Dissertations / Theses on the topic 'High static power dissipation'
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Yu, Henry Hon-Kit. "Computer aided design of static reactive compensation for high voltage power systems." Thesis, University of Sunderland, 1992. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.293552.
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This thesis describes the development of a detailed set of step-by-step SVC system design procedures which allow manufacturers and operators to plan and develop optimum SVC systems for a given a.c. power transmission system. The validity of a typical svc system designed using the suggested procedures is investigated. The internationally recognised software package EMTP has been used as the primary Research tool, and principal features of this software, including those observed in the Research study also forms part of the discussion in the thesis. Previous conventional approaches to SVC simUlation have been restricted to simplified system models, and have only provided partial solutions to the design problem. In contrast, a detailed representation of three phase SVC systems using a time-domain approach is used in this research study in order to formulate a comprehensive design methodology. The SVC considered is for high voltage transmission applications, and is the TSC-TCR-FC type. A new optimisation program termed "OPTI-SVC" has also been developed to assist the SVC system design process. The system compensation limits must first be derived, and then for given equipment costs and system harmonic constraints, the program evaluates the optimum arrangement of the SVC primary system. Although certain simplifying assumptions are made and only those factors that can be taken into account analytically are considered, the program uses a worst case design philosophy in order to ensure acceptable performanceIn particular, Cost of the the program can minimise either the total svc system or the total harmonic voltage produced in the transmission system. In order to derive optimum control system settings, in particular for the SVC regulator, a structured trial and error approach has been developed. wi th the aid of the Astrom relay tuning technique, a good first estimation on optimum regulator settings for a given a.c. system condition can be obtained. The results are then systematically trimmed until a satisfactory system response is achieved. A three phase SVC system has been designed using the suggested approaches and applied to a generator fed transmission system. Realistic system data has been supplied by NEI Reyrolle Technology Limited. Simulated performance tests carried out demonstrate the correct functioning of the svc system against general accepted criteria, and hence the validity of the design procedure is established. As a primary research tool, the software EMTP has been proved to be very versatile although not user-friendly. Significant observations regarding the use of EMTP that are necessary to assist general users of the software package, are also revealed in the research study.
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RELE, SIDDHARTH N. "COMPILER OPTIMIZATIONS FOR POWER ON HIGH PERFORMANCE PROCESSORS." University of Cincinnati / OhioLINK, 2001. http://rave.ohiolink.edu/etdc/view?acc_num=ucin982010436.
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Etminan, S. "Simulation of high-speed static reactive compensation for suppression of power system disturbances." Thesis, University of Sunderland, 1990. http://ethos.bl.uk/OrderDetails.do?uin=uk.bl.ethos.253748.
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Mauck, Lisa D. "The role of rate dependence and dissipation in the constitutive behavior of ferroelectric ceramics for high power applications." Diss., Georgia Institute of Technology, 2002. http://hdl.handle.net/1853/15864.
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Qi, Yangjie. "FPGA Based High Throughput Low Power Multi-core Neuromorphic Processor." University of Dayton / OhioLINK, 2015. http://rave.ohiolink.edu/etdc/view?acc_num=dayton1449526140.
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Cebrián, González Juan Manuel. "Diseño de Mecanismos de Grano Fino para la Gestión Eficiente de Consumo y Temperatura en Procesadores Multinúcleo." Doctoral thesis, Universidad de Murcia, 2011. http://hdl.handle.net/10803/38362.
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En la última década los ingenieros informáticos se han enfrentado a profundos cambios en el modo en que se diseñan y fabrican los microprocesadores. Los nuevos procesadores no solo deben ser más rápidos que los anteriores, también deben ser factibles en términos de energía y disipación térmica, sobre todo en dispositivos que trabajan con baterías. Los problemas relacionados con consumo y temperatura son muy comunes en estos procesadores.
En esta Tesis analizamos el rendimiento, consumo energético y precisión de diferentes mecanismos de reducción de consumo y descubrimos que no son suficientemente buenos para adaptarse a un límite de consumo con una penalización de rendimiento razonable. Para solucionar este problema proponemos diversas técnicas a nivel de microarquitectura que combinan de manera dinámica varios mecanismos de reducción de consumo para obtener una aproximación al límite de consumo mucho más precisa con una penalización de rendimiento mínima.In the last decade computer engineers have faced changes in the way microprocessors are designed. New microprocessors do not only need to be faster than the previous generation, but also be feasible in terms of energy consumption and thermal dissipation, especially in battery operated devices. In this Thesis we worked in the design, implementation and testing of microarchitecture techniques for accurately adapting the processor performance to power constraints in the single core scenario, multi-core scenario and 3D die-stacked core scenario. We first designed “Power-Tokens”,to approximate the power being consumed by the processor in real time. Later we proposed different mechanisms based on pipeline throttling, confidence estimation, instruction criticality information, to adapt the processor to a predefined power budget . We also propose some layout optimizations for 3D die-stacked vertical designs.
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Malan, Frederich T. "Reduction of the antenna coupling in a bi-static, FM-CW radar system." Thesis, Stellenbosch : Stellenbosch University, 2011. http://hdl.handle.net/10019.1/18029.
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Thesis (MScEng)--Stellenbosch University, 2011.ENGLISH ABSTRACT: A well-known problem with FM-CW radar systems is the leakage of transmitter power into the receiver which leads to the making of close-in targets, and can severely limit the system dynamic range performance. This thesis considers two solutions to this radar system problem for a low frequency radar operating in the VHF band. The first method to suppress coupling is using separate transmit and receive antennas designed in such a way as to reduce coupling between them. The second is to design a negative feedback loop as part of the radar receiver where the feedback loop adaptively reduces the amount of transmitter leakage through to the receiver. This project details the realisation of these two solutions. A number of antenna designs are modelled in software and simulated to determine their characteristics of which the transmit-to-receive coupling is the key parameter. As no low coupling configuration could be found a simple configuration is chosen and practical measurements are taken. These antennas are then used in the radar system that is to be built. An FM-CW radar system is designed and simulated using software with a negative feedback loop being designed and implemented into the radar simulation. A practical radar system is then made inclusive of the feedback loop. Measurements are then taken to determine the efficacy of the feedback loop.
AFRIKAANSE OPSOMMING: ʼn Bekende probleem met FM-CW radar stelsels is die lekkasie van versender krag tot in die ontvanger wat lei tot die maak van nabye teikens en kan die stelsel se dinamiese sendbereik steng beperk. Hierdie tesis oorweeg twee oplossings tot hierdie probleem vir ʼn lae frekwensie radar wat in die VHF band werk. Die eerste metode wat na gekyk word om die koppeling te onderdruk is om die twee antennas van die radar stelsel so te ontwerp sodat die hoeveelheid koppeling tussen hulle verminder is. Die tweede is om ʼn negatiewe terugvoerlus as deel van die ontvanger te ontwerp. Hierdie terugvoerlus sal die versender lekkasie sein aanpassend in die ontvanger verminder. In hierdie projek word die realisering van bogenoemde oplossings uiteengeset. ʼn Paar verskillende antenna ontwerpe word gemodelleer in sagteware en word gesimuleer om hul karakteristieke te bepaal. Die belangrikste van hierdie faktore is die versender na ontvanger koppeling. Sienend dat geen ontwerp met ʼn lae genoeg koppeling gevind kon word nie, is ʼn eenvoudige ontwerp gekies en praktiese metings daarvan geneem. Hierdie antennas word dan gebruik in die radar stelsel wat gebou sal word. ʼn FM-CW radar stelsel word ontwerp en gesimuleer in sagteware. Die negatiewe terugvoerlus word ook ontwerp en geïmplementeer in die radar simulasie. ʼn Praktiese radar stelsel word dan gemaak insluitend die terugvoerlus. Metings word dan geneem om die effektiwiteit daarvan te bepaal.
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Hadjikypris, Melios. "Supervisory control scheme for FACTS and HVDC based damping of inter-area power oscillations in hybrid AC-DC power systems." Thesis, University of Manchester, 2016. https://www.research.manchester.ac.uk/portal/en/theses/supervisory-control-scheme-for-facts-and-hvdc-based-damping-of-interarea-power-oscillations-in-hybrid-acdc-power-systems(cc03b44a-97f9-44ec-839f-5dcbcf2801f1).html.
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Modern interconnected power systems are becoming highly complex and sophisticated, while increasing energy penetrations through congested inter-tie lines causing the operating point approaching stability margins. This as a result, exposes the overall system to potential low frequency power oscillation phenomena following disturbances. This in turn can lead to cascading events and blackouts. Recent approaches to counteract this phenomenon are based on utilization of wide area monitoring systems (WAMS) and power electronics based devices, such as flexible AC transmission systems (FACTS) and HVDC links for advanced power oscillation damping provision. The rise of hybrid AC-DC power systems is therefore sought as a viable solution in overcoming this challenge and securing wide-area stability. If multiple FACTS devices and HVDC links are integrated in a scheme with no supervising control actions considered amongst them, the overall system response might not be optimal. Each device might attempt to individually damp power oscillations ignoring the control status of the rest. This introduces an increasing chance of destabilizing interactions taking place between them, leading to under-utilized performance, increased costs and system wide-area stability deterioration. This research investigates the development of a novel supervisory control scheme that optimally coordinates a parallel operation of multiple FACTS devices and an HVDC link distributed across a power system. The control system is based on Linear Quadratic Gaussian (LQG) modern optimal control theory. The proposed new control scheme provides coordinating control signals to WAMS based FACTS devices and HVDC link, to optimally and coherently counteract inter-area modes of low frequency power oscillations inherent in the system. The thesis makes a thorough review of the existing and well-established improved stability practises a power system benefits from through the implementation of a single FACTS device or HVDC link, and compares the case –and hence raises the issue–when all active components are integrated simultaneously and uncoordinatedly. System identification approaches are also in the core of this research, serving as means of reaching a linear state space model representative of the non-linear power system, which is a pre-requisite for LQG control design methodology.
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Escamez, Guillaume. "AC losses in superconductors : a multi-scale approach for the design of high current cables." Thesis, Université Grenoble Alpes (ComUE), 2016. http://www.theses.fr/2016GREAT087/document.
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Le travail de cette thèse porte sur l'étude des pertes AC dans les supraconducteurs pour des applications tels que les câbles ou les aimants. Les modélisations numériques rapportées sont de type éléments-finis et méthode intégrale. Toutes ces méthodes visent à résoudre à calculer les distributions de densité de courant et de champ magnétique en prenant en compte différents loi de comportement pour le supraconducteur. Deux conducteurs sont introduits dans ce mémoire. Tout d'abord, les supraconducteurs à haute température critiques sont étudiées avec l'introduction d'une nouvelle forme de conducteur (fils cylindriques) et sont envisagés pour des câbles fort courant de 3~kA. Dans un second temps, des simulations numériques 3-D sont réalisés sur un conducteur MgB2. Le chapitre suivant traite des contraintes de calculs des pertes dans le but de dimensionner l'ensemble des pertes d'un câble complet. Enfin, les modèles numériques développés précédemment sont utilisé sur un exemple concret : le démonstrateur 10~kA fait à l'aide du conducteur MgB2 dans le projet BEST-PATHSThe work reported in this PhD deals with AC losses in superconducting material for large scale applications such as cables or magnets. Numerical models involving FEM and integral methods have been developed to solve the time transient electromagnetic distributions of field and current density with the peculiarity of the superconducting constitutive E-J equation. Two main conductors have been investigated for two ranges of superconducting cables. First, REBCO superconductors working at 77 K are studied and a new architecture of conductor (round wires) for 3~kA cables. Secondly, for very high current cables, 3-D simulations on MgB2 wires are approach and solved using FEM modeling. The following chapter introduced new development used for the calculation of AC losses in DC cables. The thesis ends with the use of the developed numerical model on a practical example in the BEST-PATHS project: a 10 kA MgB2 demonstrator
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Kirsten, André Luís. "Reator eletrônico para lâmpadas de descarga em alta pressão baseado no conversor biflyback inversor." Universidade Federal de Santa Maria, 2011. http://repositorio.ufsm.br/handle/1/8494.
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Coordenação de Aperfeiçoamento de Pessoal de Nível SuperiorThe study of the best utilization of high intensity discharge lamps deals with the great global concern with energy efficiency. Electronic ballasts are the current devices that can make the good use of high luminous efficacy and the long useful life of these lamps. This work aims to develop an electronic ballast to supply high intensity discharge lamps. In order to avoid the acoustic resonance phenomenon occurrence, the lamp is supplied with low frequency square waveform. Power control and voltage inversion stage in the lamp are developed by the biflyback inverter topology. The analysis and design of this topology were performed, as well as the development of resonant inversion methodology of the lamp voltage. It is proposed one study, qualitative and quantitative, of active converters to provide the power factor correction, and their integration with the biflyback inverter topology. Buck biflyback inverter topology is chosen to the implementation of practical experiments, in order to validate the present work. The converter modeling, considering the lamp dynamic, such as the stability analysis and theoretical control strategy of current and lamp power are presented. Experimental results show that the proposed electronic ballast has the follow characteristics: high power factor (0.97), low input current harmonic distortion, high efficiency (88%) and not visible occurrence of acoustic resonance phenomenon.
O estudo do melhor aproveitamento das características das lâmpadas de descarga em alta pressão vem ao encontro da grande preocupação mundial com a eficientização energética. Reatores eletrônicos são os dispositivos atuais que melhor aproveitam a alta eficácia luminosa e longa vida útil dessas lâmpadas. Este trabalho visa o desenvolvimento de um reator eletrônico para a alimentação de lâmpadas de descarga em alta pressão. De modo a não excitar a ocorrência do fenômeno de ressonância acústica, a alimentação da lâmpada é realizada através de forma de onda de corrente quadrada em baixa frequência. Os estágios de controle de potência e inversão da tensão na lâmpada são realizados pela topologia biflyback inversora. A análise e projeto desta topologia foram realizados, assim como o desenvolvimento de uma metodologia de inversão ressonante da tensão da lâmpada. É proposto um estudo, qualitativo e quantitativo, dos conversores ativos para correção do fator de potência, e a integração destes, com a topologia biflyback inversora. A topologia buck biflyback inversora foi escolhida para a realização de experimentos práticos para a validação do trabalho. A modelagem do conversor, considerando a dinâmica de uma lâmpada de descarga em alta pressão de sódio foi realizada. Assim como a análise da estabilidade e estratégias de controle da corrente e da potência na lâmpada. Os resultados experimentais comprovam que o reator eletrônico proposto apresenta as características desejadas de: alto fator de potência (0,97), atendimento da norma IEC61000-3-2 para o nível das harmônicas da corrente de entrada, elevado rendimento (88%) e não excitação visível do fenômeno de ressonância acústica.
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Leredde, Alexandre. "Etude, commande et mise en œuvre de nouvelles structures multiniveaux." Thesis, Toulouse, INPT, 2011. http://www.theses.fr/2011INPT0094/document.
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Les structures de conversion multiniveaux permettent de convertir en moyenne tension et forte puissance. Celles-ci sont construites à partir de cellules de commutations et permettent d’augmenter le courant et la tension en entrée ou en sortie. Ces structures sont appelées multiniveaux car les formes d’ondes des tensions en sortie permettent d’avoir plus de deux niveaux de tension différents. Les différentes structures peuvent être classées dans différentes catégories tel que la mise en série de pont en H, les convertisseurs multicellulaires série ou parallèle ou encore les structures utilisant le fractionnement du bus continu. Toutes ces structures ont des propriétés et applications différentes, même si certaines structures ont des propriétés communes. Il est aussi possible de créer de nouvelles structures en mixant les différentes structures de bases des différentes familles de convertisseurs multiniveaux ou en assemblant les structures de base de la conversion statique. Même si l’utilisation de structure de conversion multiniveaux permet de convertir à forte puissance, celle-ci n’est pas toujours aisée. En effet l’augmentation du nombre de niveaux ou de la tension d’entrée implique également une augmentation du nombre de composants semiconducteurs. Ceci peut être un frein à l’utilisation de convertisseur multiniveaux. Pour cela une nouvelle structure utilisant des composants partagés entre les différentes phases est proposée afin de limiter leur nombre. Un autre problème important lié aux convertisseurs multiniveaux est l’équilibrage des tensions des condensateurs du bus continu si celui-ci est composé de plus de deux condensateurs mis en série. Pour cela plusieurs solutions sont possibles : soit en utilisant une commande spécifique utilisant la modulation vectorielle, soit en utilisant des structures auxiliaires qui ont pour but d’équilibrer les différentes tensions des condensateurs. Dans une dernière partie ont été proposées de nouvelles structures qui permettent à la fois d’augmenter le courant de sortie et la tension en entrée en utilisant les principes des structures de base des convertisseurs multicellulaires série et parallèle. De plus, ces structures ont des propriétés intéressantes sur les formes d’ondes de sortie. De ces structures a été conçu un prototype permettant de valider les résultats de simulation. Une commande numérique implantée sur FPGA a été réalisée et a permis d’avoir des résultats expérimentaux intéressantsThis PhD Thesis deals with the study of new multilevel structures. At the beginning of this work, a new methodology to create new multilevel structures has been conceived. To evaluate the performances of these structures, there are many possibilities: number of output voltage levels, number of components, and the quality of the converters’ output waveforms. The list of criteria is not exhaustive. One technique to obtain an output multilevel waveform is to split the DC link in several capacitors. There is a limitation since putting more than two capacitors in serial connection leads to an unbalancing of these voltage capacitors. Several solutions are possible to balance these voltages. The first one uses the control of the structure in a three phase application, using a space vector modulation and minimizing the energy stored in the DC link. The second solution consists in using auxiliary circuits, which realize an energy transfer between one capacitor to another through an inductor. The drawback of this method is the high number of components. This problem can be reduced sharing some components between the three phases of the converter. The third part of this study is related to multicell converters, structures with very interesting good properties. New converter structures mix serial and parallel multicell converters, to obtain a hybrid converter with similar performances to the two basic converters. An experimental prototype was built to validate the results of the PhD. The digital control of this hybrid structure was made with a FPGA where two DSP processors were implemented
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Гаврилюк, Ігор Миколайович, and Havryliuk Ihor. "Розробка проекту лінії електропередачі з вставкою постій¬ного струму." Master's thesis, ТНТУ імені Івана Пулюя, 2019. http://elartu.tntu.edu.ua/handle/lib/29562.
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В дипломній роботі виконано дослідження можливих варіантів об’єднання несинхронних електроенергетичних систем та систем з різними стандартами регулювання частоти.
Метою роботи є розробка лінії електропередачі «Ковель – Хелм» з вставкою постійного струму для продажу електроенергії з України у Польщу.
Об’єкти, аналогічні спроектованому у даному проекті, можна впровад¬жувати і в інших елек-тричних мережах, що дозволить значно зменшити розміри синхронних мереж змінного струму, запобігти або обмежити каскадні відключення, підвищити коефіцієнт корисної дії електромереж і надійність електроенергетичних систем.In the diploma paper deals with the possibility of combining non-synchronous power systems and systems with different frequency control standards. The purpose of the work is to develop a Kovel-Helm transmission line with a DC insert for the sale of electricity from Ukraine to Poland. Objects similar to those projected in this project can be implemented in other power grids, which will significantly reduce the size of AC synchronous networks, prevent or limit cascade outages, increase the efficiency of grids and the reliability of power systems.
ПЕРЕЛІК УМОВНИХ СКОРОЧЕНЬ.................................................................... 7 ВСТУП .................................................................................................................…8 1 АНАЛІТИЧНА ЧАСТИНА ...............................................................................13 1.1 Призначення вставок постійного струму......................................................13 1.2 ВВППС – основні характеристики системи .................................................15 1.3 Варіанти застосування ВВППС .....................................................................16 1.4 Керування потужністю ...................................................................................17 1.5 Поведінка ВВППС в умовах виходу з ладу системи змінного струму......18 1.6 Вплив підключеної мережі змінного струму на ВПС .................................19 1.7 Споживання реактивної потужності .............................................................21 1.8 Висновки до розділу .......................................................................................23 2 НАУКОВО-ДОСЛІДНА ЧАСТИНА................................................................24 2.1 Пріоритетні напрями діяльності магістрального електромережевого комплексу.........................................................................................................24 2.2 Заходи шодо зниження комерційних втрат електроенергії ........................28 2.3 Перспективи передачі електроенергії за допомогою постійного струму .30 2.4 Основні причини використання ППС в ОЕС України ................................32 2.5 Висновки до розділу .......................................................................................35 3 ТЕХНОЛОГІЧНА ЧАСТИНА ..........................................................................36 3.1 Вибір напруги ліній електропередач постійного струму............................36 3.2 Вибір схеми вставки постійного струму.......................................................40 3.3 Перетворення й регулювання струму конверторами ..................................41 3.4 Вибір тиристорів .............................................................................................44 3.5 Система захисту тиристорів від перенапруг та перевантажень .................48 3.6 Система охолодження тиристорних модулів ...............................................50 3.7 Визначення кількості тиристорів у вентильних групах перетворювача ...52 3.8 Висновки до розділу .......................................................................................54 4 ПРОЕКТНО-КОНСТРУКТОРСЬКА ЧАСТИНА ...........................................55 4.1 Вибір раціонального січення проводів .........................................................55 6 4.2 Розрахунок споживання реактивної енергії перетворювачами..................56 4.3 Усунення впливу вищих гармонік напруги й струму у схемі ВПС...........60 4.4 Розрахунок фільтрокомпенсуючого пристрою............................................65 4.5 Активні фільтри...............................................................................................71 4.6 Висновки до розділу .......................................................................................74 5 СПЕЦІАЛЬНА ЧАСТИНА................................................................................75 5.1 Вибір трансформатора ....................................................................................75 5.2 Компенсація реактивної потужності.............................................................78 5.3 Вибір місця під’єднання компенсаційних пристроїв ..................................81 5.4 Розрахунок потужності компенсаційних пристроїв ....................................81 5.5 Зменшення струму несиметрії у вставках постійного струму ...................84 5.6 Струм к.з. на шинах високої напруги трансформаторів .............................86 5.7 Вибір обладнання ............................................................................................87 5.8 Висновки до розділу .......................................................................................92 6 ОБГРУНТУВАННЯ ЕКОНОМІЧНОЇ ЕФЕКТИВНОСТІ..............................93 6.1 Критерії економічної ефективності енергетичного виробництва..............93 6.2 Визначення капітальних затрат .....................................................................94 6.3 Вартість електроенергії ..................................................................................95 6.4 Розрахунок економічної ефективності..........................................................98 7 ОХОРОНА ПРАЦІ ТА БЕЗПЕКА В НАДЗВИЧАЙНИХ СИТУАЦІЯХ ...100 7.1 Заходи безпеки при обслуговуванні електроустановок ............................100 7.2 Захист персоналу від впливу електричних і електромагнітних полів .....103 7.3 Захист персоналу підстанції від наведених напруг ...................................106 8 ЕКОЛОГІЯ........................................................................................................108 8.1 Актуальність охорони навколишнього середовища..................................108 8.2 Вплив на людину електромагнітного забруднення довкілля ...................108 8.3 Вплив магнітного поля повітряних ліній постійного струму високої і надвисокої напруги на навколишнє середовище.......................................110 ЗАГАЛЬНІ ВИСНОВКИ ДО ДИПЛОМНОЇ РОБОТИ ...................................112 ПЕРЕЛІК ПОСИЛАНЬ .......................................................................................113
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Bendjoua, Jamel. "Contribution à l'étude de l'alimentation des machines électriques de fortes puissances : minimisation des ondulations de couple lors de l'alimentation par cycloconvertisseur." Vandoeuvre-les-Nancy, INPL, 1995. http://www.theses.fr/1995INPL119N.
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Ce travail porte sur la modélisation, la simulation, la commande du système cycloconvertisseur-machine synchrone et asynchrone et de la comparaison de leurs performances en terme d'ondulation de couple électromagnétique. On montre que la machine synchrone permet, en statique, d'avoir un couple moins ondulé. Par contre, la machine asynchrone présente un meilleur comportement dynamique lors du démarrage. Afin de limiter les harmoniques provoqués par le temps mort de sécurité, une deuxième horloge permettant d'imposer la durée du palier nul à une valeur fixe est proposée. Enfin, dans le but de réduire les ondulations du couple, une modification de la structure du cycloconvertisseur en ajoutant six thyristors de roue libre est étudiée. Cette modification a permis de réduire, d'une façon importante, les ondulations du couple de la machine synchrone fonctionnant à facteur de puissance unitaire
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Labouré, Eric. "Contribution à l'étude des perturbations conduites dans les alimentations continu-continu isolées." Cachan, Ecole normale supérieure, 1995. http://www.theses.fr/1995DENS0010.
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Ce travail s'inscrit dans une démarche générale de réduction des perturbations électromagnétiques émises par les équipements électriques. Il s'agit d'étudier les perturbations conduites générées par les convertisseurs statiques haute fréquence moyenne puissance dans l'optique de réaliser un outil d'aide a la conception prenant en compte ces phénomènes. Notre étude utilise comme support deux alimentations continu-continu isolées (alimentation flyback et alimentation forward) représentatives des problèmes rencontres. Après un bref rappel sur les normes et sur les équipements correspondants, un capteur de courant adapte a l'étude des perturbations électromagnétiques dans les convertisseurs statiques est présenté. Un des objectifs de l'étude est de pouvoir prédéterminer par simulation le niveau de perturbations d'un convertisseur. Pour cela, il est nécessaire de disposer d'un modèle électrique pour chacun des ensembles qui le constitue. Les modèles développés dans ce document concernent le transformateur et les composants a semi-conducteur (diode et igbt). Afin que ces modèles soient simples et facilement intégrables a un logiciel de simulation de type circuit, des modèles comportementaux issus de la littérature sont utilises. Notre travail consiste à adapter ces modèles à notre étude, c'est à dire à obtenir une bonne représentation des composants dans la bande de fréquence 10khz-30mhz. Le comportement des alimentations flyback et forward est alors analyse, essentiellement par simulation. A partir d'un schéma élémentaire (composants idéaux) de l'alimentation, les différents éléments parasites sont ajoutes étape par étape. L'analyse des modifications observées dans le domaine temporel et fréquentiel permet de cerner les diverses origines des perturbations. Cette démarche est reprise avec l'introduction d'un écrêteur puis d'un calc non dissipatif. Les résultats obtenus par simulation sont compares aux résultats expérimentaux afin de valider l'ensemble de l'étude (modèles et résultats d'analyse). Enfin, divers moyens de reduction des perturbations sont analyses. Tout d'abord deux moyens de reduction a la source sont proposes. Puis diverses solutions de reduction des couplages sont présentées. Finalement, le filtrage est abordé et les diverses cellules usuelles sont étudiées et comparées
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Sahay, Shubham. "Design and analysis of emerging nanoscale junctionless fets from gate-induced drain leakage perspective." Thesis, 2018. http://localhost:8080/xmlui/handle/12345678/7579.
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Wu, Chin-Ming, and 吳智敏. "Performance of High Power LED Thermal Dissipation." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/53144410513704616153.
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碩士中華大學
機械工程學系碩士班
98
The purpose of this study is to remove the 90μm thickness of sapphire substrate of LED and the epitaxial layer (EPI) still maintains its integrity. The epitaxial layer of LED was then put directly on diamond and silicon dissipation plate. The thermal performance of LED was observed. In this study, how to fully remove the sapphire substrate is the key process. In experiment, the thermal dissipation was first tested when the general LED placed on the graphite or diamond dissipation film. Due to the characteristics of sapphire substrate, the effect of thermal dissipation was not obvious. Therefore, to increase the effect of thermal dissipation of LED devices, the removal of sapphire substrate will be the key. To remove the sapphire substrate, LED was first attached on a plate that can be manipulated by hands. Sandpaper with #600 was first used in grinding processes until the thickness of substrate was reduced to about 60μm; sandpaper with #1000 was then used to reduce the thickness of substrate to about 40μm. Sandpaper with #2000 was utilized as the final grinding process to remove all the sapphire substrate. It is important to investigate the specimen under microscope through grinding to check the thickness of substrate which is removed. In grinding, it should be very carefully to control the grinding speed. Low speed is better in this process. When the specimen with 1mm2 in square put on the silicon dissipation plate after the sapphire substrate was removed, it was fond that the measured junction temperature can be reduced from 51.1°C to 44.9°C comparing to that general LED without removing the sapphire substrate at the same condition at 1.5W power. The thermal resistance (RT) at this condition was measured to be 15.3°C/W. On the other hand, it was fond that the measured junction temperature can be reduced from 47.8°C to 40.9°C comparing to that general LED without removing the sapphire substrate at the same condition at 1W power. The thermal resistance (RT) at this condition was measured to be 17.1°C/W. When the specimen with 1mm2 in square put on the diamond dissipation plate after sapphire substrate was removed, it was fond that the measured junction temperature can be reduced from 51.1°C to 43.8°C comparing to that general LED without removing the sapphire substrate at the same condition at 1.5W power. The thermal resistance (RT) at this condition was measured to be 14.8°C/W. However, it was fond that the measured junction temperature can be reduced from 47.8°C to 40.2°C comparing to that general LED without removing the sapphire substrate at the same condition at 1W power. The thermal resistance (RT) at this condition was measured to be 16.6°C/W.
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Lee, Kuan-liang, and 李冠良. "Heat Dissipation for High Power Supply of Network Servers." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/34ew46.
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碩士國立臺北科技大學
能源與冷凍空調工程系碩士班
102
High capacity power supply transforms AC to DC current, and is an essential part of network servers. There are mainly two types of high power supply such as LPS and SPS, due to the difference in the constructions. In comparison SPS is thinner and smaller and has more stable output, and is therefore commonly used in internet servers. The heat dissipation problem of a SPS high power supply of 1600W-12V output was analyzed in this thesis. Flotherm program was used to construct the simulation model of the 1600W power supply. The overall power supply heat sink design was analyzed. The computed results were compared to the actual testing for verification of the simulation. Further simulation of air flow and temperature distribution was carried out to study the enhancement of heat dissipation for the power supply, with cost and space consideration. Heat dissipation enhancement was investigated by varying the shape of heat sink, air flow path, openings at the case, conduction to server case, etc. The results show that the temperature at the essential components such as (BD1=Bridges), (Q2) and (D2) can decrease by 11.5%. The stability and reliability of power supply can be improved at the same time.
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Jeong, Taikyeong Ambler Tony. "Dynamic CMOS circuit power dissipation methodology in low power high bandwidth chip design." 2004. http://wwwlib.umi.com/cr/utexas/fullcit?p3143895.
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Jeong, Taikyeong 1969. "Dynamic CMOS circuit power dissipation methodology in low power high bandwidth chip design." 2004. http://hdl.handle.net/2152/12777.
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Liao, Pei-Hsuan, and 廖沛軒. "The High-Performance and Low-Power Dissipation Output Driver Design." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/25824318588679529931.
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碩士淡江大學
電機工程學系碩士在職專班
99
Due to the productivity growth of computer relevant products and based on the nowadays environment of respecting to the energy conservation, low power dissipation of computer chipset becomes one of the development goals. This paper is to address a new type of CMOS buffer which can be compatible in all the chipset design in computer relevant products. This new type of CMOS buffer has two main features. Firstly, this Feedback- controlled Split-path CMOS Buffer can distinguish the output signals, and then depart the path. In another words, it would eliminate the power dissipation of output short-current if the CMOS buffer has this inverted-delay-unit. Secondly, it has Bootstrapping Low-Voltage Driver features. This driver is to combine bootstrapping large capacitor to the MOSFET switch speed more than fast, it would eliminate the power-delay product dissipation. The simulated environment in this paper is based on the manufacture process of 0.35μm in TSMC and Intel ICH10 Chipset (14MHz, 33MHz and 48MHz) as main simulated frequency. The simulated range of voltage is from 3.3V to 1.8V (0.5V is the interval.). The simulated range of temperature is from -40℃ to 140℃ (10℃ is the interval.). As compared this CMOS buffer with others in 14MHz, 33MHz and 48MHz. At 1.8V this new type of CMOS buffer than the best of power-delay product dissipation and its value were 10.3%, 10.8%, 9.1%.
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Lin, Min-Hsien, and 林旻賢. "Heat Dissipation and Thermal Measurement Analysis of High Power LED." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/15802122354071208926.
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碩士國立交通大學
平面顯示技術碩士學位學程
98
In the light-emitting diodes (LEDs) on the research and development, with the development of technology and process improvements, LED applications are no longer only applies to intensity directivity of light source, but rather toward the development of lighting applications, they will be the main components of human lighting applications in the future development. When the trend of the increasing popularity of LED applications, which also represents the efficiency of LED has been increased gradually. With lighting in the LED market, most are used in high-power LED applications, high-power LED current efficiency of about 60 ~ 70lm / W, The efficient reason of LED improvement, mainly from the chip, packaging, materials, process capability enhancement, and the present high-power LED chips used in the types of chips can be divided into vertical dies and horizontal dies, and the manufacturing process these two ways differ due to different chips. This thesis will be high-power LED as the main focus of the analysis, and targeted at the two different structures of the chip – the analysis of vertical dies and horizontal dies on thermal resistance and optical efficiency, and then by the colloidal silver of different materials and printed circuit board (PCB) material to do a comparative analysis, it is thought that this analysis will allow us to understand the demonstrated results from the collocation of different chips with different colloidal silver and the PCB , and thus get the best of high-power LED.
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Huang, Zheng-Hong, and 黃正宏. "Experimental Investigation of Heat Dissipation Factors for High-Power LEDs." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/685bde.
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碩士國立虎尾科技大學
機械設計工程研究所
101
Heat generations were inevitable transport phenomenon of high-power LED lighting. While high-power LEDs in operation can produce high luminance, but they also generate significant heat at the same time. The optical output of the LED is sharply degraded with the increase in junction temperature because the high temperature significantly influences the reliability and durability of the LED. The heat dissipation factor, Kh, for a lighting device is defined as heat dissipation from the lighting to total electrical input power of the lighting. It will be beneficial and critical to modeling and simulate thermal designs of lighting if the Kh factor of the specific LEDs is precisely obtained. In this study, a methodology is proposed and experiments are conducted to find the LEDs heat dissipation factors. Experiment procedures are changing the input powers to LEDs, and then gathering information by related instruments for the whole transient to steady states. Experimental results showed that, for two different brands of LEDs under test, different values of heat dissipation factor were found, and the optical outputs of luminous flux were affected by the value of heat dissipation factor. By using the simple method to measure the heat dissipation factor, the theoretice luminous flux can be evaluated; and comparing it to the luminous flux evaluated by the method of using a forward current model and a junction temperature model, the absolute error between these two results is less than 10%. It is expectable that the measured Kh factor will be helpful to thermal designs and characterizations of optical-thermal interdependence of LED lightings.
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Li, Ruiming. "Performance and power dissipation optimizations for high-speed VLSI interconnect designs /." 2005. http://proquest.umi.com/pqdweb?did=1306826781&sid=16&Fmt=2&clientId=10361&RQT=309&VName=PQD.
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Wu, Jia-Lin, and 吳嘉霖. "Heat dissipation analysis of automotive high power LED headlight using ANSYS." Thesis, 2019. http://ndltd.ncl.edu.tw/cgi-bin/gs32/gsweb.cgi/login?o=dnclcdr&s=id=%22107NCHU5693021%22.&searchmode=basic.
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碩士國立中興大學
精密工程學系所
107
Due to the trend of eco-awareness, high-powered LED Lighting equipment has been a research target in the field of automobile lighting. By understanding the effects of temperature, we will develop the technical design of heat dissipation for the system of high-powered LED car headlights. Integrating [ heat transport analysis ] and [ structural stress ] , computer-aided simulated techniques, we expect to manage the heat dissipation more effectively to reach the goals of greater efficiency of the bulb, and improve the related techniques of system of high-powered LED automobile headlights. This study uses the comparison of confined space and open space in the lampshade, and takes into account the quality of heat transfer in the heat tube, in order to apply to the system of automobile headlight heat dissipation. Comparing the design mechanisms and set parameters of heat dissipation, and adopting the best choice. We examine the results of the experimentation on confined space and open space , and the cooling provided by the airflow. Making use of counting finite elemental analysis (ANSYS) to select the best heat dissipation design mechanism. From the confined space and open space in the lampshade as the first test reference, and other subsequent conditions are also added to the simulation, such as air source temperature, heat sink shape, heat pipe conductivity. The simulation results show the condition of natural convection, the open lampshade space is more conducive to the cooling of the LED chip, and the temperature change reaches 12.3°C.
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Tseng, Wang-Ken, and 曾旺根. "HIGH POWER LIGHT EMITTING DIODES PACKAGE TECHNOLOGY AND FOR ANALYSIS HEAT DISSIPATION." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/7xd2qm.
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碩士國立臺北科技大學
機電整合研究所
100
The articles presented herein are the research and study of LEDs sealing package technology improvement, by various medium-elements and related parameters affect the critical working conditions, by high temperature environment caused by high-current conjunction.By the technology of PWM (Pulse Width Modulation) pulse bandwidth to control and modulate the timing of power-on, power –off as similar as power input DC power-liked, in order to reduce the thermal generated by power connection constantly. The method is able to prolong the life of LEDs as well as power consumption saving.According to the latest research and tests managed in laboratory, to trigger the LED lighting-on by a kind of power as DC-liked, high frequency as 1000HZ adjust the duty cycle as 80%. The phenomenon of lighting flicker could be eliminated Taking the same LED go through real DC power (pure DC) connect with LED lighting on, and then by the latest development PWM power connection, the LED is able to get 3-4 degree C lower in the same working condition. That is obviously, the way is able to get power saving and prolong the life of LED by thermal dissipation as mentioned above. Except external control to have power saving and LED life prolonging, there is another method by internal modification. That enlarges the pitch between the chips. The surface of substrate is able to get around 6 degree C reduction subject to the pitch of chips enlarge each 1mmx1mm. Heat sink of LED device could be simplified. According to the literature and reports by Mr. Morrisn in 1992 that convection in a nature environment, by a sufficient air circulation space, thin wings correspond a thicker base could be the best design applied for high power LED. The K coefficient Considering the TSP (utilize the characteristics of voltage and temperature change) the K-coefficient should be treated as key-factor That can show the variation of Tj ( temperature on junction) Instruments as Power Supply, Wave Generator , Silicon Heat Plate, Power Transistor, Thermal Meter, Wire of Thermo coupler Multi-meters all are able to measure the K value within a short period. We are able to identify the reflection and influence between the K value and R value ( thermal resistance). That will come to a mathematic formula showing both values are inverse proportion, K value raise up then R value down. This presentation will bring a conclusion to utilize the advantages of mentioned above, as DC-power-liked connection, proper heat sink and modify the pitch of chip (enlarge) then we are able to get power consumption saving by 20% approximately, lower temperature by 3-4 degree C, the same meaning prolong the life of LED and bring cost reduction for all devices.
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Huang, He-Chun, and 黃赫群. "Optimal design of high power LED heat dissipation module using Taguchi method." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/60171443327231210054.
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碩士中原大學
機械工程研究所
101
The conversion efficiency of the LED is around 15 percent to 25 percent and the rest of the energy will be dissipated in the form of heat .If the heat didn't dissipate properly ,it will lead to high junction temperature which will lower the luminous flux and reduce the lifetime of LED. The purpose of this study is to find the optimal factor combination by using Taguchi method and simulation software ANSYS CFX. Taguchi method is used to investigate heat dissipation modules attached to the 100W, 120W, and 140W high power LEDs. The optimal combination of the factors for three different input heat watts are all the same ; two of the most dominating factors for reducing the junction temperature are led package type and radius of the heat sink pin. After finding three different set of optimal factor combinations, single-factor analyses are conducted for the relation between the effective k value and the junction temperature. The result shows that the temperature drops relatively huge for effective k value ranging from 250 W/m-k ~ 2500 W/m-k compare to the k value ranging from 2500 W/m-k to 7500 W/m-k, the range of temperature difference for k values within 2500 W/m-k to 7500 W/m-k are all less than one degree Celsius . The results can be used as a reference for the commercial design of the LED lamp.
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Su, Shiou-Hung, and 蘇修弘. "A Study on the Heat Dissipation for High-Power LED Using Microchannels." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/07766965372651404374.
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碩士中原大學
機械工程研究所
101
The research presented in this thesis studied basic heat exchange of microchannels, and discussed thermal experiments and numerical analyses by using microchannel heat exchangers attached to a 20W high-power LED module. This LED module was set on the microchannel heat exchanger module as a basic experimemtal to obtain the surfaces of the LED chip, the external temperature of microchannels. In this study, under constant surface heat transfer condition, the distributions of velocity and temperature fields inside the microchannel were simulated and analyzed. The software of ESI-CFD-ACE+ was used for numerical simulations. The errors between the results obtained from the experiments and those obtained from the simulations were in the range of 0.4%-7.4%, with an average error of 3.98%. The silicon wafers used in the experiments were fabricated by semiconductor manufacturing process, and the working fluid was de-ionized water, with the Reynolds number ranging from 94 to 1260. The experimental results showed that for different microchannel heat exchangers, the curves of LED chip temperature versus the Reynolds number of the flow were reasonable. The resulting temperature distributions were more uniform within the microchannel, and as a result, dissipated more heat from the LED chip. The input power was 20 W, and by using the microchannel heat exchangers, the LED chip surface temperature has dropped significantly. The LED chip temperature dropped from 85 ℃ by using the single fin-type heat sink to 47 ℃ by using the microchannel heat sink. Thus using the microchannel heat sink has shown to be effective in help solving the heat concentration problems associated with the LED chips.
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Lin, Chun-Jui, and 林俊睿. "Heat Dissipation Model of a High-Power LED Headlamp for the Automobile." Thesis, 2019. http://ndltd.ncl.edu.tw/handle/74rqec.
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碩士國立中興大學
精密工程學系所
107
With the improvement of LED packaging process capability and cost, and the advantages of high efficiency, long life, light and short, easy to design, etc., it has been widely used in automotive lighting sources in recent years, and has begun to replace the old halogen. The design and development of lamps and xenon headlamps has become the goal of active research by various manufacturers in the market in the future. However, due to the luminous efficiency and lifetime of the LED itself, it will decrease as the temperature of the wafer increases, and the package structure of the LED is not heat-resistant. When the junction temperature of the LED chip is too high, the wafer itself and the package tape will be come to permanent damage.Therefore, how to design an effective heat dissipation method to improve the LED luminous efficiency and life will be an important key to the application of high power LEDs. This study used computational fluid analysis software to analyze and heat-dissipate the original model of commercially available high-power LED headlamps. By adding the grooved heat pipe and the fan, and changing the material parameters of the LED package substrate and the circuit board, the change of the junction temperature of the LED chip is observed, and the heat dissipation efficiency of the heat dissipation module is discussed. The results show that under the forced convection, the heat transfer coefficient of the LED heat sink substrate and the PCB can be effectively reduced under the forced convection, so that the junction temperature of the LED chip can be effectively lowered, and the high-power LED headlight is safe. Maintain component reliability over temperature.
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Chen, Chun-Chih, and 陳軍志. "Thermal Fluid Experiments for Ultra-High Power COB LED Graphene Heat Dissipation." Thesis, 2018. http://ndltd.ncl.edu.tw/handle/bvr27u.
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碩士國立勤益科技大學
冷凍空調系
106
Solid-state lighting (LED) is a green energy and eco-friendly lighting technology. It has many advantages such as high brightness, long life, strong structural strength, and fast response time. The luminous efficiency of LED is about between 15% and 20%, and the remaining between 80% and 85% is converted into heat energy, causing the temperature of LED Tj to be too high and resulting in light decay. Heat dissipation is a necessary condition for maintaining life. In this thesis, the ultra-high power COB LED is used as the experimental objective in natural convection and forced convection cooling are adopted. The quantitative experiments such as flow field observation and temperature measurement are used to explore and analyze the heat dissipation of LED. To use graphene materials with a thermal conductivity of up to 5,300 W/m_K, blended thermal pastes, pastes of different concentrations (10%, 15%, and 20%) and different air speed (0.5m/sec, 1.0m/sec, 1.5m/sec, 2.0m/sec, 2.5m/sec, and 3.0m/sec) experiments, the experimental found that 15% concentration has better heat dissipation effect, while the increase or decrease of concentration has no obvious improvement on heat dissipation capacity. The heat can be taken away by the high is also increased and the time required to reach the steady state is reduced. In the observation of the flow field, the formation of thermal buoyancy can be found during natural convection. When the air convection is forced, as the air speed rises, the thermal boundary layer destruction, the disappearance of the low-pressure retention zone, the effect of the recirculation on the heat sink module is reduced, and the heat dissipation effect is improved.
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Ye, Zhong-Ting, and 葉重廷. "A High-Performance/Low-Power Mixed Static/Dynamic Circuit Synthesizer." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/46355007191199355412.
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碩士大葉大學
資訊工程學系碩士班
93
Because domino logic design offers smaller area and higher speed than complementary CMOS design, it has been very popularly used to design high-performance processors. There are several research works on high-performance mixed static/dynamic circuit; but most of the works focus on the theory discussion without practical results are presented. In this thesis we try to establish the cell based design flow of the mixed/merged static/dynamic circuit synthesis, which has skew tolerant, low-power and high-performance characteristics. And, the real chip implementation and silicon proven will be validated finally. In this work, there is three major targets are got: Target-one, we propose a static-dynamic-static(SDS)high-performance/low-power mixed/merged static/dynamic circuit design techniques. Target-two: the supported synthesizable design flow has been established for Target-one; we focus on the skew-tolerant issue of this target by using current CAD tools. Target-three, two noise-alleviation (charge sharing, crosstalk) domino cell libraries are generated to support the cell-based synthesis CAD design tools. Key word：mixed/merged，static circuit，dynamic circuit，cell base
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Bhattacharyya, Prasun. "Design of a novel high speed dynamic comparator with low power dissipation for high speed ADCs." Thesis, 2011. http://ethesis.nitrkl.ac.in/2770/1/209EC2123_PRASUN_BHATTACHARYYA_c.pdf.
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A new CMOS dynamic comparator using dual input single output differential amplifier as latch stage suitable for high speed analog-to-digital converters with High Speed, low
power dissipation and immune to noise than the previous reported work is proposed. Backto- back inverter in the latch stage is replaced with dual-input single output differential amplifier. This topology completely removes the noise that is present in the input. The structure shows lower power dissipation and higher speed than the conventional comparators. The circuit is simulated with 1V DC supply voltage and 250 MHz clock frequency. The proposed topology is based on two cross coupled differential pairs
positive feedback and switchable current sources, has a lower power dissipation, higher speed, less area, and it is shown to be very robust against transistor mismatch,
noise immunity. Previous reported comparators are designed and simulated their DC response and Transient response in Cadence® Virtuoso Analog Design Environment using GPDK 90nm technology. Layouts of the proposed comparator have been done in Cadence® Virtuoso Layout XL Design Environment. DRC and LVS has been checked and compared with the corresponding circuits and RC extracted diagram has been
generated. After that post layout simulation with 1V supply voltage has been done and compared the speed, power dissipation, Area, delay with the results before layout and the superior features of the proposed comparator are established.
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Tsai, Liang-Te, and 蔡良德. "Heat Dissipation Mechanism Analysis of a High-Power LED Headlamp for the Automobile." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/24723779170190966491.
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碩士國立中興大學
精密工程學系所
105
Due to the progress of packaging capacity for the LED industry, modern LED technologies had reached cost reduction, high efficiency, quick response, long lifetime, thin and small, easy to design and many other advantages. Recently, LED has been widely used in the application of automotive lighting as the light source, and it began to replace the old Halogen lamps and High Intensity Discharge Lamp. The study of LED lightening for automobile draws lots of attention from the research and development of automobile industry and manufacturing. However, during the lightening operation of LED, the chip junction temperature rise can reduce the luminous efficiency and lifetime of LED. Moreover, the LED package structure is not heat resistance. Therefore, when the LED chip junction temperature reaches too high, the chip and the packaging material will cause the permanent damage. Overheating is the main problem in the application of the high power LED. To improve stability and lifetime span of the high power LED headlamp, heat dissipation mechanism design is the significant issues. In this study, the CFD software is used to study the original model of commercial high power LED headlamps. It is analyzed and designed for the heat dissipation. By adding a combination of groove heat pipe design and heat sink, changing the LED packaging substrate and PCB material parameters, we observe the LED chip junction temperature and to discuss the design of thermal dissipation module for heat dissipation. Our simulation results show that under the condition using the high heat conduction coefficient of the substrate and the PCB and combination of groove heat pipe and heat sink will result in lower the chip junction temperature, and maintain high power LED headlamps in the safe temperature range. In addition, with the design of a flat-panel heat sink with heat pipe design can speed up the internal flow through the LED chip junction and can lower its temperature than the previous structure to achieve better safe working temperature.
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Chang, Yi-Te, and 張毅德. "A Study on the Heat Dissipation of High Power LEDs by Piezoelectric Fans." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/ajv28h.
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碩士中原大學
機械工程研究所
99
Piezoelectric fan is belonging to a kind of micro-component of cooling device. It uses the piezoelectric effect to drive the fans and then produce the airflow to cool the heat source. This fan is of low power consumption, small size, and low noise. Piezoelectric fan is suitable for thermal management of miniature electronic device. An experimental method was used in this research. The piezoelectric fan was mounted on an opening space and a LED lamp which is fixed on the straight-type heat sink is used as the heat source. The thermal performances of piezoelectric fan at different positions were observed. The results show that the cooling capacity increases with bigger tip displacement and larger resonant frequency. Besides, the effect of resonant frequency outweighs that of tip displacement. The temperature of the LED lamps can be kept under 90℃ with the optimum location of the piezoelectric fan. Furthermore, the results also show that the placement of the piezoelectric fan is one of the important parameters affecting the cooling performance of the heat generating device. In the horizontal orientation, where the swing direction and the fin direction are in parallel, the optimal dimensionless depth of fan position is 0.6 and dimensionless height of fan position is 0.4 but they are 0.3 and 0.04, respectively for the vertical orientation. In general, the thermal performance decreases while the height of fan position increases.
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Hsieh, Tsung-Han, and 謝宗翰. "A novel heat-dissipation method for high power LED streetlights using thermoelectric generators." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/98927731039863803498.
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碩士國立中正大學
光機電整合工程所
97
Owing to the Light Emitting Diode (LED) with the advantages of high brightness,less power consumption, long lifetime etc, it gradually becomes the development focus of lighting device in the future. In recent years, LEDs were aimed at the development of high power efficiency. However, such a situation always leads to an unavoidable waste-heat problem and causes an adverse effect on LED including the brightness decay and shortened lifetime. In dealing with heat-dissipation for highpower LED, most of methods rely on the heat dissipation plate, drilling holes, heat pipe, and adding isothermal vapor chamber, etc. The thermoelectric generators made of thermoelectric materials not only could solve the heat-dissipation problem of high power LED streetlights, but also effectively transform the waste heat to renewable electricity. Basing on the statement mentioned in the above, different structures using rapid heat-dissipation device collocating with thermoelectric generators were fabricated and applied on the high power LED streetlights to study the efficiency of rapid heat-dissipation and the electricity from transformed the waste-heat. Evidence indicated that the thermoelectric generator indeed acts the kernel technology for waste-heat transformed to renewable electricity. By integrating the thermoelectric generator with heat-conduction, heat-dissipation material, and heat-dissipation device, it not only could lead the 60W LED streetlight to reach the lowest LED junction temperature (48℃), but also obtain a renewable electricity (70.2mW) by transforming the waste-heat from high power LED streetlights.
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Chien, Kun-Cheng, and 簡坤誠. "Fabrication and Analysis of Heat Dissipation Modulefor High-Power Light Emitting Diode Lamps." Thesis, 2008. http://ndltd.ncl.edu.tw/handle/48968917747434607960.
Full textAbstract:
碩士淡江大學
機械與機電工程學系碩士班
96
High-Power Light Emitting Diode (LED) has rapidly developed in recent years from indicators to illumination applications. Thermal management of these solid-state lighting is a critical design factor for the long-term reliability and luminance effect. Fabrication and analysis of heat dissipation module for high-power LED lamps are studied in this thesis. Results of the designed modules show that waste heat can be dissipated efficiently. The modules in this research are built by using the mature technology of heat pipe and heat sink. Through the research with ICEPAK software, several CFD models are established to compute and analyse for the modules under natural convection. According to the design parameters from the simulation results, a series of heat dissipation modules are manufactured in practice. The fabricated modules are bulb style (12W), outdoor landscape lighting lamp (12W and 14W), multi-layer structure (25W), and multi-chip LED streetlamp (120W). Input power, temperature distribution and illumination are measured in the experiment. Analyses of multi-chip LED streetlamp with heat dissipation module are discussed. The better efficiency is occurred in the case of non glass-lampshade module driven by power of 120 watts. The average temperatures of copper slot and lamp shell are 56.13℃ and 28.9℃ respectively, the average total thermal resistance is 0.24℃/W, and the average illumination in central position is 390lux under thermal steady-state. It’s apparent that how to enhance the efficiency of natural convection is still a challenge for high-power LED application. And to provide uniform illumination output could be another critical consideration for future lighting products.
36
Wu, Hsueh-Han, and 吳學翰. "A study on the heat dissipation of high power multi-chip COB LEDs." Thesis, 2012. http://ndltd.ncl.edu.tw/handle/50335354004643808586.
Full textAbstract:
博士國立臺灣科技大學
機械工程系
100
Five different chip gap of multi-chip COB (chip on board) package of high power LED components were compared by the chip temperature and thermal resistance to evaluate the thermal performance of LED in this study. The chip temperature was measured not only by a IR camera but also the Computational Fluid Dynamics (CFD) simulation software for comparison. Furthermore, the effects of different heat slug, the thickness of heat sink and the chip sizes to the high power LED components chip temperature were discussed. Experimental results show for power consumption of 7.94 W (350 mA) the chip temperature of A, B, C, D and E-Type structure were 84.32℃, 82.87℃, 81.91℃, 81.36℃ and 81.20℃, respectively. The chip temperature difference between the A-Type and E-Type structure were 3.12℃. Thus, a chip with a smaller gap has a higher chip temperature and more thermal resistance. The gap of GaN-base chip increased from 0.5 mm to 2.0 mm result in heat dissipation increased efficiently. Optical performance analyses show that the LED with a larger chip gap has higher lumens and higher luminous efficiency. Thus, higher chip temperatures reduce the optical performance of high power LEDs.
37
Velagaleti, Silpakesav. "A Novel High Speed Dynamic Comparator with Low Power Dissipation and Low Offset." Thesis, 2009. http://ethesis.nitrkl.ac.in/1376/1/207EC211_THESIS.pdf.
Full textAbstract:
A new fully differential CMOS dynamic comparator using positive feedback suitable for pipeline A/D converters with low power dissipation, low offset, low noise and high speed is proposed. Inputs are reconfigured from typical differential pair comparator such that near equal current distribution in the input transistors can be achieved for a meta stable point of the comparator. Restricted signal swing clock for the tail current is also used to ensure constant currents in the differential pairs. Nearly 18mV offset voltage is easily achieved with the proposed structure making it favorable for flash and pipeline data conversion applications. The proposed topology is based on two cross coupled differential pairs positive feedback and switchable current sources, has a small power dissipation, less hysteresis band, less area, and it is shown to be very robust against transistor mismatch, noise immunity. Test structures of the comparators, designed in GPDK 90 nm are measured to determine offset power dissipation and speed with 1.8 V are compared and the superior features of the proposed comparator are established.
38
Campos, Alexandre. "High performance static converters for series compensation of industrial power systems." Thesis, 1994. http://spectrum.library.concordia.ca/3409/1/NN97651.pdf.
Full text
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Chung, En-Chih, and 張恩誌. "SRAM with high static noide margin and low standby power consumption." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/52570752519725174692.
Full textAbstract:
碩士修平技術學院
電機工程研究所
99
This paper describes a new circuit approach for a Static Random Access Memory （SRAM）with high Static Noide Margin（SNM） and low standby power consumption comprising a memory array, a plurality of control units and a standby start-up circuit. The memory array comprises a plurality of rows of memory cells and a plurality of columns of memory cells. Each row of memory cells consists of a control unit, and each memory cell consists of a NMOS write selection transistor M3, two NMOS driver transistors M1 and M2, two PMOS load transistors P1 and P2, two NMOS read selection transistors M4 and M5, as well as two control inverters using PC1 with MC1 and PC2 with MC2. The key point is that the control unit is connected to the sources of the said NMOS driver transistors in each row. The control unit controls the source voltages of the said NMOS driver transistors for resolving the difficulty of write-logic-1 operation and for reducing leakage current of memory cells. In a write mode, the source voltage of near bit-line driver transistor is equal to a first preset voltage larger than a ground voltage and another driver transistor is the ground voltage to solve the write-logic-1 problem. In a stand-by mode, the source voltages of the said NMOS driver transistors are equal to a second preset voltage larger than a ground voltage to reduce leakage current. In other modes, the source voltages of the said NMOS driver transistors are the ground voltage to maintain read stability. Moreover, the back gate of driver transistor M1 is connected to output of the control inverter PC1 and MC1, and both the back gate of driver transistor M2 and the back gate of write selection transistor M3 are connected to output of the control inverter PC2 and MC2 , therefore the SNM can be improved. Furthermore, the standby start-up circuit can speed up the proposed SRAM with improved SNM and low standby power consumption reaching a standby condition. Based upon the verifications employing TSMC 90nm CMOS process, the proposed SRAM with improved SNM and low standby power consumption can resolve the difficulty of write-logic-1 operation and they also come with advantages like less standby power as well as good SNM. In addition, the proposed SRAM with improved SNM and low standby power consumption can be applied to guarantee acceptable results even a supply voltage below 1.0V while employing TSMC 90nm CMOS process.
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Hong, Jia-Wei, and 洪家偉. "Applications of Nanomaterials to Die Bonding and Thermal Dissipation of High Power Light Emitting Diodes." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/04543330392086823713.
Full textAbstract:
碩士崑山科技大學
電子工程研究所
98
Light-emitting diode (LED) is a function of energy-saving green energy and carbon reduction products, which can save more power and have longer life than the traditional light source. However, the high power LED is a lighting component of high heat generation, producing much larger heat than the traditional LED under high illumination. On the other hand, the LED by the small size of grains, thus making high-power LED heat density is very high, because of high power LED hot most of the surface are concentrated in the P-N junction, resulting in LED components overheating, overheating will affect the high-power wavelength shift with the optical characteristics of LED degradation, and the LED components overheating, will result in coefficient of thermal expansion of components is not stability, high mechanical loads between components will stress the damage. Therefore, this thesis is to improve the junction temperature of LED die attaching by using carbon nanotubes and Silicon Carbide. As both carbon nanotubes and silicon carbide thermal conductivity is about 3000 ~ 6000 (W /m‧K) and 300 ~ 380 (W /m‧K), so this study used carbon nanotubes and silicon carbide doped within the epoxy resin to resolve the thermal conductivity problem of LED for junction temperatures. In this experiment, measuring the junction temperature using forward bias voltage can see that the Epoxy is about 123℃, epoxy doped silicon carbide is about 99℃ and Epoxy doped COOH-CNT/SiC is about 93oC.From above the data that carbon nanotubes doped in epoxy device that significantly reduces the junction temperature of high power LED is 30℃. Such device improved the thermal dissipation of high power LED by up to 24%.
41
HUANG, PO-HSIANG, and 黃柏翔. "Effect of The Heat Dissipation and Reliability for High-power LEDs with Different Die Bonding Processes." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/376fnv.
Full textAbstract:
碩士明新科技大學
光電系統工程系碩士班
105
LED from a small electronic component, the development has become the world belong to the objects of the new production line. After 2009, more rapid growth in TV backlight and lighting applications market, create energy efficiency in technology and other factors have led to the growth, attracting manufacturers continue to invest to expand plant. In recent years, LED power boost, the accumulated heat is also getting higher and higher, the thermal spreader is not out of recession and lead to life LED luminous efficiency is reduced and the color temperature to produce the main reason for the change. LED heat conduction path from the inside to the outside, extending from the wafer, plastic timber, cups, brackets to the heat sink, the general conventional packaging methods most commonly used is the use of a solid crystal glue holding the wafer, if the solid crystal gum trouble heat removal, solid crystal plastic will lead to aging, yellowing, or bad, this paper investigate solid crystal plastic material of different thermal conductivity, the manufacturing process to make different thickness of plastic packages for LED brightness and thermal impact.
42
Chang, Chih-Hsiang, and 張志祥. "Fabrication of Carbon Nanotube and Its Application to Thermal Dissipation of High Power Light Emitting Diode." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/89943751884674307494.
Full textAbstract:
碩士崑山科技大學
電子工程研究所
97
High power light-emitting diode (LED) is an illuminating light source of environmental protection, which can save more power and have longer life than the traditional light source. However, the high power LED is a lighting component of high heat generation, producing much larger heat than the traditional LED under high illumination. On the other hand, because of the small LED package and the mold-filling plastic effect, the heat produced by lighting the LED is accumulated around the P-N junction, which leads to the decreases of luminance and life, the drift of wavelength. Due to uneven thermal expansion coefficients in the LED, large enough thermal stresses caused by the high temperature result in the LED damage. Consequently, how to improve the heat dissipation becomes an important issue in increasing the efficiency of the LED. Therefore, this thesis is to improve the junction temperature of LED die attaching by using carbon nanotubes. Due to high thermal conductivity of carbon nanotubes is about 3000 ~ 6000 (W /mK), so this study used different diameters carbon nanotubes doped within the epoxy resin to resolve the thermal conductivity problem of LED for P-N junction. By the Scanning Electron Microscope (SEM) and Transmission electron microscopy (TEM) observed results showed that the growth of material is carbon nanotubes not carbon fiber. By the SEM results showed that the carbon nanotubes uniformly dispersed within the epoxy resin.In this experiment, measuring the junction temperature using forward bias voltage can see that the Epoxy is about 120oC, epoxy doped diameter 50 nm CNT is about 107oC and Epoxy doped diameter 15 nm CNT is about 103oC.From above the data that carbon nanotubes doped in epoxy device that significantly reduces the junction temperature of high power LED is 17 oC. Such device improved the thermal dissipation of high power LED by up to 14%.
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Shih, Cheng-Hsin, and 石政欣. "Die Attach Glue Doped with Different AlN Particles for Improving Heat Dissipation of High Power LED." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/81479411170561976106.
Full textAbstract:
碩士崑山科技大學
光電工程研究所
99
In this paper, the researchers divided into two parts. Epoxy used in the current market rate is only the thermal conductivity of 0.8 Wm / K or so, has been unable to provide enough high-power LED thermal conductivity, if the device does not make good thermal conductivity of the LED chip accelerated aging, so in this paper Study of solid crystal plastic properties of the LED light and heat out of the front of the first part of the main market to sell the high thermal conductivity of the silver plastic; behind the second part, aluminum nitride doped with different body size (AlN) in LED solid crystal gel colloid. Part I: Use the market to sell three of the surface of the thermal conductivity of silver plastic, the thermal conductivity was 20 W/mK, 21 W/mK, 60 W/mK, found from three high thermal conductivity of silver Gum can improve the luminous efficiency and life improvement, but it will affect the ratio of doping silver push pull element value, silver and colloidal aggregation phenomena will affect the device lifetime. Part II: aluminum nitride, respectively, using different body size, crystal doped in LED solid-rubber, when the 150 nm doped aluminum nitride is 10 wt%, the operating current of 350 mA, the doped AlN Nano-powders of high power LED packaging than traditional high-power LED''s to enhance the flux by 3.3%; when the operating current of 1700 mA, the doped AlN nano powder of high power LED packaging than traditional high-power LED light power-up 31.6%. From the results of this study are two: First, in the light-emitting diode packaging applications, the doping of silver plastic LED components can effectively enhance the luminescence efficiency, but the high cost of silver, silver conductive resistance if the increase likely to cause further oxidation VF caused by component value increased. Second, in the light-emitting diode packaging applications, the doped AlN nano powder LED components, have shown improvement in flux. Especially doped 10 wt%, the sharpest increase light output flux.
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Lee, Chia-En, and 李佳恩. "Development of a novel chip structure for high-power light emitting diodes with heat-dissipation mirror substrates." Thesis, 2004. http://ndltd.ncl.edu.tw/handle/17642746804901643581.
Full textAbstract:
碩士國立中興大學
電機工程學系
92
High-efficiency light-emitting diodes (LEDs) are desired for many applications such as outdoor displays, automobile signals, and traffic indicators. It is well known that the AlGaInP LEDs lattice-matched GaAs substrates have the highest luminous efficiency in the yellow-to-red spectral region, and the GaN-based LEDs have the spectral region from green-to-blue. On the other hand, high power LEDs are usually driven on high current, the huge joule heating could contribute the early saturation trends of light output. Hence, in this thesis, the main purpose is to develop a novel chip structure for high-power light emitting diodes with heat dissipation mirror substrates. The LED device has not only the high reflective mirror but the high thermal dissipated metal substrate. Furthermore, the problem which was induced by metal dicing has also been avoided. The AlGaInP/mirror/Cu LEDs provide higher light output than original AlGaInP/GaAs LEDs due to the high reflective rate metal mirror. In the heat sink characteristic, It was found that the wavelength of the AlGaInP LED with Cu substrate exhibited only about 4 nm shift at 400 mA, corresponding to a ~40°C rising in the junction temperature. However, the junction temperature raised to 110 oC easily as the injection current at 400 mA for the AlGaInP/GaAs LED sample. This indicates that the device heating is more pronounced for the conventional AlGaInP LED with a GaAs substrate. Obviously, the metallic substrate provides a good thermal management. On the other hand, the GaN/mirror/Cu LEDs was developed by a combination of laser lift-off (LLO) and electroplating techniques. In particular, the I-V curves of the GaN/mirror/Cu and original GaN/sapphire LED samples are nearly the same. This suggests that the LLO and electroplating processes do not adversely affect the LED performance. The luminance intensity of the GaN/mirror/Cu LED is about 50% higher than that of the original GaN/sapphire sample. The output power of the GaN/mirror/Cu LED increases linearly with injection current up to 180 mA, while early saturation of the GaN/sapphire device occurs at 70 mA. These indicate that the joule heating is less pronounced for the GaN/mirror/Cu LED sample where the metallic substrate provides a good heat sink.
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Chen, Min-Yan, and 陳敏彥. "Die Bonding Epoxy Mixed with Carbon Group for Enhancement of Thermal Dissipation in High Power Light Emitting Diodes." Thesis, 2011. http://ndltd.ncl.edu.tw/handle/81264078802943175180.
Full textAbstract:
碩士崑山科技大學
光電工程研究所
99
LED is a kind of green products, compared with traditional light sources have the advantages of energy saving and long life, relatively high power LED, is a high density of thermal device, much of its thermal is even higher than the low-power LED. LED is electrically converted into light device, in conversion process, only 20% of the energy is converted into light, other energy converted into thermal and are stacked at the PN junction, excessive thermal will cause the LED performance degradation. In addition, epoxy its poor thermal conductivity, in this paper, using artificial diamonds and carbon nanotubes mixing with epoxy, increase thermal conductivity between LED chip and lead frame, improve the high-power LED thermal problems and increase its life. The results showed, there is no artificial diamonds or carbon nanotube mixed with epoxy of the LED junction temperature of 128℃ , when the artificial diamonds in the proportion of epoxy from 5% to 20%, also followed to reduce junction temperature, and 5% of the carbon nanotubes compared with, artificial diamond itself has thermal dissipation characteristics, and luminous flux is higher than 5% of the carbon nanotubes.
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MING, HUANG YU, and 黃羽銘. "A Novel High Power LED Chip on Board (COB) Bonding and Heat Dissipation Performance Study by Packaging Multi-Die in Series and Parallel." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/6475d8.
Full textAbstract:
碩士中華大學
機械工程學系碩士在職專班
101
This paper presents a novel high power LED COB (Chip On Board) bonding and heat dissipation performance study by packaging multi-die in series and parallel. The die separation distance and the operating voltage are the parameters to tradeoff. The temperatures on the top surface of LED and substrate of the die for the external power supply as 8 and 9 Volts are studied by using thermal couples. If one connects the COB dies in a 3 by 3 square matrix with 1.5mm separation distance and 8 (9) Volts power supply to turn on the LEDs; and the temperatures on the top surface of LED and substrate of the die can be respectively as 75.2 (90.5)℃ and 45.5 (56.5)℃. On the other hand, if the separation distance reduced to 1.0mm with the operating voltage of 8 (9) Volts, then the temperatures at the top and bottom of the LED surface would be increased to 75.7 (115.6) ℃ and 46.7 (59.8)℃, respectively.
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Sivaprasad, Sreenivasa J. "Control, Modulation and Testing of High-Power Pulse Width Modulated Converters." Thesis, 2013. http://etd.iisc.ac.in/handle/2005/3310.
Full textAbstract:
Experimental research on high-power converters, particularly in an academic environment, faces severe infrastructural constraints. Usually, power source and loads of required ratings are not available. Further, more importantly, the energy consumption is huge. One possibility is to establish an experimental research platform, comprising of a network of high-power converters, through which power is circulated and which draws only the losses from the mains.
This work deals with the establishment of a circulating power test set-up, comprising of two line-side PWM converters, inclusive of control and modulation methods for the two converters. Two types of circulating power test setups are developed. In the first setup, the converters are connected in parallel, on ac as well as dc sides, such that real and/or reactive power is circulated between them. In the second test setup, the dc buses of the converters are separated; hence, only reactive power circulation is possible. These setups are used to conduct heat-run tests with low energy expenditure on the PWM converters at various operating conditions up to power levels of 150 kVA. Further, these are used to validate analytically-evaluated thermal characteristics of high-power PWM converters. A safe thermal limit is derived for such converters in terms of apparent power (kVA) handled, power factor and switching frequency. The effects of voltage sag and of unequal current sharing between parallel IGBT modules on the safe thermal limit are studied.
While the power drawn by the circulating-power setup from the grid is much lower than the ratings of the individual converters, the harmonic injection into the mains by the setup could be significant since the harmonics drawn by both converters tend to add up. This thesis investigates carrier interleaving to improve the waveform quality of grid current, drawn by the circulating-power test setup. The study of carrier interleaving is quite general and covers various applications of parallel-connected converters such as unity power factor rectification, static reactive power compensation and grid-connected renewable energy systems.
In literature, carrier interleaving has been employed mainly for unity power factor rectifiers, sharing a common dc load equally. In such case, the fundamental components of the terminal voltages of the parallel converters are equal. However, when the power sharing between the two converters is unequal, or when power is circulated between the two converters, the terminal voltages of the two converters are not equal. A method to estimate rms grid current ripple, drawn by parallel-connected converters with equal and/or unequal terminal voltages, in a synchronous reference frame is presented. Further, the influence of carrier interleaving on the rms grid current ripple is studied. The optimum interleaving angle, which minimizes the rms grid current ripple under various applications, is investigated. This angle is found to be a function of modulation index of the converters in the equal terminal voltages case. In the unequal terminal voltages case, the optimum interleaving angle is shown to be a function of the average modulation index of the two parallel converters.
The effect of carrier interleaving is experimentally studied on the reactive power circulation setup at different values of kVA and different dc bus voltages. The grid current ripple is measured for different values of interleaving angle. It is found experimentally that the optimum interleaving angle reduces the rms grid current ripple by between 37% and 48%, as compared without interleaving, at various operating conditions.
Further, the reactive power circulation test set-up is used to evaluate and compare power conversion losses corresponding to different PWM techniques such as conventional space-vector PWM (CSVPWM), bus-clamping PWM (BCPWM) and advanced bus-clamping PWM methods for static reactive power compensator (STATCOM) application at high power levels. It is demonstrated theoretically as well as experimentally that an advanced bus-clamping PWM method, termed minimum switching loss PWM (MSLPWM), leads to significantly lower power conversion loss than CSVPWM and BCPWM techniques at a given average switching frequency.
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Sivaprasad, Sreenivasa J. "Control, Modulation and Testing of High-Power Pulse Width Modulated Converters." Thesis, 2013. http://etd.iisc.ernet.in/2005/3310.
Full textAbstract:
Experimental research on high-power converters, particularly in an academic environment, faces severe infrastructural constraints. Usually, power source and loads of required ratings are not available. Further, more importantly, the energy consumption is huge. One possibility is to establish an experimental research platform, comprising of a network of high-power converters, through which power is circulated and which draws only the losses from the mains.
This work deals with the establishment of a circulating power test set-up, comprising of two line-side PWM converters, inclusive of control and modulation methods for the two converters. Two types of circulating power test setups are developed. In the first setup, the converters are connected in parallel, on ac as well as dc sides, such that real and/or reactive power is circulated between them. In the second test setup, the dc buses of the converters are separated; hence, only reactive power circulation is possible. These setups are used to conduct heat-run tests with low energy expenditure on the PWM converters at various operating conditions up to power levels of 150 kVA. Further, these are used to validate analytically-evaluated thermal characteristics of high-power PWM converters. A safe thermal limit is derived for such converters in terms of apparent power (kVA) handled, power factor and switching frequency. The effects of voltage sag and of unequal current sharing between parallel IGBT modules on the safe thermal limit are studied.
While the power drawn by the circulating-power setup from the grid is much lower than the ratings of the individual converters, the harmonic injection into the mains by the setup could be significant since the harmonics drawn by both converters tend to add up. This thesis investigates carrier interleaving to improve the waveform quality of grid current, drawn by the circulating-power test setup. The study of carrier interleaving is quite general and covers various applications of parallel-connected converters such as unity power factor rectification, static reactive power compensation and grid-connected renewable energy systems.
In literature, carrier interleaving has been employed mainly for unity power factor rectifiers, sharing a common dc load equally. In such case, the fundamental components of the terminal voltages of the parallel converters are equal. However, when the power sharing between the two converters is unequal, or when power is circulated between the two converters, the terminal voltages of the two converters are not equal. A method to estimate rms grid current ripple, drawn by parallel-connected converters with equal and/or unequal terminal voltages, in a synchronous reference frame is presented. Further, the influence of carrier interleaving on the rms grid current ripple is studied. The optimum interleaving angle, which minimizes the rms grid current ripple under various applications, is investigated. This angle is found to be a function of modulation index of the converters in the equal terminal voltages case. In the unequal terminal voltages case, the optimum interleaving angle is shown to be a function of the average modulation index of the two parallel converters.
The effect of carrier interleaving is experimentally studied on the reactive power circulation setup at different values of kVA and different dc bus voltages. The grid current ripple is measured for different values of interleaving angle. It is found experimentally that the optimum interleaving angle reduces the rms grid current ripple by between 37% and 48%, as compared without interleaving, at various operating conditions.
Further, the reactive power circulation test set-up is used to evaluate and compare power conversion losses corresponding to different PWM techniques such as conventional space-vector PWM (CSVPWM), bus-clamping PWM (BCPWM) and advanced bus-clamping PWM methods for static reactive power compensator (STATCOM) application at high power levels. It is demonstrated theoretically as well as experimentally that an advanced bus-clamping PWM method, termed minimum switching loss PWM (MSLPWM), leads to significantly lower power conversion loss than CSVPWM and BCPWM techniques at a given average switching frequency.
49
Lalande, Émile. "Synthèse de couches optiques par co-dépôt pour les miroirs de LIGO." Thesis, 2021. http://hdl.handle.net/1866/25493.
Full textAbstract:
En 2015, le Laser Interferometer Gravitational-Wave Observatory (LIGO) a observé pour la
première fois des ondes gravitationnelles générées par la fusion de deux trous noirs. Cette
observation résulte de 40 ans d’efforts afin de réduire au minimum les sources de bruit qui
affectent l’interféromètre. À ce jour, la sensibilité de LIGO, dans son domaine de fréquence
le plus sensible, est limitée par la granularité de la lumière d’une part et, d’autre part,
par un phénomène de fluctuations thermiques résultat de la dissipation mécanique dans
les couches minces qui constituent ses miroirs, en particulier dans le matériau ayant un
haut indice de réfraction : l’oxyde de tantale. Une amélioration de la sensibilité permettrait
d’observer davantage d’événement, d’autres phénomènes gravitationnels, ainsi que des détails
importants permettant de mieux les comprendre.
Ce mémoire présente les résultats de nos recherches afin de diminuer le bruit causé
par la dissipation mécanique interne dans les couches à haut indice de réfraction. Pour
ce faire, des couches d’oxyde de tantale ont été dopées soit au zirconium ou à la fois au
zirconium et au titane, par co-dépôt. Des couches avec différentes quantités de dopant
ont été synthétisées par pulvérisation cathodique magnétron sur des substrats de silice
semblables à ceux de LIGO. Par la suite, la dissipation mécanique, l’épaisseur, la rugosité, la
composition, la densité surfacique, et la microstructure ont été caractérisées par suspension
nodale, ellipsométrie résolue spectralement, spectrométrie de rétrodiffusion de Rutherford
et la spectroscopie Raman. Il appert que le zirconium permet d’augmenter la température
de recuit avant la cristallisation, ce qui permet de diminuer plus amplement la dissipation
mécanique interne, mais ne change pas la dissipation à une température de recuit donnée.
Il a aussi été déterminé que la concentration de titane permettait de diminuer l’angle de
perte, peu importe la concentration de zirconium. Une combinaison des deux dopages
et un recuit à haute température permet ainsi de recuire par un facteur d’environ 1.5 la
dissipation mécanique interne. La différence de coefficient d’expansion thermique durant
les recuits à haute température induit cependant des problèmes de craquement des couches,
partiellement résolus par l’application d’une couche de recouvrement en silice.In 2015, the Laser Interferometer Gravitational-Wave Observatory (LIGO) observed for the first time gravitational waves generated by the merger of two black holes. This observation was the resut of 40 years of efforts to minimize the noise source which affect the the interferometer. To this date, the sensitivity of LIGO, in its most sensitive frequency domain, is limited by the granularity of the light on one hand, on the other, by a phenomenon of thermal fluctuations resulting from the mechanical dissipation in the thin film of the miroir, in particular in the high refractive index material: tantala. An improvement of the sensitivity would allow the measurement of more events, other gravitational phenomena and some details that would result in a better understanding. This master’s thesis presents results of our research to reduce the noise caused by internal mechanical dissipation in high refractive index layers. To do so, tantala layers were doped with either zirconium and titanium by co-deposition. Layers with different amounts of dopant were synthesized by magnetron sputtering on fused silica substrate similar to those of LIGO. Subsequently, mechanical dissipation, thickness, roughness, composition, areal density and microstructure were characterized by gentle nodal suspension, spectrally resolved ellipsometry, Rutherford backscattering spectroscopy, and Raman spectroscopy. It appears that zirconium allows the annealing temperature to be increased before crystallization which further decreases internal mechanical dissipation, but does not change dissipation at a given annealing temperature. It was also determined that the concentration of titanium reduced the loss angle regardless of the zirconium concentration. A combination of the two dopant and high annealing temperatures thus enables the internal mechanical dissipation to be lower by a factor of 1.5.The difference in thermal expansion coefficient during high temperature annealing, however, induces layer cracking problems, partially resolved by the application of a silica cap.