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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.
41

Evaluation des performances énergétiques d'une nouvelle génération d'éolienne off-shore / Energy performances assessment of a new generation offshore wind turbine

Kouevidjin, Modobozi 11 December 2015 (has links)
L’alternateur étudié dans cette thèse équipe une éolienne flottante à axe vertical. Il s’agit d’unemachine synchrone de 2MW, polyphasée, bobinée sur plots, à pas fractionnaire, à aimants et à prisedirecte. L’objectif majeur de la thèse est la caractérisation de cet alternateur afin d’en évaluer lesperformances. Une modélisation analytique de la perméance d'entrefer et de la force magnétomotriceont conduit à l'étude de l'induction d'entrefer dont le contenu harmonique s'est révélé êtreparticulièrement riche. La caractérisation a également porté sur la détermination des inductancespropres et mutuelles, avec un calage du modèle effectué en exploitant des mesures expérimentalesfaites à l’arrêt. La particularité de la machine étudiée nous a amené à considérer un enroulement fictiféquivalent dans le but de déterminer les inductances cycliques, nécessaires à l'établissement du schémamonophasé équivalent. De plus, le fonctionnement back to back de la machine a été étudié et simulé. Ilpermet de faire des tests de la machine elle-même mais aussi des éléments de la chaîne de conversion,sans l'utilisation d'une deuxième machine ou des pâles pour entraîner le rotor du prototype. Il offre enplus la possibilité de tester différents type de fonctionnements et d'évaluer la puissance que peutproduire la machine : différents scénario de fonctionnement ont été simulés et les paramètresnécessaires aux essais sur site ont été définis. Le fonctionnement back to back a fait l’objetd’investigation sur une machine synchrone classique. Les difficultés de fonctionnement ontnotamment pu être mises en évidence avec une modélisation analytique des phénomènesélectromagnétique qui s'y produisent et des essais expérimentaux. / The studied alternator equips a vertical axis offshore wind turbine. It is a 2MW fractional slotconcentrated winding permanent magnet synchronous polyphase machine, directly connected to bladeturbine. The principal purpose of this thesis consists in characterizing the alternator in order toevaluate its performances. The air gap permeance and the magnemotive force analytical modelingleads to study the air gap flux density and its harmonic content, which is particularly rich. Thecharacterization has also concerned the self and mutual inductance determination, which has requiredstalling the model by exploiting experimental measurements done at standstill. The particularity of thestudied machine leads us to consider an equivalent fictitious winding in order to determine the cyclicalinductances, necessary for the single-phase equivalent scheme establishment. Moreover, the machineback to back functioning has been studied and simulated. This functioning allows testing the machineitself and the other conversion chain subsystems, without using a second machine or blades to drivethe prototype rotor. It offers the possibility to test different types of operating points and to estimatethe power that can produce the studied machine: different operating points scenarios have beensimulated and parameters for tests have been defined. The back to back functioning of a classicalsynchronous machine has been also investigated, with an analytical modeling of the electromagneticphenomena and experimental tests.
42

Analýza synchronního stroje s permanentními magnety o výkonu 1,1 MW / Analysis of 1,1 MW permanent magnet synchronous motor

Homolová, Romana January 2020 (has links)
This thesis deals with the elaboration of The Permanent Magnet Synchronous Motor and the calculation of its parameters. In the first part, the construction and used permanent magnets of this motor are listed here. The next part of the thesis contains a short overview of the stator windings, the calculation of the winding factors and calculation of the basic parameters of the stator winding. The calculation of the magnetic induction in the air gap is also illustrated here. The result is recalculated by using the Carter factor and then the value of the first harmonics of air-gap flux density is determined. The result is compared with the analysis in the program FEMM. The next part of the thesis is creating a comprehensive overview of the machine using a replacement circuit diagram and phasor diagrams. Finally, the thesis contains model created in RMxprt and ANSYS Maxwell. The results of the model analysis are compared with the analytical calculation
43

Analýza magnetického pole pomocí MKP a magnetické sondy / Magnetic field analysis with finite element method and magnetic sensor

Volf, Tomáš January 2010 (has links)
The magnetic field analysis by MKP and magnetic probe project deals with magnetic field analysis of asynchronous machine cross section. This analysis is written in detail along with the necessary theory of asynchronous machine and the ANSYS program. The magnetic field of selected machine is measured by magnetic probe and results are compared with calculation. The next part of thesis is draft of device for the magnetic field analysis.
44

Návrh, optimalizace a modelování provozních stavů synchronního stroje s permanentními magnety na rotoru / Design, optimization and full load circuit simulation of the surface mounted permanent magnet machine

Bláha, Martin January 2013 (has links)
This thesis deals with the possibility of using the finite elements method for the analysing of synchronous permanent magnets machines. The aim of this work is to discuss the possibility of the machine design more effectively with using the finite elements method and Maxwell software for the simulations. On the created parametric model, simulations were performed according to master thesis assignment. The aim of this work is to determine induced voltage, iron losses, machine inductances and make a permanent magnets demagnetization analysis. From simulations results the machine efficiency is calculated. The parametric model was used for the optimization of selected parameters. From results of optimization new dimensions of permanent magnets was obtained. Machine efficiency was increased by new permanent magnet material and optimized design.
45

Návrh a analýza synchronních strojů s permanentními magnety a soustředěným vinutím / Design and analysis of PMSM with concentrated winding

Macek, Pavel January 2015 (has links)
Permanent magnet synchronous machine (PMSM) are widely used in many industrial applications. This thesis starts with familiarization with the properties and structure of each type of synchronous machines with permanent magnets. Subsequently there are described properties and possible division of AC winding types. Afterward analytical designs of four machines with two different types of winding were realized. These designs were compared by means of simulations using the RMxprt program and their properties were subsequently verified by method of finite element using the Maxwell 2D program. Evaluation and comparison in terms of utility properties for all designs of machines were performed at the conclusion of this thesis.
46

Analýza vlivu mechanického momentu asynchronního stroje na sycení magnetického obvodu / Mechanical Torque Analysis of Induction Machine Based on Magnetic Circuit Saturation

Skalka, Miroslav January 2011 (has links)
e main goal of this thesis is mechanical torque analysis of induction machine based on magnetic circuit saturation, oversaturated areas classification and the possibility of oversaturated areas reduction of their influence on machine properties. Whole problem is solved by finite element method in ANSYS program. Work is divided into the description and creating of electromagnetic model, a method of the induction machine equivalent circuit parameters determination, the electromagnetic field calculation by finite element method, experimental measurement using LabVIEW program with measurement accessories (PCIe card National Instruments), data processing program in DIAdem, results analysis of calculations in terms of magnetic circuit saturation, the influence of magnetic circuit material based on electromagnetic field distribution and the magnetic flux density along the air gap including spectral analysis using MATLAB and the electromagnetic torque and its parasitic torque components calculation.
47

Einfluss der Bekeimung auf die Qualität von schmelztexturierten YBCO-Hochtemperatur-Supraleitern

Bierlich, Jörg 05 December 2008 (has links)
Die für technische Anwendungen attraktivsten Eigenschaften der Hochtemperatur-Supraleiter beruhen auf der Wechselwirkung der Materialien mit einem externen Magnetfeld. Für hochleistungsfähige Supraleiteranwendungen werden großvolumige Funktionselemente mit eindomänigem Magnetisierungsverhalten benötigt. Zur Vergrößerung der magnetischen Domäne schmelztexturierter YBa2Cu3O7-δ-Kompaktsupraleiter wurde anhand der Multi-Seeding-Technik, die Rekristallisation unter Verwendung mehrerer SmBa2Cu3O7-δ-Keimpräparate untersucht. Als Schlüsseltechnologie zur Herstellung anwendungsorientierter Supraleitererzeugnisse wurde zu Beginn der Arbeit die Keimkristallherstellung optimiert. Gemäß den Zielvorgaben stehen zukünftig quasi-einkristalline Keimkörper definierter Form und Orientierung in hoher Stückzahl zur Verfügung. Die Supraleiter betreffend ist es gelungen, für den wechselseitigen Abstand und die Ausrichtung der Keimpräparate ein Optimum zu finden sowie tolerierbare Winkel der Verschwenkung angrenzender Kristalle zu ermitteln. Es wurde festgestellt, dass das Auftreten isolierender Korngrenzeneinschlüsse mit den magnetischen Materialeigenschaften korreliert und vom Keimabstand und der Korngrenzenorientierung abhängig ist. Mit Einsatz von bis zu 16 Keimkristallen gelang es, eindomänige Supraleiterhalbzeuge mit Höchstmaßen von (79 x 39 x 20) mm3 und Remanenzflussdichten von bis zu 1,3 T zu erzeugen. Im Chargenprozess konnten abschließend Multi-Seeding-Funktionselemente mit anwendungskonformen geometrischen und magnetischen Materialeigenschaften zum Aufbau eines hochdynamischen Supraleitermotors reproduzierbar gefertigt werden. In Leistungstests wurde für die Dynamik des Motors mit 200.000 rpm/s ein Rekordwert erzielt – nun können die Motoren in der Anwendung erprobt werden.
48

The role of tree height and wood density for the water use, productivity and hydraulic architecture of tropical trees

Link, Roman Mathias 19 February 2020 (has links)
No description available.
49

電磁鋼板の局所領域磁気特性および加工劣化に関する研究 / デンジ コウハン ノ キョクショ リョウイキ ジキ トクセイ オヨビ カコウ レッカ ニカンスル ケンキュウ

千田 邦浩, Kunihiro Senda 03 March 2016 (has links)
電磁応用機器の特性向上に繋がる基礎的知見を得ることを目的とし,電磁鋼板および鉄心内部の局所的な磁気特性の分布に着目した研究を行った。方向性電磁鋼板については,鋼板内部の局所領域の磁気特性の測定手法を開発し,磁気特性の不均一分布の原因を解明した。無方向性電磁鋼板においては,打抜き,カシメ,応力といった鉄心製造に関わる因子の影響を評価し,鉄心での磁気特性劣化の機構を明らかにした。 / 博士(工学) / Doctor of Philosophy in Engineering / 同志社大学 / Doshisha University
50

Magnetic Characterization of the Nugget Microstructure at Resistance Spot Welding

Mathiszik, Christian, Zschetzsche, Edwin, Reinke, André, Koal, Johannes, Zschetzsche, Jörg, Füssel, Uwe 22 May 2024 (has links)
Conventional resistance spot welds are not visible from the outside. Therefore, it is not straightforward to evaluate the joint quality non-destructively. The pulse-echo method of manual ultrasonic is widely used for non-destructive testing. Another option is the passive magnetic flux density testing, which is being developed at Technische Universität Dresden, Germany. The spot weld is magnetized in the normal direction and the residual magnetic flux density is measured on top of the surface of the joint. This method is suitable for spot welds on typical car body steels. Previous investigations show that the magnetic properties of the materials influence the test result. In order to develop this new non-destructive testing method further, it is necessary to know the magnetic properties of the different microstructure regions of a spot weld. This article focuses on methods to measure and evaluate the magnetic properties of these regions, especially of the base material and the weld. Different measuring methods and approaches are presented and compared with each other. Based on the results, recommendations for future measurements for magnetic characterizations are given.

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