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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.
61

Prise en compte de la CEM dans une méthodologie de pré-dimensionnement par optimisation déterministe en électronique de puissance : application à un redresseur triphasé aéronautique / Taking into account EMC in a pre-design methodology using deterministic optimization for power electronics : application to a three-phase rectifier for aeronautics

Baraston, Arnaud 07 February 2019 (has links)
Ce travail s’inscrit dans l’optique de prédimensionnement par optimisation déterministe en électronique de puissance. Nous nous focalisons principalement sur la problématique de la Compatibilité ElectroMagnétique que nous désirons inclure dans la démarche. Pour cela, nous considérons l’exemple d’un redresseur triphasé comportant des filtres CEM à la fois du côté triphasé et du côté continu. Un couplage de mode commun a lieu entre les deux filtres, ils doivent donc être conçus simultanément. Des modéles de dimensionnement du convertisseur et de ses différents composants (passifs, interrupteurs, refroidisseur) ont été élaborés. Dans la procédure d’optimisation, l’ensemble des variables de cette modélisation globale du convertisseur (valeur des éléments fonctionnels, stratégie de commande MLI et fréquence de découpage) impacte les émissions CEM conduites. Ainsi, le modèle de calcul CEM est intégré dans le déroulement du processus, qui vise à minimiser la masse du convertisseur. Grâce à cela nous obtenons une approche globale où les filtres CEM sont dimensionnés en parallèle avec le convertisseur, et non une fois que la conception de ce dernier soit terminée, comme c’est classiquement le cas.La variation de la fréquence de découpage durant l’optimisation a constitué le problème majeur. Nous avons dû développer des stratégies concernant la surveillance des spectres CEM pour arriver à diminuer drastiquement les temps de calcul. Nous avons aussi développé une formulation de la contrainte CEM et une stratégie de lancement automatique d’optimisations déterministes avec paramétrage initial aléatoire qui a permis aux dimensionnements d’aboutir. Tout au long de la thèse, l’accent a été mis sur la généricité des modèles, qu’ils touchent à la CEM ou aux autres points du dimensionnement, en vue de leur adaptabilité à d’autres cas d’application. / This thesis deals with the sizing of power electronics using deterministic optimization. In this way, methods to integrate the ElectroMagnetic Compatibility constraints in such process were studied. The case of a three-phase rectifier with EMC filters on both AC and DC sides was considered. A common-mode path creates an interaction between the two filters, thus they have to be sized together. Models of the converter and its components were developed for their sizing by deterministic optimizations. In such conception problem, all the parameters used for describing the system configuration (functional elements values, PWM command strategy and the switching frequency) influence the conducted EMC emissions. Therefore, the modeling of the EMC constraints was integrated in the optimization procedure, which aims the overall weight reduction. Thanks to that, a global approach where EMC filters are sized along with the converter was achieved, whereas it is usually done after the converter conception.The main challenge was the variation of the switching frequency in optimization. Strategies were developed regarding the automatic surveillance of the EMC spectrums in order to drastically reduce their computation times. An innovative formulation of the EMC constraints enabled the optimizations to converge. An automatic procedure for launching multiple deterministic optimizations with random initial parameters allowed us to obtain good optimization results, regarding the constraints and the global weight of the system. In this work, genericity of the modelling approach was a main concern, regarding EMC and the different sizing models. Therefore, the adaptation of the developed methods to other applications should be convenient.
62

Investigation on EMI of Self-Ballasted Fluorescent Lamps

Chao, Chih-Feng 10 August 2011 (has links)
According to the regulation announced by Bureau of Standard, Metrology & Inspection (BSMI) of Ministry of Economic Affairs (MOEA), lamp fixtures must follow safety and electromagnetic compatibility (EMC) standards. However, the self-ballasted fluorescent lamps in the fixture should only be approved by the safety test but not regulated by EMC standard. Obviously, fixtures without light bulbs do not generate any electromagnetic noise. Electromagnetic interference (EMI) comes from the fluorescent light bulb embedded with an electronic ballast which included an inverter with high-frequency switching. A variety of tests demonstrate evidently that a fixture with different self-ballasted compact fluorescent lamps may possibly violate the EMC standard, revealing the absurdity of the regulation. In fact, self-ballasted fluorescent lamps use mostly self-excited electronic ballasts. The operating frequencies for this kind of electronic ballasts can not be precisely controlled due to the influence of many factors. They are not operated at a specified frequency but in a frequency range. This means that the generated EMI spectrum is hardly predicted, especially when a fixture is fitted by light bulbs from several manufacturers. This research inducts the worst cases from numerous measurements on a fixture with 1 piece to 8 pieces of light bulbs, and then attempts to design an EMI filter for all cases. As a result, a lamp fixture with the filter at the line input terminal can suppress the EMI. As long as the consumer buys the lamp fixture which are installed with the EMI filter together with any bulb in use, EMI noise can comply with standard limits.
63

EMC Internal Antennas for Mobile Communication Devices

Su, Chih-ming 24 May 2006 (has links)
In this dissertation, EMC antennas for mobile communication device applications are proposed. This kind of EMC antennas can overcome the problem that happens to the conventional antenna; in practical application, when electronic components are placed very close to the conventional antenna, large degradation of the antenna performance will occur. In the proposed EMC antennas, by adding a vertical antenna ground plane functioning as a shielding metal wall, EM coupling between the EMC antenna and nearby components can be reduced. Thus, it leads to no degradation or only negligible variations of the antenna performance. Also, the concept of EMC antennas can be applied to the monopole antenna. One of the examples suitable for the future thin (< 10 mm) mobile communication device is demonstrated. Further, the user¡¦s hand effects on EMC antenna performance are analyzed. Even when the mobile phone is hand-held at the bottom, large radiation efficiency drops are observed, especially for the GSM band.
64

NOVEL EMC CHIP ANTENNAS FOR WLAN APPLICATIONS

Chang, Chih-Hua 01 June 2006 (has links)
Novel chip antennas having an attractive EMC¡]Electromagnetic Compatibility¡^property for WLAN¡]Wireless Local Area Network¡^operations are demonstrated in this thesis. With the EMC property, the proposed antennas are suitable to be applied as internal antennas in mobile communication devices, such as the smart phones or PDA¡]Personal Digital Assistant¡^phones. With the antenna ground portion functioning as a new ground structure, the EM fringing fields in the surrounding region of the proposed antennas are greatly reduced to be negligible. When the possible RF shielding metal case or other electronic components are placed close to the proposed antennas, the antenna performances are almost unaffected. In other words, the isolation distance between the antenna and the nearby components will be no long required. This can lead to a compact integration of the proposed antennas with the nearby components in mobile communication devices. Details of the measured and simulated results of the proposed EMC chip antennas are presented and discussed.
65

A Study on Factorial Designs with Blocks Influence and Inspection Plan for Radiated Emission Testing of Information Technology Equipment

Wong, Kam-Fai 29 June 2001 (has links)
Draper and Guttman (1997) show that for basic 2^{k-p}designs, p >= 0, k-p replicates of blocks designs of size two are needed to estimate all the usual (estimable) effects. In Chapter 1, we provide an algebraic formal proof for the two-level blocks designs results and present results applicable to the general case; that is, for the case of s^{k} factorial (p=0) or s^{k-p}ractional factorial (p>0) designs in s^{b} blocks, where 0<b<k-p, at least (k-p)/(k-p-b) replicates are needed to clear up all possible effects. Through the theoretical development presented in this work, it can provide a clearer view on why those results would hold. We will also discuss the estimation equations given in Draper and Guttman (1997). In Chapter 2, we present a methodology for analyzing the variability of the radiated emission testings of electronic, elecommunication and information technology equipment based on a modified analysis of variance (ANOVA), with polynomial regression analysis. In our study, three electronic products; modem, monitor and notebook bought from the market are tested. Through the experiment, we show that the international standard fails to provide a methodology which gives control limits for EMC when the electronic products in question are produced. We feel that an improved EMC control procedure presented here can better meet the needs of radiated emission control.
66

Simulation and Measurement of the Normalized Site Transmission Loss of the Compact EMC Chamber

Chen, Li-Rung 22 June 2002 (has links)
Compact fully anechoic chambers may gradually replace open area test sites as the preferred type of testing facility for the measurement of radiated emissions. This dissertation theoretically and experimentally investigates the suitability of a compact fully anechoic chamber with ferrite tiles being partially lined on the floor ground as a free-space environment at frequency range below 300MHz. The results show that, for vertical polarization, the practical chamber will behave like a free-space test site. However, for the horizontal polarization, it seems have relatively significant effect on the NSTL performance and will not behave well like a free-space test site. Based on FDTD modeling approach, a numerical tool with the measuring tunable dipole antennas being considered is established to simulate the NSTL performance of the compact EMC chamber with different layout design of ferrite tiles. Furthermore, several designs of reduced coverage of the ferrite tiles in the compact chamber are proposed and discussed. In addition, this dissertation also investigates the correlation test of a 3m fully anechoic chamber ¡]FAC¡^ and a 10m semi-anechoic chamber ¡]SAC¡^ at frequency range from 80MHz to 1000MHz. Based on correction factor between two test sites, the EMI behaviors of the EUT in a 10m SAC could be predicted rapidly at frequency from 200MHz to 900MHz. Thus, a 3m FAC has been expected to provide a low cost as a pre-compliance test site, if the predicted EMI behaviors of the EUT are close to the practical measured results in a 10m SAC.
67

Charakterisierung der Modenverwirbelungskammer der TU Dresden und Untersuchung von Verfahren zur Bestimmung der unabhängigen Rührerstellungen

Pfennig, Stephan 08 June 2015 (has links) (PDF)
Die Elektromagnetische Verträglichkeit (EMV) betrachtet die Fähigkeit eines elektrischen Gerätes, in seiner elektromagnetischen Umgebung störungsfrei zu funktionieren, ohne diese dabei unzulässig zu stören. Zur Prüfung der Elektromagnetischen Verträglichkeit werden verschiedene Messumgebungen verwendet. Die Messung der strahlungsgebundenen Störfestigkeit und Störaussendung kann zum Beispiel in einer Modenverwirbelungskammer (MVK) erfolgen. Bei der Störfestigkeitsmessung wird der Prüfling einem externen Prüffeld ausgesetzt und untersucht, ob dieser die definierten Kriterien für einen störungsfreien Betrieb erfüllt. Für das Prüffeld muss vor der Messung nachgewiesen werden, dass die Anforderungen an dessen Homogenität eingehalten werden. Einen entscheidenden Einfluss auf die Homogenität des Prüffeldes hat der sogenannte Rührer. Bei einer MVK handelt es sich prinzipiell um einen Hohlraumresonator, in den ein mechanischer Rührer, d.h. ein elektrisch großer, drehbarer Streukörper integriert wird. Durch die Drehung des Rührers verändert sich die Feldverteilung in der MVK, was auch als Verwirbelung bezeichnet wird. Prinzipiell ergibt sich für jede Stellung des Rührers ein inhomogenes Feld mit lokalen Minima und Maxima. Ein Ziel bei der Verwendung von Modenverwirbelungskammern ist es, mit Hilfe geeigneter Verfahren Rührerstellungen zu finden, deren Feldverteilungen in Überlagerung ein möglichst homogenes Prüffeld erzeugen. Zum Lehrstuhl für Theoretische Elektrotechnik und Elektromagnetische Verträglichkeit der Technischen Universität Dresden gehört seit 2010 eine Modenverwirbelungskammer. Die Charakterisierung dieser MVK sowie eine weiterführende Untersuchung zur Wahl der Rührerstellungen bilden die Schwerpunkte der vorliegenden Arbeit. / In 2010 the Chair of Electromagnetic Theory and Compatibility of Technical University Dresden could extend its laboratories by a reverberation chamber with the dimensions 5.3 m, 3.7m and 3.0 m. Since then, a detailed characterisation of the chamber as well as further investigations have been the main emphasis of the authors research. The submitted doctoral thesis presents the obtained results. With the design, the fundamentals of operation and further characterisation of the reverberation chamber, given in Chapter 1 and 2, it aims to give an introduction and better understanding of reverberation chambers. On this basis, the authors research focused on methods for determining the independent stirrer positions in reverberations chambers. The results of the investigations are presented and summarised in chapter 3. One scope of Electromagnetic Compatibility are radiated immunity measurements. Besides the GTEM cell and the anechoic chamber the reverberation chamber gains in importance as an alternative measurement environment. A reverberation chamber is a shielded room with reflecting walls and one or more integrated mechanical stirrers. By rotating the stirrer the spatial boundary conditions for the electromagnetic field quantities are altered. The resulting change of the spatial field distribution depends on the location within the chamber and the geometry of the stirrer. Each stirrer position yields an inhomogeneous field distribution created by interfering waves. A general aim is to find a set of stirrer positions, whose superimposed field distributions create a more uniform test field. In practice, the given requirements for the homogeneity of the test field shall, with regards to an optimisation of measurement time, be realized with a minimum number of stirrer positions. In this context the term ’independent stirrer positions’ was established and describes stirrer positions, whose field distributions are linearly uncorrelated and therefore assumed to be practical for creating a more homogeneous test field using only a minimal number of stirrer positions. A general method for determining the number of independent stirrer positions in reverberation chambers is presented. The method uses a certain number of measurement positions in a defined test volume in order to characterize the spatial field distribution inside the chamber. Using the Pearson correlation coefficient the field distributions of the stirrer positions are tested for linear correlation and pairs of independent stirrer positions are determined. On this basis, cliques of pairwise independent stirrer positions are identified using appropriate algorithms. It is shown that the general method yields detailed information about the number and distribution of the independent stirrer positions and is therefore particularly suitable to evaluate other methods. Finally, the standard method according to IEC 61000-4-21 as well as selected alternative methods, that have been proposed in the past, are evaluated and compared based on the results of the general method.
68

A FULL SYSTEM CHARACTERIZATION OF THE MEASUREMENT UNCERTAINTY OF A CONDUCTED EMISSIONS MEASUREMENT SYSTEM

Menke, Robert A. 01 January 2005 (has links)
Electromagnetic compatibility (EMC) standards for an accredited test laboratory require that the measurement uncertainty of the measuring instruments be characterized. The CISPR 16-4 standard gives guidance to the magnitude of this uncertainty, but no method of characterization. This thesis describes a method to perform this characterization on a conducted emissions measurement system, taking advantage of full system analysis techniques to reduce the uncertainty to exceptionally low levels. In addition, a framework is introduced whereby uncertainty can decomposed into its constituent parts such that the laboratory operator can identify methods to improve the systems performance.
69

SPATIAL LOCATION OF ELECTROSTATIC DISCHARGE EVENTS WITHIN INFORMATION TECHNOLOGY EQUIPMENT

Oglesbee, Robert A. 01 January 2007 (has links)
In this thesis, a system to locate an electrostatic discharge (ESD) event within an electronic device has been developed. ESD can cause a device to fail legally required radiated emissions limits as well as disrupt intended operation. The system used a fast oscilloscope with four channels, each channel attached to a high frequency near-field antenna. These antennas were placed at known locations in three dimensional space to measure the fields radiated from the ESD event. A Time-Difference-of-Arrival technique was used to calculate the location of the ESD event. Quick determination of the ESD event location provides developers with a tool that saves them time and money by eliminating the time-consuming and tedious method of general ESD mitigation within a product.
70

Instrument för verifiering av kabelgenomföringar : ­Framtagande och provning av principmodell

Hedin, Tobias January 2018 (has links)
Elektromagnetiska störningar kan orsaka stora och allvarliga problem både i land och ombord på fartyg. Störningar som kommer in i kontrollerade utrymmen via kablage kan förhindras genom speciellt framtagna kabelgenomföringar. Dock gäller att dessa är installerade korrekt och syftet med detta arbete är att ta fram en principmodell för ett portabelt kontrollinstrument för kontroll av elektromagnetisk kompatibilitet (EMC).   Genom att ta delar ur flertalet internationella standarder inom EMC-området togs en principmodell för kontrollinstrumentet fram. Genom simulering kunde delar av principen fastställas och sedan utfördes praktiska prover där testuppsättningen hade sitt ursprung i en vedertagen och beprövad uppsättning.   Proverna visade på att principmodellen fungerar. Dock uppnådde inte modellens mätenhet samma mätnoggranhet som referensinstrumentet och dämpningar i de framtagna kretsarna skiljde sig från de framräknade värdena.

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