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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.
1

Integrated Design of EMI Filter and Power-Factor-Correction Circuit

Tsai, Huai-Chin 04 July 2000 (has links)
In this thesis, an alternative solution for designing power line conductive electromagnetic interference (EMI) filter by using the consecutive orthogonal array method is proposed. The circuit parameters of EMI filters to be determined are assigned as the control variables in the orthogonal arrays, and the average effects corresponding to each control variable are calculated from the measured results. In accordance with the inferential rules, the average effects are used as the observational indices to adjust the levels of the control variables of the subsequent orthogonal array. Through manipulating consecutive orthogonal arrays step by step, the applicable ranges of circuit parameters are approached with desired output performances. Finally, the component values of EMI filters with minimum size can be found. The design procedure and the inferential rules are described by illustrative examples for a single-stage high-power-factor converter.
2

Metal-reduced graphene oxide for supercapacitors and alternating current line-filters

Wu, Zhenkun 21 September 2015 (has links)
We design a facile approach to investigate the role benzene derivatives play in the capacitance enhancement of graphene-based supercapacitors. The main reason is attributed to the pseudocapacitance of the aromatic molecules rather than the former one. Meanwhile, we find that the para and ortho substituted benzene derivatives contribute much more than the meta substituted ones. In addition, we fabricate an all-solid-state flexible MSC based on metal-reduced GO. The as-fabricated MSC shows high areal capacitance and excellent reliability, which makes it a promising energy storage candidate for wearable electronics. Based on the work of MSC, we achieve a flexible ac line-filter that is not only competitive against commercial product but also suitable for mass production. Meanwhile, we produce a three-dimensional graphene/polydimethylsiloxane composite that gives a thermal resistance as small as 14 mm2K/W, which is comparable to commercial products. What’s more, a convenient transient program that saves much time is developed to measure the thermal resistance.
3

All-optical Microwave Signal Processing

Han, Yichen 22 September 2011 (has links)
Microwave signal processing in the optical domain is investigated in this thesis. Two signal processors including an all-optical fractional Hilbert transformer and an all-optical microwave differentiator are investigated and experimentally demonstrated. Specifically, the photonic-assisted fractional Hilbert transformer with tunable fractional order is implemented based on a temporal pulse shaping system incorporating a phase modulator. By applying a step function to the phase modulator to introduce a phase jump, a real-time fractional Hilbert transformer with a tunable fractional order is achieved. The microwave bandpass differentiator is implemented based on a finite impulse response (FIR) photonic microwave delay-line filter with nonuniformly-spaced taps. A microwave bandpass differentiator based on a six-tap nonuniformly-spaced photonic microwave delay-line filter with all- positive coefficients is designed, simulated, and experimentally demonstrated. The reconfigurability of the microwave bandpass differentiator is experimentally investigated. The employment of the differentiator to perform differentiation of a bandpass microwave signal is also experimentally demonstrated.
4

All-optical Microwave Signal Processing

Han, Yichen 22 September 2011 (has links)
Microwave signal processing in the optical domain is investigated in this thesis. Two signal processors including an all-optical fractional Hilbert transformer and an all-optical microwave differentiator are investigated and experimentally demonstrated. Specifically, the photonic-assisted fractional Hilbert transformer with tunable fractional order is implemented based on a temporal pulse shaping system incorporating a phase modulator. By applying a step function to the phase modulator to introduce a phase jump, a real-time fractional Hilbert transformer with a tunable fractional order is achieved. The microwave bandpass differentiator is implemented based on a finite impulse response (FIR) photonic microwave delay-line filter with nonuniformly-spaced taps. A microwave bandpass differentiator based on a six-tap nonuniformly-spaced photonic microwave delay-line filter with all- positive coefficients is designed, simulated, and experimentally demonstrated. The reconfigurability of the microwave bandpass differentiator is experimentally investigated. The employment of the differentiator to perform differentiation of a bandpass microwave signal is also experimentally demonstrated.
5

All-optical Microwave Signal Processing

Han, Yichen 22 September 2011 (has links)
Microwave signal processing in the optical domain is investigated in this thesis. Two signal processors including an all-optical fractional Hilbert transformer and an all-optical microwave differentiator are investigated and experimentally demonstrated. Specifically, the photonic-assisted fractional Hilbert transformer with tunable fractional order is implemented based on a temporal pulse shaping system incorporating a phase modulator. By applying a step function to the phase modulator to introduce a phase jump, a real-time fractional Hilbert transformer with a tunable fractional order is achieved. The microwave bandpass differentiator is implemented based on a finite impulse response (FIR) photonic microwave delay-line filter with nonuniformly-spaced taps. A microwave bandpass differentiator based on a six-tap nonuniformly-spaced photonic microwave delay-line filter with all- positive coefficients is designed, simulated, and experimentally demonstrated. The reconfigurability of the microwave bandpass differentiator is experimentally investigated. The employment of the differentiator to perform differentiation of a bandpass microwave signal is also experimentally demonstrated.
6

All-optical Microwave Signal Processing

Han, Yichen January 2011 (has links)
Microwave signal processing in the optical domain is investigated in this thesis. Two signal processors including an all-optical fractional Hilbert transformer and an all-optical microwave differentiator are investigated and experimentally demonstrated. Specifically, the photonic-assisted fractional Hilbert transformer with tunable fractional order is implemented based on a temporal pulse shaping system incorporating a phase modulator. By applying a step function to the phase modulator to introduce a phase jump, a real-time fractional Hilbert transformer with a tunable fractional order is achieved. The microwave bandpass differentiator is implemented based on a finite impulse response (FIR) photonic microwave delay-line filter with nonuniformly-spaced taps. A microwave bandpass differentiator based on a six-tap nonuniformly-spaced photonic microwave delay-line filter with all- positive coefficients is designed, simulated, and experimentally demonstrated. The reconfigurability of the microwave bandpass differentiator is experimentally investigated. The employment of the differentiator to perform differentiation of a bandpass microwave signal is also experimentally demonstrated.
7

Modeling and Characterization of Power Electronic Converters with an Integrated Transmission-Line Filter

Baisden, Andrew Carson 24 July 2006 (has links)
In this work, a modeling approach is delineated and described in detail; predominantly done in the time domain from low frequency, DC, to high frequencies, 100 MHz. Commercially available computer aided design tools will be used to determine the propagation path in a given structure. Next, an integrated transmission-line filter — fabricated using planar processing technologies — is modeled to accurately predict the EMI characteristics of the system. A method was derived to model the filter's performance in the time-domain while accurately depicting the highly frequency dependant transmission-line properties. A system model of a power factor correction (PFC) boost converter was completed by using active device models for diodes, MOSFETs, and the gate driver. In addition, equivalent circuits were used to characterize high frequency impedances of the passive components. A PFC boost converter was built and used to validate the model. The PFC operated at a peak output power of 1 kW, switching at 400 kHz, with a universal input ranging from 90-270 VRMS with unity power factor. The time-domain and EMI frequency spectrum waveforms are experimentally measured and agree very well with the simulated values; within 5 dB for EMI. The transmission-line filter was also manufactured for model verification, and it is tested for the first time with an operating converter: a PFC at 50 W output and 50 VDC input. The small signal characteristics match the model very well. In addition, impedance interactions between the filter, the converter, and the EMI measurement set-up are discussed, evaluated, measured, and improved to minimize undesired resonances and increase low-frequency EMI attenuation. Experimentally measured attenuation provided by the filter in the range from 100 kHz to 100 MHz was 20-50 dBμV. The simulation also shows a similar attenuation, with the exception of one key resonance not seen in the simulation. / Master of Science
8

Untersuchung und Herstellung faseroptischer Delay-Line-Filter zur Dispersionskompensation in optischen Übertragungssystemen / Investigations on fiber optic delay line filters for dispersion compensation

Duthel, Thomas 14 November 2005 (has links) (PDF)
Die chromatische Dispersion ist in optischen Übertragungssystemen mit Datenraten von 10 Gbit/s und darüber einer der Faktoren, der die Länge der Übertragungsstrecke limitiert. Der Hauptteil der chromatischen Dispersion wird in solchen Übertragungssystemen in der Regel durch Dispersionskompensationsfasern ausgeglichen. Aufgrund von z.B. Umwelteinflüssen kann allerdings auch eine sich zeitlich ändernde Dispersion auftreten. Zur Eliminierung dieser Restdispersion wurden unterschiedliche Ansätze wie abstimmbare Faser-Bragg-Gitter, Virtually-Imaged-Phased-Arrays und Delay-Line-Filter publiziert. Delay-Line-Filter, deren periodisches Übertragungsverhalten durch die Filterkoeffizienten bestimmt wird, wurden bereits als Ring-Resonatoren und kaskadierte Mach-Zehnder-Interferometer in integriert-optischer Technologie hergestellt. Integriert-optische Komponenten verursachen aufgrund der Ankopplung an die Fasern des Übertragungssystems hohe Einfügeverluste. Darüber hinaus treten hohe Wellenleiterverluste, polarisationsabhängige Verluste und Polarisationsmodendispersion auf. Daher wird in dieser Arbeit die Realisierung faseroptischer Delay-Line-Filter, die auf faseroptischen Schmelzkopplern und faseroptischen Gewichtungselementen basieren, untersucht. Aufgrund der geometrischen Längen der faseroptischen Schmelzkoppler und der Größe der Gewichtungselemente können solche Filter allerdings nur mit einer geringen Filterordnung und mit einer geringen Anzahl von Gewichtungselementen hergestellt werden. Um mit Filtern niedriger Ordnung eine möglichst effektive Kompensation der Restdispersion zu erzielen, ist zunächst eine sorgfältige Untersuchung der Filtereigenschaften und des Filterentwurfs erforderlich. Durch systematische Untersuchung des Verhaltens der Filterdispersion in Abhängigkeit der Filterkoeffizienten wurden in dieser Arbeit hierzu erstmalig einfache Entwurfsregeln aufgestellt, die für Filter beliebiger Filterordnung zu annähernd konstantem Dispersionsverlauf führen. Auf dieser Grundlage konnte ein faseroptisches Delay-Line-Filter realisiert werden, das auf zwei in Reihe geschalteten faseroptischen 3x3 Schmelzkopplern basiert. Die Dispersion dieses Filters ist in einem Bereich von 50 GHz um die Mitte einer Filterperiode herum annähernd konstant und kann in einem Bereich von +/-50 ps/nm durch ein einzelnes thermisches Gewichtungselement abgestimmt werden. Aufgrund der faseroptischen Realisierung kann die Komponente problemlos in optische Übertragungsstrecken integriert werden und verursacht dabei Einfügeverluste von lediglich 3 dB. In Übertragungsexperimenten bei Datenraten von 42,5 Gbit/s konnte gezeigt werden, dass das Filter in der Lage ist die Dispersionstoleranz des Systems annähernd zu verdoppeln. Dies gilt sowohl für die Kompensation eines einzelnen Kanals als auch für die simultane Kompensation mehrerer benachbarter Übertragungskanäle mit je 42,5 Gbit/s. / Chromatic dispersion is a limiting factor in fast optical networks with channel bit rates of 10 Gbit/s or higher. The main part of the dispersion is usually compensated by spans of dispersion compensating fiber that have a fixed dispersion value. But the residual dispersion caused by environmental changes or rerouting has to be compensated adaptively. To overcome the effects of residual dispersion several approaches like tunable fiber Bragg gratings, virtually imaged phased arrays and delay line filters can be found in literature. The use of delay line filters like cascaded ring-resonators, multi-cavity etalons and cascaded Mach-Zehnder interferometers, whose periodic transfer behavior is determined by their coefficients, have already been developed in planar-optics. These components cause insertion loss due to the coupling to the fibers. Furthermore they suffer from high waveguide loss, non-negligible polarization dependent loss and polarization mode dispersion. In this thesis the realization of tunable delay line filters based on fiberoptic couplers and fiberoptic weighting elements is investigated. Due to the size of these components the filters can be realized with a limited order and a limited number of weighting elements, only. To fulfill these requirements a careful investigation of the filter design is necessary. By systematically investigating the dispersion of the filter depending on the filter coefficients simple design rules for non-recursive delay line filters with approximately constant dispersion are figured out. That enables the realization of a fiberoptic delay line filter, based on two 3x3 couplers concatenated in series. The dispersion of this filter is constant in a bandwidth of about 50 GHz around the center of a period and can be tuned in a range of +/-50 ps/nm by changing one single weighting element. Due to its nature this device causes low loss and can be easily integrated in an optical transmission system. In experiments it was demonstrated that by adding this filter to a 42.5 Gb/s transmission system the +/- 55 ps/nm dispersion tolerance of the optical receiver can almost be doubled - either in a single channel as well as in a multi channel configuration with five adjacent 42.5 Gb/s channels.
9

Untersuchung und Herstellung faseroptischer Delay-Line-Filter zur Dispersionskompensation in optischen Übertragungssystemen

Duthel, Thomas 02 September 2005 (has links)
Die chromatische Dispersion ist in optischen Übertragungssystemen mit Datenraten von 10 Gbit/s und darüber einer der Faktoren, der die Länge der Übertragungsstrecke limitiert. Der Hauptteil der chromatischen Dispersion wird in solchen Übertragungssystemen in der Regel durch Dispersionskompensationsfasern ausgeglichen. Aufgrund von z.B. Umwelteinflüssen kann allerdings auch eine sich zeitlich ändernde Dispersion auftreten. Zur Eliminierung dieser Restdispersion wurden unterschiedliche Ansätze wie abstimmbare Faser-Bragg-Gitter, Virtually-Imaged-Phased-Arrays und Delay-Line-Filter publiziert. Delay-Line-Filter, deren periodisches Übertragungsverhalten durch die Filterkoeffizienten bestimmt wird, wurden bereits als Ring-Resonatoren und kaskadierte Mach-Zehnder-Interferometer in integriert-optischer Technologie hergestellt. Integriert-optische Komponenten verursachen aufgrund der Ankopplung an die Fasern des Übertragungssystems hohe Einfügeverluste. Darüber hinaus treten hohe Wellenleiterverluste, polarisationsabhängige Verluste und Polarisationsmodendispersion auf. Daher wird in dieser Arbeit die Realisierung faseroptischer Delay-Line-Filter, die auf faseroptischen Schmelzkopplern und faseroptischen Gewichtungselementen basieren, untersucht. Aufgrund der geometrischen Längen der faseroptischen Schmelzkoppler und der Größe der Gewichtungselemente können solche Filter allerdings nur mit einer geringen Filterordnung und mit einer geringen Anzahl von Gewichtungselementen hergestellt werden. Um mit Filtern niedriger Ordnung eine möglichst effektive Kompensation der Restdispersion zu erzielen, ist zunächst eine sorgfältige Untersuchung der Filtereigenschaften und des Filterentwurfs erforderlich. Durch systematische Untersuchung des Verhaltens der Filterdispersion in Abhängigkeit der Filterkoeffizienten wurden in dieser Arbeit hierzu erstmalig einfache Entwurfsregeln aufgestellt, die für Filter beliebiger Filterordnung zu annähernd konstantem Dispersionsverlauf führen. Auf dieser Grundlage konnte ein faseroptisches Delay-Line-Filter realisiert werden, das auf zwei in Reihe geschalteten faseroptischen 3x3 Schmelzkopplern basiert. Die Dispersion dieses Filters ist in einem Bereich von 50 GHz um die Mitte einer Filterperiode herum annähernd konstant und kann in einem Bereich von +/-50 ps/nm durch ein einzelnes thermisches Gewichtungselement abgestimmt werden. Aufgrund der faseroptischen Realisierung kann die Komponente problemlos in optische Übertragungsstrecken integriert werden und verursacht dabei Einfügeverluste von lediglich 3 dB. In Übertragungsexperimenten bei Datenraten von 42,5 Gbit/s konnte gezeigt werden, dass das Filter in der Lage ist die Dispersionstoleranz des Systems annähernd zu verdoppeln. Dies gilt sowohl für die Kompensation eines einzelnen Kanals als auch für die simultane Kompensation mehrerer benachbarter Übertragungskanäle mit je 42,5 Gbit/s. / Chromatic dispersion is a limiting factor in fast optical networks with channel bit rates of 10 Gbit/s or higher. The main part of the dispersion is usually compensated by spans of dispersion compensating fiber that have a fixed dispersion value. But the residual dispersion caused by environmental changes or rerouting has to be compensated adaptively. To overcome the effects of residual dispersion several approaches like tunable fiber Bragg gratings, virtually imaged phased arrays and delay line filters can be found in literature. The use of delay line filters like cascaded ring-resonators, multi-cavity etalons and cascaded Mach-Zehnder interferometers, whose periodic transfer behavior is determined by their coefficients, have already been developed in planar-optics. These components cause insertion loss due to the coupling to the fibers. Furthermore they suffer from high waveguide loss, non-negligible polarization dependent loss and polarization mode dispersion. In this thesis the realization of tunable delay line filters based on fiberoptic couplers and fiberoptic weighting elements is investigated. Due to the size of these components the filters can be realized with a limited order and a limited number of weighting elements, only. To fulfill these requirements a careful investigation of the filter design is necessary. By systematically investigating the dispersion of the filter depending on the filter coefficients simple design rules for non-recursive delay line filters with approximately constant dispersion are figured out. That enables the realization of a fiberoptic delay line filter, based on two 3x3 couplers concatenated in series. The dispersion of this filter is constant in a bandwidth of about 50 GHz around the center of a period and can be tuned in a range of +/-50 ps/nm by changing one single weighting element. Due to its nature this device causes low loss and can be easily integrated in an optical transmission system. In experiments it was demonstrated that by adding this filter to a 42.5 Gb/s transmission system the +/- 55 ps/nm dispersion tolerance of the optical receiver can almost be doubled - either in a single channel as well as in a multi channel configuration with five adjacent 42.5 Gb/s channels.
10

Caracterización multimodal de filtros de red y equipos electrónicos

Pérez Jiménez, Antonio 18 July 2008 (has links)
Un dels problemes més importants en la Compatibilitat Electromagnètica és el control de les interferències emeses i/o rebudes per un equip electrònic a través dels seus terminals d'alimentació monofàsica. Aquestes interferències es classifiquen en mode comú i mode diferencial. La manera més usual de mitigar-les és mitjançant la utilització de filtres de xarxa. Els mètodes actuals de disseny de filtres de xarxa tracten la mitigació d'aquest tipus d'interferències per separat: no tenen en compte que ambdós tipus de senyals (mode comú i diferencial) interaccionen entre sí i es transfereixen energia en qualsevol tipus d'asimetria originada pels equips electrònics o pels mateixos filtres. Aquest fet produeix freqüentment situacions inesperades: inefectivitat dels filtres de xarxa, aparició d'interferències en mode comú o diferencial inexplicables per la topologia dels circuits, selectivitat en freqüència del filtratge de les interferències, processos de radiació, etc. Aquest tipus de situacions poden ser analitzades i corregides a partir d'un anàlisi multimodal, que tingui en compte simultàniament el mode comú i el diferencial, i la seva interacció. El treball exposat aquí pretén:- Desenvolupar sistemes de mesura multimodal per a equips electrònics i filtres de xarxa. Aquests sistemes han de tenir en compte tant el mode comú, com el diferencial, com la seva interacció, i han de millorar les prestacions dels sistemes de mesura normatius actuals.- Trobar models equivalents des d'un punt de vista multimodal (tenint en compte simultàniament el mode comú, el diferencial i la seva interacció) tant d'equips electrònics com de filtres de xarxa.- Desenvolupar una metodologia de predicció de les interferències conduïdes que l'equip electrònic subministra a la xarxa elèctrica a través del filtre de xarxa al qual es troba connectat a partir dels models multimodals equivalents proposats per a ambdós dispositius.PARAULES CLAU: Compatibilitat electromagnètica, filtre de xarxa, equip electrònic, circuit equivalent, emissió conduïda, mode comú, mode diferencial, impedància d'entrada, paràmetres S. / Uno de los problemas más importantes en Compatibilidad Electromagnética es el control de las interferencias emitidas y/o recibidas por un equipo electrónico a través de sus terminales de alimentación monofásica. Estas interferencias se clasifican en modo común y modo diferencial. La manera más usual de mitigarlas es mediante el empleo de filtros de red. Los métodos actuales de diseño de filtros de red abordan la mitigación de este tipo de interferencias por separado: no tienen en cuenta que ambos tipos de señales (modo común y diferencial) interaccionan entre sí y se transfieren energía en cualquier tipo de asimetría originada por los equipos electrónicos o por los mismos filtros. Este hecho produce frecuentemente situaciones inesperadas: inefectividad de los filtros de red, aparición de interferencias en modo común o diferencial inexplicables por la topología de los circuitos, selectividad en frecuencia del filtrado de las interferencias, procesos de radiación, etc. Este tipo de situaciones pueden ser analizadas y corregidas a partir de un análisis multimodal, que tenga en cuenta simultáneamente el modo común y el diferencial, y su interacción. El trabajo aquí expuesto pretende:- Desarrollar sistemas de medida multimodal para equipos electrónicos y filtros de red. Dichos sistemas deben tener en cuenta tanto el modo común, como el diferencial, como su interacción, y deben mejorar las prestaciones de los sistemas de medida normativos actuales.- Hallar modelos equivalentes desde un punto de vista multimodal (teniendo en cuenta simultáneamente el modo común, el diferencial y su interacción) tanto de equipos electrónicos como de filtros de red.- Desarrollar una metodología de predicción de las interferencias conducidas que el equipo electrónico suministra a la red eléctrica a través del filtro de red al cual está conectado a partir de los modelos multimodales equivalentes propuestos para ambos dispositivos.PALABRAS CLAVE: Compatibilidad electromagnética, filtro de red, equipo electrónico, circuito equivalente, emisión conducida, modo común, modo diferencial, impedancia de entrada, parámetros S. / One of the most important problems in EMC is the control of the common and differential mode interferences emitted or received by an electronic device through its single phase power-line cable. These interferences are mitigated using power-line filters. The present power-line filter methodologies treat separately the mitigation of this kind of interferences: they do not take into account that both modes interact and exchange energy at any kind of asymmetry originated by the devices connected to the power-line, or by the power-line filters themselves. This fact leads to unexpected situations: power-line filter infectivity, appearance of common and differential mode interferences not accountable by the circuit topology, frequency selectivity of the interferences, radiation processes, etc. This kind of situations can be analyzed and corrected using multimodal analysis, which takes into account at the same time the common mode, the differential mode and their interaction. This project aims to:- Develop accurate multimodal measurement systems for both electronic devices and power-line network filters. They have to consider the common and differential modes, and their interaction, and have to improve the features of present normative measurement systems. - Derive equivalent models from a multimodal point of view (taking into account simultaneously the common mode, the differential mode and their interaction) for both electronic devices and power-line filters.- Develop a methodology for predicting the level of conducted emissions that an electronic device supplies to the power-line network through the power-line filter to which it is connected, using the equivalent multimodal models proposed for both devices.KEYWORDS: Electromagnetic compatibility, power-line filter, electronic device, equivalent circuit, conducted emissions, common mode, differential mode, input impedance, S parameters.

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