imperative that accurate models and efficient simulation tools, which can predict these high-frequency effects and accompanying system losses, be established. This research initially focuses on establishing an accurate wideband model of a surface-mount permanent-magnet</p> <p>ac machine supplied by a WBG-based inverter. A new multirate simulation framework for predicting the transient behavior and estimating the power losses is then set forth. In this approach,</p> <p>the wideband model is separated into high- and low-frequency models implemented using two different computer programs that are best suited for the respective time scales. Repetitive execution of the high-frequency model yields look-up tables for the switching losses in the semiconductors, electric machine, and interconnecting cable. These look-up tables are then incorporated into the low-frequency model that establishes the conduction</p> <p>losses. This method is applied to a WBG-based electric drive comprised of a SiC inverter and permanent-magnet ac machine. Comparisons of measured and simulated transients are provided.</p>
38

Étude de machines électriques non conventionnelles pour des alternateurs industriels / Study of non-conventional electric machines for industrial generators

Fernandez sanchez, Alejandro 06 December 2016 (has links)
Cette thèse s’intéresse à l’analyse de structures de machines électriques non conventionnelles destinées à la production d’électricité par des groupes électrogènes. Les topologies recherchées doivent utiliser moins de matières actives et/ou simplifier la procédure de fabrication par rapport aux machines actuelles.Une des structures est dédiée au système d’excitation de la machine. Elle possède un stator à griffes avec un bobinage toroïdal. Son dimensionnement est réalisé à l’aide d’un modèle de calcul par éléments finis en 3D, qui a été validé expérimentalement. Cette structure permet d’obtenir une réduction significative de la quantité de cuivre dans le bobinage.Les deux autres structures traitées concernent l’alternateur principal. Une machine synchro-réluctante à barrières deflux et à rotor bobiné a été proposée. L’objectif est d’augmenter la densité de couple grâce au couple de saillance. Elle est dimensionnée et comparée avec la structure conventionnelle. Ce cas met en évidence les limitations des structures proches de la structure actuelle.La dernière structure est une nouvelle topologie de machine électrique. Elle combine les caractéristiques des machines à flux axial et des machines à griffes, permettant de simplifier le système d’excitation. Une approche de modélisation originale a été développée pour l’analyse de cette topologie 3D en vue de son dimensionnement par optimisation. Le système d’excitation a un rôle important dans les performances de cette machine.Cette thèse constate aussi que l’évolution future des matériaux magnétiques pourrait tirer meilleur profit des structures non-conventionnelles avec des trajets de flux tridimensionnels. / The PhD project aims to analyse nonconventional structures of electric machines for electric power generation with diesel gensets. The researched topologies should use less active materials and/or simplify the manufacturing process compared to today’s machines.One of the structures is intended for the excitation system of the electric machine. It is composed of a claw-pole stator and a toroidal winding. It is designed using a 3D Finite Element model, previously validated by a prototype. This structure allows a significant reduction of the quantity of copper of the field winding.The other two structures under study are proposed for the main generator. A synchronous-reluctance machine with flux-barriers and a field winding in the rotor is analysed. The objective is to increase the torque density by increasing the reluctance torque. The designed machine is compared to the conventional structure. This case shows the limitations of structures similar to the current structure.The last structure is a new topology of electric machine. It combines the characteristics of claw-pole machines andaxial-flux machines. An original modelling approach is developed to analyse this 3D structure for its design based on an optimization algorithm. The study shows that the excitation system has a key role in its performances.This work also notes that the future evolution of magnetic materials should benefit the use of non-conventional structures with 3D flux paths.
39

Design of a novel rotary compact power pack for the series hybrid electric vehicle. Design and simulation of a compact power pack consisting of a novel rotary engine and outer rotor induction machine for the series hybrid electric vehicle powertrain.

Amirian, Hossein January 2010 (has links)
Hybrid electric vehicles significantly reduce exhaust emissions and increase fuel economy. Power packs are the most fundamental components in a series powertrain configuration of a hybrid vehicle, which produce the necessary power to run the vehicle. The aim of this project is to design a compact power pack for a series hybrid vehicle, using virtual prototyping. The hybrid electric vehicle characteristics and configurations are analysed, followed by an explanation of the principles of induction machines. A new type of rotary induction machine with an outer rotor construction is designed to be coupled with the novel rotary internal combustion engine with rotating crankcase in order to form the compact power unit for the hybrid vehicle. The starting and generation performance of the designed machine is analysed by an electric machine simulator, called JMAG. ADVISOR software is studied and utilised to simulate the overall vehicle performance, employing different categories of power packs in the powertrain. Results show that the proposed compact power pack has the best performance in terms of fuel economy, emissions and battery charging compared to the existing power unit options. Over the city cycle, fuel economy is increased by up to 47 % with emission reduced by up to 36 % and over the highway cycle, fuel economy is increased by up to 69 % with emission reduced by up to 42 %.
40

Modeling and Control of Dual Mechanical Port Electric Machine

Cai, Haiwei January 2015 (has links)
No description available.

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