Дисертації: "Direct Current Converter (DC/DC)"

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Gowaid, Islam Azmy. "DC-DC converter designs for medium and high voltage direct current systems." Thesis, University of Strathclyde, 2017. http://digitool.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=27933.

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DC fault protection is one challenge impeding the development of multi-terminal dc grids. The absence of manufacturing and operational standards has led to many point-to-point HVDC links built at different voltage levels, which creates another challenge. Therefore, the issues of voltage matching and dc fault isolation in high voltage dc systems are undergoing extensive research and are the focus of this thesis. The modular multilevel design of dual active bridge (DAB) converters is analysed in light of state-of-the-art research in the field. The multilevel DAB structure is meant to serve medium and high voltage applications. The modular design facilitates scalability in terms of manufacturing and installation, and permits the generation of an output voltage with controllable dv/dt. The modular design is realized by connecting an auxiliary soft voltage clamping circuit across each semiconductor switch (for instance insulated gate bipolar transistor – IGBT) of the series switch arrays in the conventional two-level DAB design. With auxiliary active circuits, series connected IGBTs effectively become series connection of half-bridge submodules (cells) in each arm, resembling the modular multilevel converter (MMC) structure. For each half-bridge cell, capacitance for quasi-square wave (quasi two- level) operation is significantly smaller than typical capacitance used in MMCs. Also, no bulky arm inductors are needed. Consequently, the footprint, volume, weight and cost of cells are lower. Four switching sequences are proposed and analysed in terms of switching losses and operation aspects. A design method to size converter components is proposed and validated. Soft-switching characteristics of the analysed DAB are found comparable to the case of a two-level DAB at the same ratings and conditions. A family of designs derived from the proposed DAB design are studied in depth. Depending on the individual structure, they may offer further advantages in term of installed semiconductor power, energy storage, conduction losses, or footprint. A non-isolated dc-dc converter topology which offers more compact and efficient station design with respect to isolated DAB – yet without galvanic isolation – is studied for quasi two-level (trapezoidal) operation and compared to the isolated versions. In all the proposed isolated designs, active control of the dc-dc converter facilitates dc voltage regulation and near instant isolation of pole-to-pole and pole-to-ground dc faults within its protection zone. The same can be achieved for the considered non-isolated dc-dc converter topology with additional installed semiconductors. Simulation and experimental results are presented to substantiate the proposed concepts.

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Luth, Thomas. "DC/DC converters for high voltage direct current transmission." Thesis, Imperial College London, 2014. http://hdl.handle.net/10044/1/24466.

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High Voltage Direct Current (HVDC) transmission has to date mostly been used for point-to-point projects, with only a few select projects being designed from the outset to incorporate multiple terminals. Any future HVDC network is therefore likely to evolve out of this pool of HVDC connections. As technology improves, the voltage rating, at the point of commission, of the these connections increases. Interconnection therefore requires the DC equivalent of the transformer, to bridge the voltage levels and create a multi-terminal network. This thesis investigates new potential DC/DC converter topologies, which may be used for a range of HVDC applications. Simple interconnections of new and legacy HVDC links is unlikely to require a large voltage-step, but will be required to transfer a large amount of power. As the HVDC network develops it may become feasible for wind-farms and load-centres to directly connect to the DC network, rather than requiring new and dedicated links. Such a connection is called an HVDC tap and is typically rated at only a small fraction of the link's peak capacity (around 10\%). Such taps would connect a distribution voltage level to the HVDC network. DC/DC converters suitable for large-step ratios (>5:1) may find their application here. In this work DC/DC converters for both small and large step-ratios are investigated. Two approaches are taken to design such converters: first, an approach utilising existing converter topologies is investigated. As each project comes with a huge price-tag, their reliability is paramount. Naturally, technology that has already proven itself in the field can be modified more readily and quickly for deployment. Using two modular multilevel converters in a front-to-front arrangement has been found to work efficiently for large power transfers and low step-ratios. Such a system can be operated at higher than 50 Hz frequencies to reduce the volume of a number of passive components, making the set-up suitable for compact off-shore applications. This does however incur a significant penalty in losses reducing the overall converter efficiency. In the second approach DC/DC converter designs are presented, that are more experimental and would require significantly more development work before deployment. Such designs do not look to adapt existing converter topologies but rather are designed from scratch, purely for DC/DC applications. An evolution of the front-to-front arrangement is investigated in further detail. This circuit utilises medium frequency (>50 Hz) square current and voltage waveforms. The DC/DC step-ratio is achieved through a combination of the stacks of cells and a transformer. This split approach allows for high-step ratios to be achieved at similar system efficiencies as for the front-to-front arrangement. The topology has been found to be much more suitable for higher than 50 Hz operation from a losses perspective, allowing for a compact and efficient design.

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Jimenez, Carrizosa Miguel. "Hierarchical control scheme for multi-terminal high voltage direct current power networks." Thesis, Paris 11, 2015. http://www.theses.fr/2015PA112039/document.

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Cette thèse traite de la commande hiérarchique de réseaux à courant continu multi-terminaux à haute tension (MT-HVDC) intégrant des sources d'énergie renouvelables à grande échelle. Le schéma de contrôle proposé est composé de quatre ‘couches’ : le contrôle local où se trouvent les convertisseurs de puissance, avec une échelle de temps de l’ordre de la milliseconde ; le contrôle primaire qui est décentralisé et appliqué à plusieurs terminaux avec une échelle du temps de l’ordre de la seconde ; un niveau de commande où la communication est prise en compte et où l’approche de Modèle du Commande Prédictive (MPC) assure la planification de la tension et de la puissance à leur état d'équilibre, pour l'ensemble du système; enfin, le contrôleur de niveau supérieur, qui est principalement basé sur les techniques d'optimisation, où les aspects économiques sont pris en compte (il s’agit du réglage dit tertiaire).Au niveau des convertisseurs, un accent particulier est mis sur les convertisseurs bidirectionnels DC/DC. Dans cette thèse, trois topologies différentes sont étudiées en profondeur: deux phases Dual Active Bridge (DAB), trois phases DAB, et l’utilisation de la technologie Modular Multilevel converter (MMC) comme convertisseur DC/DC. Pour chaque topologie, une commande non-linéaire spécifique est discutée. D’autre part une nouvelle fonction pour le convertisseur DC/DC est étudiée. Il s’agit de son utilisation comme disjoncteur à courant continu (DC-CB). En ce qui concerne le contrôle primaire, qui permet de maintenir le niveau de tension continue dans le réseau, nous avons étudié trois philosophies de contrôle: celle de maître/esclave, celui du contrôle « voltage margin control » et celle de la commande du statisme (droop control). Enfin, nous avons choisi d'utiliser le droop control, entre autres, parce que la communication entre les nœuds n’est pas nécessaire. Concernant la commande secondaire, son principal objectif est de planifier le transfert de puissance entre les nœuds du réseau, qui fournissent la tension et la puissance de référence aux contrôleurs locaux et primaires, même lorsque des perturbations apparaissent. Dans cette partie, nous avons proposé une nouvelle approche pour résoudre les problèmes de flux de puissance (équations non-linéaires) basée sur le théorème du point fixe de l’application contractive. Ceci permet d'utiliser plus d'un slack bus, contrairement à l’approche classique basée sur la méthode de Newton-Raphson. Par ailleurs, le réglage secondaire joue un rôle très important dans les applications pratiques, en particulier lorsque les sources d'énergie renouvelables (variables dans le temps). Dans de tels cas, il est intéressant de considérer des dispositifs de stockage afin d'améliorer la stabilité de tout le système. Il est également possible d'envisager différents types de prévisions (météo, charge, ..) basées sur la gestion des réserves de stockage. Toutes ces caractéristiques ont suggéré l'utilisation d'une approche MPC. Dans ce contexte, plusieurs critères d'optimisation ont été considérés, en particulier la minimisation des pertes de transmission ou des congestions dans le réseau.La tâche principale de réglage tertiaire est de d'atteindre l'optimisation économique de l'ensemble du réseau. Dans cette thèse, nous avons pu maximiser le profit économique du système en agissant sur le marché réel, et en optimisant l'utilisation des périphériques de stockage. Dans le but de mettre en œuvre la philosophie de contrôle hiérarchique présentée dans cette thèse, nous avons construit un banc d'essai expérimental. Cette plate-forme dispose de quatre terminaux reliés entre eux par l'intermédiaire d'un réseau à courant continu, et connectés au réseau principal de courant alternatif. Ce réseau DC peut fonctionner à un maximum de 400 V, et avec une courant maximal de 15 A
This thesis focuses on the hierarchical control for a multi-terminal high voltage direct current (MT-HVDC) grid suitable for the integration of large scale renewable energy sources. The proposed control scheme is composed of 4 layers, from the low local control at the power converters in the time scale of units of ms; through distributed droop control (primary control) applied in several terminals in the scale of unit of seconds; and then to communication based Model Predictive Control (MPC) that assures the load flow and the steady state voltage/power plan for the whole system, manage large scale storage and include weather forecast (secondary control); finally reaching the higher level controller that is mostly based on optimization techniques, where economic aspects are considered in the same time as longer timespan weather forecast (tertiary control).Concerning the converters' level, special emphasis is placed on DC/DC bidirectional converters. In this thesis, three different topologies are studied in depth: two phases dual active bridge (DAB), the three phases DAB, and the use of the Modular Multilevel Converter (MMC) technology as DC/DC converter. For each topology a specific non-linear control is presented and discussed. In addition, the DC/DC converter can provide other important services as its use as a direct current circuit breaker (DC-CB). Several operation strategies are studied for these topologies used as DC-CB.With respect to primary control, which is the responsible to maintain the DC voltage control of the grid, we have studied several control philosophies: master/slave, voltage margin control and droop control. Finally we have chosen to use droop control, among other reasons, because the communication between nodes is not required. Relative to the secondary control, its main goal is to schedule power transfer between the network nodes providing voltage and power references to local and primary controllers, providing steady state response to disturbances and managing power reserves. In this part we have proposed a new approach to solve the power flow problem (non-linear equations) based on the contraction mapping theorem, which gives the possibility to use more than one bus for the power balance (slack bus) instead of the classic approach based on the Newton-Raphson method. Secondary control plays a very important role in practical applications, in particular when including time varying power sources, as renewable ones. In such cases, it is interesting to consider storage devices in order to improve the stability and the efficiency of the whole system. Due to the sample time of secondary control is on the order of minutes, it is also possible to consider different kinds of forecast (weather, load,..) and to achieve additional control objectives, based on managing storage reserves. All these characteristics encourage the use of a model predictive control (MPC) approach to design this task. In this context, several possibilities of optimization objective were considered, like to minimize transmission losses or to avoid power network congestions.The main task of tertiary control is to manage the load flow of the whole HVDC grid in order to achieve economical optimization. This control level provides power references to the secondary controller. In this thesis we were able to maximize the economic profit of the system by acting on the spot market, and by optimizing the use of storage devices. In this level it is again used the MPC approach.With the aim of implementing the hierarchical control philosophy explained in this thesis, we have built an experimental test bench. This platform has 4 terminals interconnected via a DC grid, and connected to the main AC grid through VSC power converters. This DC grid can work at a maximum of 400 V, and with a maximum allowed current of 15 A

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Toussaint, Pierre. "De la quasi-resonance introduite dans les convertisseurs, DC-DC de moyenne puissance : application à l'absorption sinusoïdale." Cachan, Ecole normale supérieure, 1994. http://www.theses.fr/1994DENS0013.

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Électronique de commutation pour l'essentiel, l'électronique de puissance met en œuvre des structures de convertisseurs ou la gestion des pertes par commutation pose problème. La commutation commandée lorsqu'elle est associée à des techniques d'aide a la commutation des interrupteurs, donne de bons résultats. Dans la gamme de puissance allant jusqu'a la dizaine de kilowatts, il existe une alternative à cette solution, que l'on désigne par le terme de quasi-résonance. L'étude présentée montre comment l'introduction de la commutation douce au sein de convertisseurs classiques permet d'obtenir d'aussi bonnes performances voire même meilleures, tout en simplifiant quelque peu la topologie des structures. Sa facilite de mise en œuvre est mise en évidence. La problématique du choix des interrupteurs est abordée. Un second problème pose par l'emploi de l'électronique de puissance et par la multiplication de convertisseurs, est la pollution du réseau auquel ils sont connectes. Afin de résorber cette pollution, des convertisseurs dits à absorption sinusoïdale (c. A. S. ) font l'objet d'études en tout points du globe. Une étude bibliographique leur est consacrée et une réalisation propre au laboratoire est détaillée. Ces convertisseurs fonctionnent en commutation commandée, aussi nous sommes nous attaches à développer des structures réalisant cette fonction de c. A. S. Tout en introduisant les techniques de commutation douce. Deux structures de flyback quasi-résonants, de 500 et 1300 w sont étudiées. Chacune consomme un courant sinusoïdal présentant un taux de distorsion inferieur à 10%. Une ébauche de modélisation de l'un de ces convertisseurs est également décrite

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Steckler, Pierre-Baptiste. "Contribution à la conversion AC/DC en Haute Tension." Thesis, Lyon, 2020. http://www.theses.fr/2020LYSEI075.

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Le courant alternatif (AC) se prêtant bien à la majorité des problématiques de production, de transport et de distribution de l'électricité, on comprend qu'il soit massivement utilisé. Cependant, depuis plus d'un siècle, les bénéfices du courant continu haute tension (HVDC, pour High Voltage Direct Current) pour les longues distances sont bien connus. Aux interfaces, des convertisseurs AC/DC sont requis, leur composition évoluant au fil des avancées technologiques. Après avoir présenté les spécificités du HVDC et les contraintes qu'il introduit sur les convertisseurs AC/DC, ce manuscrit se focalise sur trois topologies : Modular Multilevel Converter (MMC), Alternate Arm Converter (AAC) et Series Bridge Converter (SBC). Elles sont présentées, dimensionnées et analysées en détail, puis comparées de façon quantitative en utilisant des indicateurs de performance originaux. Il en ressort que le MMC et le SBC sont particulièrement intéressants. La méthode de commande conventionnelle du MMC est ensuite présentée et ses propriétés structurelles sont mises en évidence. Une première loi de commande originale est présentée, avec des performances similaires mais une complexité inférieure à l'état de l'art. La seconde est non linéaire, basée sur la théorie de la platitude différentielle, et permet un suivi de puissance très rapide tout en assurant la stabilité exponentielle globale du système. Ces lois de commande sont évaluées en simulation, avec un modèle moyen et un modèle détaillé intégrant 180 sous-modules par bras. La dernière partie concerne le SBC. Après l'avoir modélisé, des résultats concernant une analyse structurelle de la topologie sont présentés ainsi qu'une loi de commande originale. Le rôle fondamental du transformateur pour les convertisseurs à structure série comme le SBC est souligné. Enfin, les performances de la loi de commande proposée sont testées en simulation
As Alternating Current (AC) is well suited for most of the production, transmission, and distribution applications, its massive use is easy to understand. However, for over a century, the benefits of High Voltage Direct Current (HVDC) for long-distance energy transmission are well known. To connect both, AC/DC converters are mandatory, whose nature evolves with technological progress. After the problematic induced by HVDC on AC/DC converters is presented, this manuscript is focused on three topologies: Modular Multilevel Converter (MMC), Alternate Arm Converter (AAC) and Series Bridge Converter (SBC). They are presented, sized, analyzed thoroughly, and compared in quantitative terms, using original key performance indicators. It appears that MMC and SBC are particularly promising. The conventional control method of the MMC is then presented, and its structural properties are highlighted. A first original control law is presented, with similar performances but less complexity than the state-of-the-art. A second control law, non-linear and based on differential flatness theory, is introduced. It allows a very fast power tracking response while ensuring the global exponential stability of the system. These control laws are tested in simulation, using an average model and a detailed model with 180 sub-modules per arm. The last part is dedicated to the SBC. After a modeling step, some results regarding its structural analysis are presented, and an original control law is introduced. The essential role of the transformer for series converters like the SBC is highlighted. Finally, the performance of the proposed control law is assessed in simulation

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Yang, Gang. "Design of a High Efficiency High Power Density DC/DC Converter for Low Voltage Power Supply in Electric and Hybrid Vehicles." Thesis, Supélec, 2014. http://www.theses.fr/2014SUPL0011/document.

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Cette thèse traite de la conception d’un convertisseur DC / DC destiné aux véhicules électriques et hybrides (2,5 kW, 400V/14V, 250kHz). Dérivé de la topologie LLC à résonance, ce convertisseur bénéficie des nombreux avantages propres à cette structure particulière. C’est ainsi que le prototype réalisé présente un rendement très élevé, une densité de puissance très forte avec des perturbations EMI très réduites. La première partie de cette thèse est consacrée à l’analyse théorique du circuit LLC afin de dégager un modèle de conversion et une stratégie de contrôle adaptée à l’application visée. Afin de conserver un rendement important sur une large plage de charge, une structure basée sur la mise en parallèle de deux modules LLC est proposée. Une nouvelle stratégie de contrôle à deux boucles est également proposée pour équilibrer le courant entre les deux modules. La seconde partie de la thèse fait appel à la simulation et à l’expérimentation. Il s’agit de minimiser la masse et l’encombrement tout en maximisant le rendement. Un composant magnétique spécial est conçu puis dimensionné pour intégrer le transformateur et diverses inductances de résonance. Ce convertisseur met également en œuvre un système de redressement synchrone robuste avec une compensation de phase, un module de puissance avec une résistance thermique très faible et un système de refroidissement efficace par air. Le rendement maximal mesuré est 95%. Le rendement demeure supérieur à 94% sur une plage de puissance s’étalant de 500 W à 2 kW. La densité de puissance est 1W/cm3. La CEM du convertisseur est développée dans cette thèse
In this dissertation, a 2.5kW 400V/14V, 250kHz DC/DC converter prototype is developed targeted for electric vehicle/hybrid vehicle applications. Benefiting from numerous advantages brought by LLC resonant topology, this converter is able to perform high efficiency, high power density and low EMI. A first part of this dissertation is the theoretical analysis of LLC: topology analysis, electrical parameter calculation and control strategy. To arrange high output current, this thesis proposes parallel connected LLC structure with developed novel double loop control to realize an equal current distribution. The second part concerns on the system amelioration and efficiency improvement of developed LLC. A special transformer is dimensioned to integrate all magnetic components, and various types of power losses are quantified based on different realization modes and winding geometries to improve its efficiency. This converter also implements a robust synchronous rectification system with phase compensation, a power semiconductor module, and an air-cooling system. The power conversion performance of this prototype is presented and the developed prototype has a peak efficiency of 95% and efficiency is higher than 94% from 500W to 2kW, with a power density of 1W/cm3. The CEM analysis of this converter is also developed in this thesis

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Verdicchio, Andrea. "Nouvelle électrification en courant continu moyenne tension pour réseau ferroviaire." Thesis, Toulouse, INPT, 2019. http://www.theses.fr/2019INPT0093.

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Depuis le début du 20ème siècle, différents systèmes d’électrification ferroviaire en courantcontinu et en courant alternatif ont été développés en Europe. Les systèmes en courant alternatifmonophasé moyenne tension (25 kV-50 Hz ou 15 kV 16,7 Hz) permettent d’utiliser une caténairelégère de faible section de cuivre mais de par leur principe mettent en jeu de la puissancefluctuante et de la puissance réactive qu’il faut compenser par des dispositifs volumineux etcoûteux. Les systèmes d’électrification à courant continu (1,5kV ou 3kV) ne possèdent pas cesinconvénients mais en contrepartie, leur relativement faible niveau de tension implique lacirculation de courants élevés dans la caténaire ce qui s’oppose à toute augmentation de trafic carla section de cuivre ne peut pas être augmentée au-delà de 1000 mm2. Du point de vue dumatériel roulant, les locomotives alimentées en courant alternatif ont une chaine de conversiond’énergie électrique complexe et volumineuse (transformateur abaisseur, redresseur, filtre bassefréquence puis onduleur). En revanche, une chaine de conversion fonctionnant sous caténaire àcourant continu se réduit à un filtre d'entrée et à un onduleur de traction. Aujourd’hui, les progrèstechnologiques réalisés dans le domaine de l'électronique de puissance permettent d’envisager ledéveloppement de réseaux électriques à courant continu moyenne tension pour accompagner latransition énergétique en intégrant plus facilement des sources d’énergies renouvelables et deséléments de stockage d’énergie. Partant de ce constat, l’objectif de ce travail de thèse est deproposer un nouveau système d’électrification ferroviaire à courant continu moyenne tension,d’une part, dans le but de combiner les avantages des systèmes actuels d’électrification et d’autrepart, d’envisager à moyen terme la rénovation des lignes électrifiées à courant continu. Le premierchapitre de cette thèse présente un état de l’art des systèmes d’électrification ferroviaire existantset des chaines de traction associés. Le deuxième chapitre met en évidence l’intérêt d’uneélectrification à courant continu moyenne tension pour la traction ferroviaire. Une méthode decalcul, permettant de déterminer le niveau de tension continue pour un trafic donné, est proposée.Il est ainsi montré que le choix d’un niveau de tension à 9 kV permet d’obtenir des sections decaténaire et un espacement des sous-stations comparables au système 25kV-50 Hz. Dans sapremière partie, le troisième chapitre propose une stratégie permettant de faire évoluer le systèmed’électrification 1,5 kV existant en France vers un système 9 kV. En attendant que le parc d’enginsde traction soit adapté pour fonctionner sous une caténaire à 9 kV, il est possible de préparerl’évolution du système d’électrification en déployant une ligne de transport d’énergie électrique en9 kV (feeder) en parallèle de la caténaire 1,5 kV existante. Au terme de la période de transition, leniveau de tension 1,5 kV est complètement supprimé et la totalité de l’infrastructure ainsi que lesengins de traction fonctionnent alors sous 9 kV. La deuxième partie de ce chapitre est consacréeà l’étude d’une topologie associant des convertisseurs DC/DC isolés et permettant de remplir lafonction de transformateur électronique indispensable pour le renforcement de l’alimentation de lacaténaire 1,5 kV à partir du feeder 9 kV.Le quatrième chapitre présente la réalisation et les essaisd’un convertisseur DC/DC isolé d’une puissance de 300 kW utilisant des modules MOSFET SiC3,3 kV. Une conclusion générale et des perspectives concluent ce mémoire
Since the beginning of the 20th century, various DC and AC rail electrification systems have beendeveloped in Europe. Single-phase, medium-voltage AC systems (25 kV-50 Hz or 15 kV 16.7 Hz)allow the use of a light overhead-line of small copper cross-section but by their principle involvefluctuating power and reactive power that have to be compensated by large and expensivedevices. DC electrification systems (1.5kV or 3kV) do not have these disadvantages but in return,their relatively low voltage level involves the circulation of high currents in the overhead-line whichlimits any increase in traffic because the copper section cannot be increased beyond 1000 mm2.From a rolling stock point of view, AC powered locomotives have a complex and voluminousconversion chain (step-down transformer, rectifier, low-frequency filter and traction inverter). Onthe other hand, a conversion chain operating under direct current catenary is reduced to an inputfilter and a traction inverter. Today, the technological progress made in the field of powerelectronics makes it possible to envisage the development of medium voltage DC grids to supportthe energy transition by integrating more easily renewable energy sources and storage devices.On the basis of this observation, the aim of this thesis is to propose a new medium voltage DCrailway electrification system, on the one hand, with the aim of combining the advantages of thecurrent railway electrification systems and on the other hand, to consider in the medium term therenovation of lines electrified in DC. The first chapter of this thesis presents a state of the art ofexisting railway electrification systems and associated traction chains. The second chapterhighlights the interest of a medium voltage DC electrification for railway traction. A calculationmethod for determining the DC voltage level for a given traffic is proposed. Therefore, it is shownthat the choice of a voltage level at 9 kV makes it possible to obtain an overhead-line cross-section and a substation spacing comparable to the 25 kV-50 Hz system. In its first part, the thirdchapter proposes a strategy to upgrade the existing 1.5 kV French electrification system to a 9 kVsystem. Until the fleet of traction units is adapted to operate at 9 kV, it is possible to prepare theevolution of the electrification system by deploying a transmission line at 9 kV (feed-wire) inparallel with the existing 1.5 kV overhead-line. At the end of the transition period, the 1.5 kVvoltage level is completely removed and the entire infrastructure as well as the traction unitsoperate at 9 kV. The second part of this chapter is dedicated to the study of a topology, based onan association of isolated DC/DC converters, to fulfil the function of solid state transformer whichis essential for the power reinforcement of the 1.5 kV system from the 9 kV feed-wire. The fourthchapter presents the realization and tests of an isolated DC / DC converter with a power level of300 kW using 3.3 kV SiC MOSFET modules. A general conclusion and perspectives conclude thismanuscript

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Vidales, Luna Benjamin. "Architecture de convertisseur intégrant une détection de défauts d'arcs électriques appliquée au sources d'énergie continues d'origine photovoltaïques." Electronic Thesis or Diss., Université de Lorraine, 2021. http://www.theses.fr/2021LORR0040.

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Détection de défaut d'arcs intégrée dans un convertisseur intelligent contrôlé par FPGA pour les panneaux photovoltaïques. La mise au point de convertisseur intelligents intégrant des dispositifs de protection est une thématique que cherche à développer l'Institut Technologique de Morelia (Mexique) avec laquelle nous collaborons sur ce projet. L'objectif plus spécifique de ce travail repose sur la détection de défauts d'arc électrique en se basant sur le contrôle intelligent des onduleurs utilisés dans la gestion de l'énergie produite par des panneaux photovoltaïques. Depuis plusieurs années, le développement croissant des panneaux solaires photovoltaïques comme source d’énergie s’est imposé et la sécurité de ces dispositifs liée à la détection de défauts d’arcs électriques est devenu un enjeu majeur. L'approche que nous proposons dans ce travail est le développement d'une stratégie novatrice pour la surveillance et la prédiction de défaillance du réseau électrique constitué de panneaux solaires en présence de défauts d’arcs. Actuellement, la majorité des systèmes de détection comprennent des modules détecteurs disposés dans le circuit électrique à protéger dont la robustesse est loin d'être optimale. L'approche que nous proposons consiste à développer un dispositif de surveillance et de détection de défaut directement intégré dans l'onduleur intelligent. Le contrôle optimal de l'onduleur intelligent assurera une détection fiable de défaut d'arc sans déclenchement intempestif. Le dispositif comprendra également un système de coupure. La méthode de détection que nous privilégions sera basée sur l'analyse du courant et de la tension de ligne. Les algorithmes seront basés sur une analyse temps/fréquence des signatures courant et de tension suivie par une logique pertinente de décision de telle manière à minimiser le taux de fausses détections.Le noyau du convertisseur intelligent est constitué par un FPGA. Le parallélisme des traitements de données assurera le respect des contraintes temps réel. Dans le cadre du projet de thèse, la mise en œuvre, le test des algorithmes de détection et l’implémentation optimale afin de respecter les contraintes temps réel dans le FPGA sera mené dans le cadre d’une cotutelle de thèse entre l’institut technologique de Morelia et l’Université de Lorraine
In this research work, the development of a multilevel inverter for PV applications is presented. The PV inverter, has two stages one DC/DC converter and one DC/AC inverter, and is capable of generating an AC multilevel output of nine levels, it's a transformerless inverter and uses a reduced number of components compared to other topologies. The conception of a novel DC/DC converter is capable of generating two isolated DC voltage levels needed to feed the DC/AC stage. This DC/DC stage is developed in two variants, buck and boost, the _rst to perform the reduction of voltage when the DC bus is too high, and second to increase the voltage when the DC bus is too low to perform interconnection with the grid through the DC/AC inverter. This is achieved thanks to the parallel functioning of the developed topology, which make use of moderated duty cycles, that reduces the stress in the passive and switching components, reducing potential losses. The validation of the PV inverter is performed in simulation and experimental scenarios. In the other hand, the response of the inverter facing an arc fault in the DC bus is studied by performing a series of tests where the fault is generated in strategic points of the DC side, this is possible thanks to the design and construction of an arc fault generator based in the specifications of the UL1699B norm. During the tests is observed that with the apparition of an arc fault, there is a lost in the half-wave symmetry of the AC multilevel output voltage waveform, generating even harmonics which aren't present during normal operation, only when an arc fault is present in the DC system. The monitoring of even harmonics set the direction for developing the detection technique. Since the magnitude of even harmonics in the inverter is very low, the total even harmonic distortion is employed as a base for the detection technique presented in this thesis. The effectiveness of this method is verified with a series of tests performed with different loads

9

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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Mai, Yuan Yen. "Current-mode DC-DC buck converter with current-voltage feedforward control /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?ECED%202006%20MAI.

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11

Bandyopadhyay, Saurav. "45nm direct battery DC-DC converter for mobile applications." Thesis, Massachusetts Institute of Technology, 2010. http://hdl.handle.net/1721.1/60149.

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Thesis (S.M.)--Massachusetts Institute of Technology, Dept. of Electrical Engineering and Computer Science, 2010.
Includes bibliographical references (p. 65-66).
Portable devices use Lithium-ion batteries as the energy source due to their high energy density, long cycle life and low memory effects. With the aggressive downscaling of CMOS, it is becoming increasingly difficult to efficiently interface the low voltage, low power digital baseband and DSP of the mobile phone with the battery which maybe at voltages as high as 4.2V. This is efficiently done by a DC-DC converter which is a separate IC designed on an older generation process capable of handling high voltages. However, this requires an extra IC, thereby increasing the overall system cost. Here, a buck converter is demonstrated on a standard 45nm digital CMOS process which can be integrated with the 45nm digital core on the same die. This converter is capable of handling high battery voltages (2.8V to 4.2V) and delivers a regulated low voltage (0.5V to 1.1V) to the digital core. The converter can supply 20[mu]A to 100mA of load current. The peak efficiency of the converter is 87% for 73mW output at 4.2V supply and for the ultra low power levels, efficiency of 75% is obtained for a 20[mu]W load at 3V. Both pulse width modulation (PWM) and pulse frequency modulation (PFM) modes of control are used. A new digital pulse width modulator (DPWM) architecture is presented which provides 75% area savings over the conventional delay line and counter based architecture with comparable power consumption. The buck converter also requires Switched Capacitor (SC) DC-DC Converters to generate stacking regulators and regulator for the control circuitry. On the whole, the complete system integrates the Power Management Unit with the core for a single chip radio in 45nm.
by Saurav Bandyopadhyay.
S.M.

12

Chen, Christine M. Eng Massachusetts Institute of Technology. "Integrated DC-DC converter with ultra-low quiescent current." Thesis, Massachusetts Institute of Technology, 2013. http://hdl.handle.net/1721.1/84879.

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Thesis (M. Eng.)--Massachusetts Institute of Technology, Department of Electrical Engineering and Computer Science, 2013.
Cataloged from PDF version of thesis.
Includes bibliographical references (pages 93-94).
Based on the LTC3588, the design of a bandgap reference and a comparator for use in the control circuitry of DC-DC converter with an ultra-low quiescent current of 150nA is presented here. Not only will this thesis discuss the challenges encountered over the course of designing circuits to operate at such low current levels, but it will also provide proof of concept silicon evaluation data of modified LTC3588 chips demonstrating that such low current operation is viable.
by Christine Chen.
M.Eng.

13

Khopkar, Rahul Vijaykumar. "DC-DC converter current source fed naturally commutated brushless DC motor drive." Texas A&M University, 2003. http://hdl.handle.net/1969.1/1257.

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The aim of this work is to reduce the cost and size of a brushless dc motor (BLDC) drive as well as increase the reliability and ruggedness of that drive. Traditional BLDC drives use Voltage Source Inverters (VSI) that utilize hard switching, thereby generating switching losses and entail the use of large heatsinks. VSI needs a huge dc link capacitor that is inherently unreliable and is one of the most expensive components of a drive. Hence, a Current Source Inverter (CSI) is used to replace the hard switchings by natural turn-off, thereby eliminating the heatsinks as well as the large dc link capacitor. A controlled rectifier together with a large inductor act as the current source. The only disadvantage is the large value of the dc link inductor and the huge number of turns needed to achieve these values of the inductances lead to huge resistive losses. Therefore, it is shown that it is possible to replace the controlled rectifier and the large inductor with a suitable dc-dc converter based current source switching at high frequencies and a much smaller value of the dc link inductor. Switching at high frequencies makes it possible to reduce the value of the dc link inductor without increasing the current ripple. Hence, it is possible to have the advantages of using a CSI as well as reduce the value of the dc link inductor without a corresponding increase in the heat sink and snubber requirements.

14

Fan, Shixiong. "Current source DC/DC converter based multi-terminal DC wind energy conversion system." Thesis, University of Strathclyde, 2012. http://oleg.lib.strath.ac.uk:80/R/?func=dbin-jump-full&object_id=17007.

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Wind power energy conversion is growing rapidly in the world. There are two main wind farm types, namely ac grid-based and dc grid-based wind farms. The dc grid-based approach reduces the size and weight of the magnetic components and cables. In the dc system, the step-up dc/dc converter is the key component when interfacing the wind turbine to the ac grid, via its low/medium voltage generator. This thesis focuses on the control and design of a wind energy conversion system based on dc/dc current source converters. An optimized One-Power-Point method for maximum power tracking is proposed. It incorporates One-Power-Point control and Maximum Power Differential Voltage control to allow the wind turbine to extract more energy during rapid wind speed changes. A current output hard-switched full bridge converter and serial-parallel resonant converter with an intermediate high frequency transformer are investigated for interfacing wind turbines to a local dc grid. These converters are assessed and compared in terms of semiconductor stresses and losses. A new modified One-Power-Point control method is proposed for the dc/dc converter, which tracks the maximum power during wind speed changes. A design procedure for the serial-parallel resonant converter is presented, based on its characteristics specific to a wind energy conversion system (WECS). A current source dc/dc converter based multi-terminal dc WECS is presented, investigated, and simulated. A practical multi-terminal dc WECS verifies its feasibility and stability, using two dc current output wind turbine units. Furthermore, a coordinated de-loading control scheme for the current sourcing based WECS is proposed, to cater for ac grid demand changes. It combines pitch control, dc dumping chopper control, and dc/dc converter control, to safely and quickly establish de-loading control. Both simulation and experimental results verify the de-loading scheme.

15

Lau, Wai Keung. "Current-mode DC-DC buck converter with dynamic zero compensation /." View abstract or full-text, 2006. http://library.ust.hk/cgi/db/thesis.pl?ECED%202006%20LAU.

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zhou, hua. "MAGNETICS DESIGN FOR HIGH CURRENT LOW VOLTAGE DC/DC CONVERTER." Doctoral diss., University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3381.

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With the increasing demand for small and cost efficient DC/DC converters, the power converters are expected to operate with high efficiency. Magnetics components design is one of the biggest challenges in achieving the higher power density and higher efficiency due to the significant portion of magnetics components volume in the whole power system. At the same time, most of the experimental phenomena are related to the magnetics components. So, good magnetics components design is one of the key issues to implement low voltage high current DC/DC converter. Planar technology has many advantages. It has low profile construction, low leakage inductance and inter-winding capacitance, excellent repeatability of parasitic properties, cost efficiency, great reliability, and excellent thermal characteristics. On the other side, however, planar technology also has some disadvantages. Although it improves thermal performance, the planar format increases footprint area. The fact that windings can be placed closer in planar technology to reduce leakage inductance also often has an unwanted effect of increasing parasitic capacitances. In this dissertation, the planar magnetics designs for high current low voltage applications are thoroughly investigated and one CAD design methodology based on FEA numerical analysis is proposed. Because the frequency dependant parasitic parameters of magnetics components are included in the circuit model, the whole circuit analysis is more accurate. When it is implemented correctly, integrated magnetics technique can produce a significant reduction in the magnetic core content number and it can also result in cost efficient designs with less weight and smaller volume. These will increase the whole converter's power density and power efficiency. For high output current and low output voltage applications, half bridge in primary and current doublers in secondary are proved to be a very good solution. Based on this topology, four different integrated magnetics structures are analyzed and compared with each other. One unified model is introduced and implemented in the circuit analysis. A new integrated magnetics component core shape is proposed. All simulation and experimental results verify the integrated magnetics design. There are several new magnetics components applications shown in the dissertation. Active transient voltage compensator is a good solution to the challenging high slew rate load current transient requirement of VRM. The transformer works as an extra voltage source. During the transient periods, the transformer injects or absorbs the extra transient to or from the circuit. A peak current mode controlled integrated magnetics structure is proposed in the dissertation. Two transformers and two inductors are integrated in one core. It can force the two input capacitors of half bridge topology to have the same voltage potential and solve the voltage unbalance issue. The proposed integrated magnetics structure is simple compared with other methods implementing the current mode control to half bridge topology. Circuit analysis, simulation and experimental results verify the feasibility of these applications.
Ph.D.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering PhD

17

Prasantanakorn, Chanwit. "Current Sharing Method for DC-DC Transformers." Thesis, Virginia Tech, 2011. http://hdl.handle.net/10919/31112.

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An ever present trend in the power conversion industry is to get higher performance at a lower cost. In a computer server system, the front-end converter, supplying the load subsystems, is typically a multiple output power supply. The power supply unit is custom designed and its output voltages are fully regulated, so it is not very efficient or cost effective. Most of the load systems in this application are supplied by point-of-load converters (POLs). By leaving the output voltage regulation aspect to POLs, the front-end converter does not need to be a fully regulated, multiple output converter. It can be replaced by a dc-dc transformer (DCX), which is a semi-regulated or unregulated, single output dc-dc converter. A DCX can be made using a modular design to simplify expansion of the system capacity. To realize this concept, the DCX block must have a current sharing feature. The current sharing method for a resonant DCX is discussed in this work. To simplify the system architecture, the current sharing method is based on the droop method, which requires no communication between paralleled units. With this method, the current sharing error is inversely proportional to the droop voltage. In traditional DCX implementations, the droop voltage depends on the resistive voltage drops in the power stage, which is not sufficient to achieve the desired current sharing error. The resonant converter has the inherent characteristic that its conversion gain depends on the load current, so the virtual droop resistance can realized by the resonant tank and the droop voltage can be obtained without incurring conduction loss. An LLC resonant converter is investigated for its droop characteristic. The study shows the required droop voltage is achievable at very high switching frequency. To lower the switching frequency, a notch filter is introduced into the LLC resonant tank to increase the sensitivity of the conversion gain versus the operating frequency. The design of the multi-element resonant tank is discussed. Depending soly on the resonant tank, the droop characteristic is largely varied with the component tolerance in the resonant tank. The current sharing error becomes unacceptable. The active droop control is imposed to make the output regulation characteristic insensitive to the component tolerance. The proposed resonant DCX has simpler circuit structure than the fully regulated resonant converter. Finally simulation and experimental results are presented to verify this concept.
Master of Science

18

Van, Rhyn P. D. "High voltage DC-DC converter using a series stacked topology." Thesis, Link to the online version, 2006. http://hdl.handle.net/10019/1269.

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Choi, Byungcho. "Large signal transient analysis of duty ratio controlled DC-to-DC converter." Thesis, Virginia Tech, 1988. http://hdl.handle.net/10919/43966.

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The large-signal transient response of duty ratio controlled dc-to-dc converters is investigated using the phase-plane technique. The transition pattern of large-signal trajectories is provided in terms of the circuit parameter and operating conditions. Several transient trajectories of practical interest including start-up, step input voltage change and step-load change are analyzed. The effect of large-signal characteristics of the feedback controller on the transient trajectory is presented.
Master of Science

20

Saini, Dalvir K. "True-Average Current-Mode Control of DC-DC Power Converters: Analysis, Design, andCharacterization." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright1531776568809249.

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Zhang, Lu. "Development of LCL DC/DC transformer and fault current limiting LCL VSC converter for high power DC networks." Thesis, University of Aberdeen, 2014. http://digitool.abdn.ac.uk:80/webclient/DeliveryManager?pid=211240.

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In order to satisfy the huge demand energy transmission in future, the DC grid concept is proposed based on voltage sourced converter (VSC) HVDC and modular multilevel converter (MMC) HVDC technologies. It provides an attractive approach for long distance power transmission such as offshore renewable energy transmission in Europe. However, there are two main obstacles in the DC grid development. The first obstacle is the DC fault detection and selective isolation. Under severe fault condition, the DC grid is desired to isolate the healthy and faulty part which implies the whole grid system will operate normally during the fault. The second obstacle is the voltage stepping in DC grid system. The high power converter is desired to achieve high voltage stepping ratio yet must be cost-effective. In this thesis, an IGBT-based DC/DC converter employing an internal inductor-capacitor-inductor (LCL) passive circuit is presented to overcome above two obstacles. The proposed converter can achieve high voltage stepping without internal AC transformer implying smaller converter size and it is also designed to have reasonable efficiency in high power application. In addition, the converter has good response even under extreme fault conditions. The IGBT-based LCL DC/DC converter design procedure and performance under fault condition is investigated based on the theoretical studies initially. The converter is modelled on PSCAD platform under normal/fault operation and the simulation results are used for converter efficiency calculation and fault analysis. The advantages of IGBT-based LCL DC/DC converter are demonstrated by comparing with other two high power DC/DC converter topologies. A low power level prototype of LCL DC/DC converter is built following the design principle. The hardware results are used to verify the theoretical conclusions. The VSC converter is defenceless to DC faults in DC grid application. In order to overco The VSC converter is defenceless to DC faults in DC grid application. In order to overcome this major drawback, a fault tolerant VSC converter employing LCL passive circuit is studied in this thesis. The LCL VSC converter design principle is presented by analysing the converter equations. The converter model is developed on PSCAD platform under normal/fault operation. An advanced control method is designed based on developed MATLAB analytical model to improve the LCL VSC converter stability. The advantages of LCL VSC converter are presented by comparing with its performance with conventional L-VSC converter considering efficiency and fault response. A fault tolerant DC grid topology employing LCL VSCs and using low speed protection is also investigated in this thesis. The simple mechanical DC circuit breakers are used at DC bus bars and at connecting points of each DC cable. A comprehensive protection scenario including DC cable differential protection, DC bus bar protection and back up protection is employed to protect the whole DC grid against any probable DC faults. An accurate DC cable model is adopted for a four-terminal DC grid which is modelled on PSCAD platform. The advantage and feasibility of this method in DC fault protection is investigated based on the developed grid model.

22

Baglan, Fuat Onur. "Design Of An Educational Purpose Multifunctional Dc/dc Converter Board." Master's thesis, METU, 2008. http://etd.lib.metu.edu.tr/upload/2/12610103/index.pdf.

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In this thesis a multifunctional DC/DC converter board will be developed for utilization as an educational experiment set in the switched-mode power conversion laboratory of power electronic courses. The board has a generic power-pole structure allowing for easy configuration of various power converter topologies and includes buck, boost, buck-boost, flyback, and forward converter topologies. All the converters can be operated in the open-loop control mode with a switching frequency range of 30-100 kHz and a maximum output power of 20 W. Also the buck converter can be operated in voltage mode control and the buck-boost converter can be operated in peak-current-mode control for the purpose of demonstrating the closed loop control performance of DC/DC converters. The designed board allows for experimentation on the DC/DC converters to observe the macroscopic (steadystate/ dynamic, PWM cycle and low frequency) and microscopic (switching dynamic) behavior of the converters. In the experiments both such characteristics can be clearly observed such that students at basic learning level (involving only the macroscopic behavior), and students at advanced learning level (additionally involving the parasitic effects) can benefit from the experiments. The thesis reviews the switch mode conversion principles, gives the board design and proceeds with the experiments illustrating the capabilities of the experimental system.

23

Bills, David Marlin. "Soft Switching Multi-Resonant Forward Converter DC to DC Application for Communications Equipment." Master's thesis, University of Central Florida, 2007. http://digital.library.ucf.edu/cdm/ref/collection/ETD/id/3497.

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In the field of power electronics there is always a push to create smaller and more efficient power conversion systems. This push is driven by the industry that uses the power systems, and can be realized by new semiconductor devices or new techniques. This examination describes a novel technique for a small and highly efficient method of converting relatively high DC voltage to a very low voltage for use in the telecommunications industry. A modification to the standard Forward Resonant converter results in improvements in component stress, system efficiency, response time, and control circuitry. This examination describes background information needed to understand the concepts in DC to DC power systems, "soft-switching" topologies, and control methods for these systems. The examination introduces several topologies that are currently being used, and several types that have been previously analyzed, as a starting point for the detailed analysis of the proposed converter topology. A detailed analytical analysis is given of the proposed topology, including secondary effects, and component stresses. This analysis is compared to the results found from both Pspice simulation, and a working DC to DC converter. Finally, the topology is examined for potential improvements, and possible refinements to the model described.
M.S.E.E.
School of Electrical Engineering and Computer Science
Engineering and Computer Science
Electrical Engineering MSEE

24

Smith, Nathaniel R. "Characterization and Design of Voltage-Mode Controlled Full-Bridge DC/DC Converter with Current Limit." Wright State University / OhioLINK, 2018. http://rave.ohiolink.edu/etdc/view?acc_num=wright152721348332911.

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Witts, Joseph Harris James G. "Cal Poly SuPER system photovoltaic array universal DC-DC step down converter : a thesis /." [San Luis Obispo, Calif. : California Polytechnic State University], 2008. http://digitalcommons.calpoly.edu/theses/2/.

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Thesis (M.S.)--California Polytechnic State University, 2008.
"June 2008." "In partial fulfillment of the requirements for the degree of Master of Science in Electrical Engineering." "Presented to the faculty of California Polytechnic State University, San Luis Obispo." Major professor: James Harris, Ph.D. Includes bibliographical references (leaves 70-72). Also available online and on microfiche (2 sheets).

26

Thekkevalappil, Soniya Noormuhamed. "Hysteretic pulse width modulation with internally generated carrier for a boost dc-dc converter." [Gainesville, Fla.] : University of Florida, 2005. http://purl.fcla.edu/fcla/etd/UFE0013267.

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Deepak, G. "Integrated Magnetics Based DC-DC Converter Topologies For A DC Micro-Grid." Thesis, 2012. https://etd.iisc.ac.in/handle/2005/2310.

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In the present day, owing to the increasing number of electronic loads such as computer power supplies, Compact fluorescent lamps (CFL) and the increasing number of sources such as solar photovoltaics, fuel cells (DC sources), DC Micro-grids provide a more efficient solution compared to the AC counterpart in terms of the number of stages involved in conversion. Also, the ability to be readily buffered to storage elements is an advantage in a DC system. Apart from this, there are no issues of frequency stability, reactive power transfer and ac power losses. A DC micro-grid is effectively a multi-port dc-dc converter. The ports refer to the various sources and loads that are part of the micro-grid. Sources could be unidirectional (as in the case of PV, load) or bidirectional (as in the case of batteries). Interfacing a variety of ports and controlling power flow between these ports presents an interesting challenge. Commonly used topologies interface the various ports at the DC bus capacitor thereby making the DC bus capacitor bulky. Apart from this, the DC bus coupled topologies route power from one port to another via the central capacitor. This increases the number of stages in transferring power from one port to another. An alternative topology is to use the active bridge type converters where dynamic power flow equations are required to control inter-port power flow. But, as the number of stages increase, the computations get tedious.In this thesis, a novel topology is proposed that uses a UU type transformer core to interface all the power ports. This alleviates the problems faced in the DC bus coupled topologies. A PWM scheme to control simultaneous power flow from each of the ports is also proposed in this thesis. The PWM scheme enables the usage of simple constant frequency average current mode control to dynamically control power sharing ratio between the various ports delivering to loads. By means of the proposed PWM scheme and the control scheme, the drawbacks of the active bridge topologies are alleviated. Using the proposed topology and the PWM scheme, a prototype micro-grid system is developed for a system comprising of the utility grid, batteries, solar PVs and resistive loads. Yet another aspect of the thesis explores the concept of connecting multiple micro-grids in order to create a 'local power network'. A potential application for this could be in interconnecting residential buildings and routing power from one house to another in order to balance demand and supply among these houses. This is against the growing trend of using the utility grid to also sink power and subsequently route it to other houses connected to the grid. Unfortunately not all areas have access to the utility grid. Additionally, turning the grid bidirectional requires that a number of standards be met and policies be created. But, the standard for using a local network that only involves a unidirectional grid is fixed by the community that owns such a network. In a crude sense, this scenario can be compared to the existence of a local area network to transfer information among users of the network. In this thesis, a prototype local power network interconnecting two micro-grids has been implemented.

28

Deepak, G. "Integrated Magnetics Based DC-DC Converter Topologies For A DC Micro-Grid." Thesis, 2012. http://etd.iisc.ernet.in/handle/2005/2310.

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In the present day, owing to the increasing number of electronic loads such as computer power supplies, Compact fluorescent lamps (CFL) and the increasing number of sources such as solar photovoltaics, fuel cells (DC sources), DC Micro-grids provide a more efficient solution compared to the AC counterpart in terms of the number of stages involved in conversion. Also, the ability to be readily buffered to storage elements is an advantage in a DC system. Apart from this, there are no issues of frequency stability, reactive power transfer and ac power losses. A DC micro-grid is effectively a multi-port dc-dc converter. The ports refer to the various sources and loads that are part of the micro-grid. Sources could be unidirectional (as in the case of PV, load) or bidirectional (as in the case of batteries). Interfacing a variety of ports and controlling power flow between these ports presents an interesting challenge. Commonly used topologies interface the various ports at the DC bus capacitor thereby making the DC bus capacitor bulky. Apart from this, the DC bus coupled topologies route power from one port to another via the central capacitor. This increases the number of stages in transferring power from one port to another. An alternative topology is to use the active bridge type converters where dynamic power flow equations are required to control inter-port power flow. But, as the number of stages increase, the computations get tedious.In this thesis, a novel topology is proposed that uses a UU type transformer core to interface all the power ports. This alleviates the problems faced in the DC bus coupled topologies. A PWM scheme to control simultaneous power flow from each of the ports is also proposed in this thesis. The PWM scheme enables the usage of simple constant frequency average current mode control to dynamically control power sharing ratio between the various ports delivering to loads. By means of the proposed PWM scheme and the control scheme, the drawbacks of the active bridge topologies are alleviated. Using the proposed topology and the PWM scheme, a prototype micro-grid system is developed for a system comprising of the utility grid, batteries, solar PVs and resistive loads. Yet another aspect of the thesis explores the concept of connecting multiple micro-grids in order to create a 'local power network'. A potential application for this could be in interconnecting residential buildings and routing power from one house to another in order to balance demand and supply among these houses. This is against the growing trend of using the utility grid to also sink power and subsequently route it to other houses connected to the grid. Unfortunately not all areas have access to the utility grid. Additionally, turning the grid bidirectional requires that a number of standards be met and policies be created. But, the standard for using a local network that only involves a unidirectional grid is fixed by the community that owns such a network. In a crude sense, this scenario can be compared to the existence of a local area network to transfer information among users of the network. In this thesis, a prototype local power network interconnecting two micro-grids has been implemented.

29

Lakshminarasamma, N. "A New Family Of Soft Transition DC-DC Converters." Thesis, 2007. https://etd.iisc.ac.in/handle/2005/613.

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Switched mode power supplies (SMPS) have found wide spread acceptance in all power processing applications. The design demand is moving towards higher power densities. For reduction in size and weight, it is imperative to process the power at a higher switching frequency. High switching frequency requires soft switching techniques to reduce the switching losses. Several families of soft switching converters have emerged in the past two decades. Analysis and modelling methods have been proposed in relation with these topologies. Active clamp converters are the recently introduced soft switching topologies. Steady state analysis and model of these converters have been reported in literature. This thesis presents a uniﬁed equivalent circuit oriented model for the family of active clamp converters. Analytical expressions for DC conversion ratio in terms of pole current and throw voltage are derived for all the DC-DC converters with active clamp. The special feature is that, the conversion ratio exhibits a load dependent drop (IRd), where I is the pole current and Rd is the damping resistance. The damping resistance Rd is a mathematical artifact to represent the voltage loss on account of delay in the turn-on of the active switch. There is no energy loss associated with this load dependent drop. This is conveniently expressed as an appropriate lossless resistance in the equivalent circuit model. The proposed equivalent circuit models are valid for both steady-state and dynamic performance. A spread sheet based design is presented for the basic DC-DC converters with active clamp. A prototype design following the spreadsheet is made. The performance of the same is validated and veriﬁed by simulation and measurements. Steady state and dynamic results are presented. The stability criterion for the active clamp converters under current programming is investigated. The same is veriﬁed through simulation and validated on a current programmed active clamp converter prototype. The active clamp converters suﬀer from a few disadvantages: Higher VA ratings of switches, load dependent ZVS performance and increased component count. Several soft switching topologies have been reported in literature. Eﬃciency improvement and increase in switching frequency are obtained to diﬀerent degrees. This thesis proposes a new family of soft switching converters. This family of converters switch at constant frequency and maintains the advantages of traditional PWM converters. The proposed topology employs an auxiliary circuit to achieve soft switching. The auxiliary circuit consists of a dependent voltage source, an auxiliary switch, a series diode and a set of resonant elements (Inductor and capacitor). The switching transitions of both the active switch and the auxiliary switch are lossless. The novelty in the proposed circuit is the method of generating the dependent source required to enable zero current switching of the auxiliary switch. The dependent source is realized by a coupled winding in the energy storage inductor or tapped from the energy transfer transformer of non-isolated and isolated converters respectively. The proposed topology is applicable to most of the isolated and non-isolated DC-DC converters. The circuit equations governing the sub-intervals of the converter are expressed in terms of pole current and throw voltage. With such a deﬁnition, performance results and the design equations are identical for all types of DC-DC converters. Equivalent circuit models are obtained for the whole family of DC-DC converters. The proposed model is valid for steady state and dynamic performance. Analytical expressions of DC conversion ratio for all topologies, in terms of pole current and throw voltage are derived. The special feature is that, the conversion ratio exhibits a load dependent drop (IRd), where I is the pole current and Rd is the damping resistance. The damping resistance Rd is a mathematical artifact to represent the voltage loss on account of delay in the turn-on of the active switch. There is no energy loss associated with this load dependent drop. This is conveniently expressed as an appropriate lossless resistance in the equivalent circuit model. Design guidelines are established for the whole family of proposed converters; the same are validated through prototype converters.

30

Lakshminarasamma, N. "A New Family Of Soft Transition DC-DC Converters." Thesis, 2007. http://hdl.handle.net/2005/613.

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Switched mode power supplies (SMPS) have found wide spread acceptance in all power processing applications. The design demand is moving towards higher power densities. For reduction in size and weight, it is imperative to process the power at a higher switching frequency. High switching frequency requires soft switching techniques to reduce the switching losses. Several families of soft switching converters have emerged in the past two decades. Analysis and modelling methods have been proposed in relation with these topologies. Active clamp converters are the recently introduced soft switching topologies. Steady state analysis and model of these converters have been reported in literature. This thesis presents a uniﬁed equivalent circuit oriented model for the family of active clamp converters. Analytical expressions for DC conversion ratio in terms of pole current and throw voltage are derived for all the DC-DC converters with active clamp. The special feature is that, the conversion ratio exhibits a load dependent drop (IRd), where I is the pole current and Rd is the damping resistance. The damping resistance Rd is a mathematical artifact to represent the voltage loss on account of delay in the turn-on of the active switch. There is no energy loss associated with this load dependent drop. This is conveniently expressed as an appropriate lossless resistance in the equivalent circuit model. The proposed equivalent circuit models are valid for both steady-state and dynamic performance. A spread sheet based design is presented for the basic DC-DC converters with active clamp. A prototype design following the spreadsheet is made. The performance of the same is validated and veriﬁed by simulation and measurements. Steady state and dynamic results are presented. The stability criterion for the active clamp converters under current programming is investigated. The same is veriﬁed through simulation and validated on a current programmed active clamp converter prototype. The active clamp converters suﬀer from a few disadvantages: Higher VA ratings of switches, load dependent ZVS performance and increased component count. Several soft switching topologies have been reported in literature. Eﬃciency improvement and increase in switching frequency are obtained to diﬀerent degrees. This thesis proposes a new family of soft switching converters. This family of converters switch at constant frequency and maintains the advantages of traditional PWM converters. The proposed topology employs an auxiliary circuit to achieve soft switching. The auxiliary circuit consists of a dependent voltage source, an auxiliary switch, a series diode and a set of resonant elements (Inductor and capacitor). The switching transitions of both the active switch and the auxiliary switch are lossless. The novelty in the proposed circuit is the method of generating the dependent source required to enable zero current switching of the auxiliary switch. The dependent source is realized by a coupled winding in the energy storage inductor or tapped from the energy transfer transformer of non-isolated and isolated converters respectively. The proposed topology is applicable to most of the isolated and non-isolated DC-DC converters. The circuit equations governing the sub-intervals of the converter are expressed in terms of pole current and throw voltage. With such a deﬁnition, performance results and the design equations are identical for all types of DC-DC converters. Equivalent circuit models are obtained for the whole family of DC-DC converters. The proposed model is valid for steady state and dynamic performance. Analytical expressions of DC conversion ratio for all topologies, in terms of pole current and throw voltage are derived. The special feature is that, the conversion ratio exhibits a load dependent drop (IRd), where I is the pole current and Rd is the damping resistance. The damping resistance Rd is a mathematical artifact to represent the voltage loss on account of delay in the turn-on of the active switch. There is no energy loss associated with this load dependent drop. This is conveniently expressed as an appropriate lossless resistance in the equivalent circuit model. Design guidelines are established for the whole family of proposed converters; the same are validated through prototype converters.

31

Swaminathan, B. "Resonant Transition Topologies For Push-Pull And Half-Bridge DC-DC Converters." Thesis, 2004. https://etd.iisc.ac.in/handle/2005/317.

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Switched mode power supplies (SMPS) are being extensively used in most power conversion processes. The analysis, design and modeling processes of hard-switched converters are mature, where the switching frequency was limited to a few 10's of kHz. The present direction of evolution m SMPS is towards higher efficiency and higher power density. These twin objectives demand high switching frequency and low overall losses. Soft switching results in practically zero switching losses and extends the switching frequency to 100's of kHz and beyond. This thesis presents novel variants of push-pull and half-bridge DC-DC converters with soft switching properties. The proposed topology uses two additional switches and two diodes. The additional switches introduce freewheeling intervals m the circuit and enable loss-less switching. Switch stress, control and small signal model are similar to hard-switched PWM converter. Synchronous rectifiers are used in the ZVS push-pull converter to achieve high efficiency. It is interesting to see that the drives for the synchronous rectifier device are practically the same as the additional switches. The contributions made in this thesis are 1) Idealized analysis and design methodology for the proposed converters. 2) Validation of the design through circuit simulation as well as prototypes - a 300kHz, 200W push-pull converter and a 300kHz, 640W half-bridge converter. 3) Closed loop control design for desired bandwidth and accuracy Verification of loop gain through network analyzer instrumental for the same The loop gain bandwidth achieved is about 30kHz for the push-pull converter and 20kHz for half-bridge converter. An appendix has been devoted to explain the use of network analyzer. Characterization of coil, transformer and capacitor are explained in detail. Measurement techniques for measuring the small signal parameters of power supply are also explained in the appendix.

32

Swaminathan, B. "Resonant Transition Topologies For Push-Pull And Half-Bridge DC-DC Converters." Thesis, 2004. http://hdl.handle.net/2005/317.

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Switched mode power supplies (SMPS) are being extensively used in most power conversion processes. The analysis, design and modeling processes of hard-switched converters are mature, where the switching frequency was limited to a few 10's of kHz. The present direction of evolution m SMPS is towards higher efficiency and higher power density. These twin objectives demand high switching frequency and low overall losses. Soft switching results in practically zero switching losses and extends the switching frequency to 100's of kHz and beyond. This thesis presents novel variants of push-pull and half-bridge DC-DC converters with soft switching properties. The proposed topology uses two additional switches and two diodes. The additional switches introduce freewheeling intervals m the circuit and enable loss-less switching. Switch stress, control and small signal model are similar to hard-switched PWM converter. Synchronous rectifiers are used in the ZVS push-pull converter to achieve high efficiency. It is interesting to see that the drives for the synchronous rectifier device are practically the same as the additional switches. The contributions made in this thesis are 1) Idealized analysis and design methodology for the proposed converters. 2) Validation of the design through circuit simulation as well as prototypes - a 300kHz, 200W push-pull converter and a 300kHz, 640W half-bridge converter. 3) Closed loop control design for desired bandwidth and accuracy Verification of loop gain through network analyzer instrumental for the same The loop gain bandwidth achieved is about 30kHz for the push-pull converter and 20kHz for half-bridge converter. An appendix has been devoted to explain the use of network analyzer. Characterization of coil, transformer and capacitor are explained in detail. Measurement techniques for measuring the small signal parameters of power supply are also explained in the appendix.

33

Γιαννόπουλος, Σπυρίδων. "Έλεγχος τριφασικού ac/dc αντιστροφέα από την πλευρά του δικτύου για απευθείας στήριξη της αέργου ισχύος με τοπική παραγωγή αιολικού συστήματος". Thesis, 2014. http://hdl.handle.net/10889/8095.

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Οι συνεχώς αυξανόμενες ενεργειακές απαιτήσεις της σύγχρονης κοινωνίας σε συνδυασμό με τις ραγδαίες κλιματικές αλλαγές μας οδηγούν στην ανάγκη παραγωγής ηλεκτρικής ενέργειας με όσο το δυνατό πιο οικονομικό και φιλικό προς το περιβάλλον τρόπο. Έτσι, οι Ανανεώσιμες Πηγές Ενέργειας αποκτούν ολοένα και μεγαλύτερο μερίδιο στην παραγωγή ηλεκτρικής ενέργειας, αλλάζοντας συνεχώς τον παγκόσμιο ενεργειακό χάρτη. Τα αιολικά συστήματα, τα οποία αξιοποιούν την κινητική ενέργεια του ανέμου, είναι ένα είδος ΑΠΕ. Στην παρούσα εργασία μελετάμε ένα αιολικό σύστημα, το οποίο αποτελείται από μία ανεμογεννήτρια μεταβλητών στροφών που χρησιμοποιεί μία σύγχρονη μηχανή μόνιμου μαγνήτη, έναν μετατροπέα πηγής τάσης, ένα R-L φίλτρο στην πλευρά του δικτύου και μία γραμμή μεταφοράς μικρού μήκους. Η αυξημένη αξιοπιστία και απόδοση της ΣΜΜΜ την καθιστούν ιδιαίτερα ελκυστική λύση για τα αιολικά συστήματα. Στην εργασία αυτή προσομοιώνουμε σε περιβάλλον Matlab/Simulink το σύστημα που περιγράψαμε παραπάνω. Εφαρμόζοντας τις κατάλληλες τεχνικές ελέγχου από την πλευρά της μηχανής προσπαθούμε να πετύχουμε μέγιστη απομάστευση ισχύος από τον άνεμο, ενώ στην πλευρά του δικτύου προσπαθούμε μέσω άμεσου ελέγχου ροής ισχύος να πετύχουμε μοναδιαίο συντελεστή ισχύος με ταυτόχρονη ρύθμιση της τάσης της dc διασύνδεσης. Στη συνέχεια, μέσω ενός πρόσθετου ελέγχου προσπαθούμε να κρατήσουμε την τάση στην έξοδο του φίλτρου σταθερή, κατά τη διάρκεια πτώσης της τάσης του δικτύου. Τέλος, παραθέτουμε τα αποτελέσματα της προσομοίωσης μαζί με έναν σύντομο σχολιασμό και τα συμπεράσματα.
The continuously increasing energy requirements of modern society combined with the rapid climate changes lead us to the need to produce electrical energy in a more economic and environmentally friendly way. Thus, the Renewable Energy Sources gain an increasing share of electrical energy production, constantly changing the global energy map. Wind power systems, which utilize the kinetic energy of the wind, are a kind of RES. In this thesis we study a wind power system, which comprises a variable speed wind turbine, which uses a permanent magnet synchronous machine, a voltage source converter, an R-L filter in the grid side and a short transmission line. The increased reliability and performance of PMSG make it particularly attractive solution for wind power systems. In this thesis we simulate in Matlab/Simulink environment the system described above. Applying appropriate control techniques on the machine side we try to achieve maximum power harvesting from the wind, while on the grid side we try through direct power flow control to achieve unit power factor with simultaneous control of the dc link voltage. Then, using an additional control we try to keep constant the voltage at the end of the R-L filter during a grid voltage drop. Finally, we present the simulation results along with a brief commentary and the conclusions.

34

劉育廷. "Digital Current Mode DC-DC Converter." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/91935440386309142214.

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35

Shyam, V. "Development Of An Application Specific Parallel Processing Real-Time System For MTDC System Control." Thesis, 1996. https://etd.iisc.ac.in/handle/2005/1755.

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36

Shyam, V. "Development Of An Application Specific Parallel Processing Real-Time System For MTDC System Control." Thesis, 1996. http://etd.iisc.ernet.in/handle/2005/1755.

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37

Yu-Hui, Sung, and 宋玉惠. "Implementation of 8MHz Current-Mode Buck DC-DC Converter." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/17297645957351678156.

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碩士
國立交通大學
電機學院IC設計產業專班
95
This thesis proposes a new DC-DC switching converter with a high switching frequency for reducing the size of the output filter. Owing to the high switching frequency, the on-chip output filter in DC-DC switching converter is possible in the future. Thus, how to develop a DC-DC switching converter with high switching frequency is important in today’s technology. Therefore, a compact solution is needed to effectively reduce the footprint area of the power management module in system-on-chip (SoC) systems. Furthermore, a high performance power converter module is also needed to provide a regulated and stable supply voltage to the SoC systems because the operation voltage of the SoC systems is too low to have a good signal-to-noise ratio. For providing a high performance supply voltage, the current-mode technique is utilized to get better line and load regulations. However, the current sensing accuracy and response time is seriously affected by the high switching frequency. A high accuracy and small response time current sensor is also proposed in this thesis. In thesis, we implement an 8 MHz current-mode buck DC-DC converter with good line and load regulations. The chip is implemented by tsmc 2P4M 0.35u CMOS process. The range of the operation voltage is from 2.6V to 3.3V. The load regulation and line regulation are 0.88uV/mA and 4.67mV/V. The chip features smaller output filter elements and fast response, which makes it suitable for power management in the portable devices.

38

Chen, Chien-cheng, and 陳建成. "A High Efficiency Current Mode Control DC-DC Buck Converter." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/07494232505610402844.

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碩士
國立中央大學
電機工程研究所
99
In this changing rapidly era of electronic technology, the major demands of portable electronics are short, thin, and full functionalities. These sub-circuits of the portable electronics, which use batteries for power sources, need a stable supply voltage generating by power converters. These power converters must have low power consumption and high efficiency to extend the service time of portable electronics. Thus, a high efficiency current mode buck converter is presented in this thesis. The proposed buck converter uses current-mode controlling mechanism to accelerate the transient response during the transient period. It senses the current variation of the output inductor. Therefore, it achieves low operating current and high efficiency by removing the V-to-I converting circuit. This buck converter has better performance in the specification of efficiency comparing with traditional buck converter with current-mode controlling. This current-mode buck converter is fabricated with TSMC 0.35um 3.3 V CMOS process. In the proposed buck converter, the operation voltage is form 3.8 V to 5.5 V, the output voltage is 3.3 V, the output current is from 0.05 A to 1 A, and the highest efficiency is 97.4 %. The line regulation and load regulation are 17.5 mV/V and 1.15 mV/A, respectively. The chip area is 2.46 mm2.

39

Chin-HongChen and 陳津宏. "Average-Current-Mode Non-inverting Buck-Boost DC-DC Converter." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/77890091296649204660.

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碩士
國立成功大學
電機工程學系碩博士班
98
With the increasing use of electrical portable devices, an efficient power management solution is needed to extend battery life. Generally, basic switching regulators (e.g., buck, boost) are not capable of using the entire battery output characteristics effectively (e.g., 2.7–4.2 V for Li-ion) to provide a fixed output voltage (e.g., 3.3V). In this work, an average-current-mode non-inverting buck-boost dc-dc converter is introduced, which can use the full-range output voltage of Li-ion battery with the advantages of high power efficiency, faster transient response, and excellent noise immunity. The die area of this chip is 1.9x1.7 , which is fabricated by using Taiwan Semiconductor Manufacturing Company (TSMC) 0.35μm 2P4M 5V mixed-signal polycide process. The converter output is set to 3.3V, and can supply up to 300 mA load current. Its input votlage can range from 2.5V to 5V.

40

Chen, Chien-Nan, and 陳建男. "A Current-Mode CMOS DC-DC Switching Converter with on-chip Current-Sensor." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/85539169363340614963.

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碩士
國立臺灣科技大學
電子工程系
95
A current-mode CMOS DC–DC converter with integrated power switches and on-chip current sensor for feedback control is presented in this paper. The sensed inductor current, combined with the internal ramp signal, can be used for current-mode DC–DC converter feedback control. In addition, no external components and no extra I/O pins are required for the current-mode controller. The DC–DC converter has been fabricated with the TSMC CMOS digital process. The simulation results show that this converter with on-chip current sensor can operate in 1.5 MHz with supply voltage varied from 4.5 to 3.5 V, which is suitable for single-cell lithium-ion battery supply applications, with a off-chip capacitor and a off-chip inductor. The maximum power efficiency is 94.3% for load current varied from 50 to 500 mA. The supply voltage range of the converter can be adjusted from 3.5V to 4.5V. For line regulation simulation, the output voltage is always stabilized at the preset value with a maximum output ripple of . For load regulation simulation by varying the output current from 0.5A heavy load to 0.1A light load, the maximum output ripple is merely . The combined regulation has been simulated with both line regulation and load regulation, and the maximum output ripple is . There are three supply voltages of 3.8V, 3.6V, and 4V simulated along with process variation to generate a maximum output ripple of . For temperature variation of ~ , the maximum output ripple is . All above results confirm the excellence of the proposed circuit compared with the commercialized chips. The chip size of the proposed circuit is which is merely 53.66% of those of its predecessors. With such tiny size, the proposed converter is excellent for low cost but high efficiency portable applications to greatly enhance the product competitiveness.

41

Kuo-ChunWu and 吳國鈞. "Average-Current-Mode Buck-Boost DC-DC Converter with Full-Wave Current Sensor." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/12640023247879599750.

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碩士
國立成功大學
電機工程學系碩博士班
101
Due to the growth of consumer electronics market, there are more and more studies in energy saving to prolong service life of electronic products. Because the output voltage of batteries decreases with time (e.g., Li-ion: 2.7–4.2 V), it may be higher or lower than the required supply voltage (e.g., 3.3V). To use the entire battery output voltage range, a non-inverting buck-boost dc-dc converter is a good choice. In this work, an average-current-mode non-inverting buck-boost dc-dc converter with the advantages of high power efficiency, faster transient response, and excellent noise immunity is introduced. Furthermore, a novel current sensing scheme, which can reduce noise and then improve system stability, is proposed. The die area of this chip is 2.3x1.86 , which is fabricated by using Taiwan Semiconductor Manufacturing Company (TSMC) 0.35μm 2P4M 5V mixed-signal polycide process. The converter output is regulated to 3.3V, when the loading current is 50 mA to 300 mA and the input voltage is 2.5V to 5V.

42

Chen, Jian-Hao, and 陳建豪. "Constant-Frequency Hysteresis-Current-Controlled DC-DC Converter with Active-Current-Sensing Techniques." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/3j6734.

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43

Chiang, Ta-Jen, and 江大任. "Realization of a ZVS Current-Fed Boost Converter for Bi-directional DC/DC Converter." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/95229697296824328865.

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碩士
中原大學
電機工程研究所
105
Thesis is to improve the boost conversion characteristics of the bidirectional full-bridge DC / DC converters and to maintain the excellent behavior of the phase-shifted buck conversion. Quasi-resonant full-bridge current-fed method is adopted to achieve the boost energy conversion with constant-off time control, while the switches are commutated at zero-voltage-switching (ZVS) to enhance the conversion efficiency. In this study, a full-bridge bidirectional DC / DC converter with output power of 1 kW is implemented to verify the proposed method, where the low-side DC bus is 48V and the high-side DC bus 380V. Finally, the phase-shifted buck conversion is also tested in the same circuit topology. The experimental results confirm that the maximum conversion efficiency of the boost mode is 90%, while that of the buck mode is 88%.

44

Hsu, Hsin-Ju, and 許昕茹. "Automatic Layout Synthesis Tool for DC-DC Current-Mode Buck Converter." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/64617872141924593723.

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碩士
國立中央大學
電機工程學系
105
In our days, lots of electronic product are made of analog/mixed-signal (AMS) intergrated circuits (ICs), such as portable devices, medical equipment, communication product and automobile electronics etc. Nowadays, with the growing demands for portable devices, Time-to-Market cycle still keeps shrinking. Electronic design automation (EDA) tools are the keys to speed up the device process. There are many existing EDA tools for digital circuits on the market. However, the EDA tools for AMS circuits are still not popular. Because analog circuits are often sensitive to small signals response, their layouts are often manually designed by experienced designers. Therefore, AMS circuit design has become the bottleneck in SoC design flow. In order to increase the circuit performance and shorten design process, we perpose an automatic layout synthesis tool for DC-DC current-mode control buck converters in the thesis. This synthesis tool is able to generate the final layout of the target circuit automatically from given specification. The design environment is developed with C++ and Tcl/Tk programming language. The required layout can be generated in Laker automatically and pass the DRC/LVS verification. The post-layout simulation results also satisfy the required specification.

45

Wu, Shing-Lih, and 吳行立. "The Research of DC to DC Converter for Current Sharing Control." Thesis, 2005. http://ndltd.ncl.edu.tw/handle/45090815512461023180.

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碩士
逢甲大學
電機工程所
93
Abstract The advance of VLSI brings a new challenge for transfering high power to microprocessors. As Intel predicted, the microprocessors will operate at low voltage, high current and high slew rate, with the continuous increase in the speed and transistor number within the chips. To increase transistor number and processor speed ，the improvement of current demands and transition speed is much more desirable. In order to reduce power consumption, the supply voltage of the microprocessors have been decreased. For future microprocessors with low voltage and high current, can not only increae computation speed and performance, but can also increase slew rate of output current. In order to improve the efficiency of synchronous buck converter, multiphase interleave synchronous buck converter is widely used. In this paper, a multiphase interleave technology ,which can used in synchronous buck converter, is proposed.

46

Hsuan-ChingSu and 蘇軒瑨. "High Step-Up Current-Fed DC-DC Converter with Coupled Inductor." Thesis, 2013. http://ndltd.ncl.edu.tw/handle/08113321242325984541.

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碩士
國立成功大學
電機工程學系碩博士班
101
In this thesis, a novel high step-up current-fed DC-DC converter with coupled inductor has been proposed. This converter has advantages of simple structure and high efficiency. In addition, output-voltage stacking technique has been adopted, so that the voltage stress on each power device can be reduced. Besides, the converter is a current-fed type which can reduce input current ripple. By the means that two capacitors have been charged simultaneously and been discharged in series, it can achieve the purpose of high voltage conversion ratio. The converter can get high voltage ratio about 16 times by operating duty cycle above 0.5. The highest conversion efficiency of the proposed converter is 96.06%. Moreover, the conversion efficiencies are above 95% from light load to full load. First, different types of high step-up converters are introduced. Second, the analysis of operating principle of the proposed converter is performed. Then, design the power devices’ parameters of the main circuit. Finally, a prototype circuit with 24 V input voltage, 400 V output voltage and 200 W output power is implemented to verify the performance of the proposed converter.

47

Zone-ChingLee and 李宗慶. "Implementation of a Current-Fed High Step-Up DC-DC Converter." Thesis, 2010. http://ndltd.ncl.edu.tw/handle/73581722044410605304.

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碩士
國立成功大學
電機工程學系碩博士班
98
High step-up techniques have been explored and developed for boost converter applications. However, many of the converters have the problem of high pulsating input currents from the power source, which often is a disturbance on the DC output of a renewable power source, like fuel cells or solar PV cells. Concerned is the significant impact on fuel cell diffusion layer or the output power of solar PV cells. For this reason, high step-up of current-fed configuration converter is considered more suitable for renewable source generation system, especially for the fuel cells. Based on SEPIC converter and cascade topology, this thesis proposes a current-fed high voltage step-up DC-DC converter. The first inductor of the proposed converter is operated in continuous conduction mode, which has lower pulsating input current and thus reduced current ripple. The reduced current ripple can minimize the input electrolytic capacitor needed and extend its life-time as well as reliability. The second inductor employed in the proposed circuit is a coupled inductor to achieve much higher voltage conversion ratio and avoid operation at extreme duty ratio via a proper turn ratio. In addition to, the voltage spike on the main switch can being clamped, the leakage inductance of the coupled inductor is designed to be recycled to output load. Therefore, with reduced voltage stress on the power switch, its power-rating and on resistance can be lower to further decrease both switching and conduction losses. Moreover, synchronous rectifier is applied into the front-end of the proposed converter to further decrease conduction losses. The operation principles and analyses of the steady-state and voltage stress on each semiconductor device are presented in this thesis. Feasibility and effectiveness of the proposed circuit are verified via computer simulations and practical experiments.

48

Liu, Ti-Ti, and 劉玓玓. "A Current Domain Boost DC-DC Converter for LED Driver Applications." Thesis, 2007. http://ndltd.ncl.edu.tw/handle/44033038272983008687.

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碩士
國立交通大學
電機與控制工程系所
96
In the past, the backlight module for liquid crystal displays (LCD) consisted mainly of cold cathode fluorescent lamp (CCFL). However, with the greatly improving technology of light emitting diode (LED) process, the benefit for LED backlight is more and more obviously such as high color saturation, longer product life and none hydrargyrum. Thus, people are trying to replace CCFL to RGB LED to reach the high quality images in displays targeted for market. Two most popular approaches for LED driver implementation are an inductor-less charge pump converter and an inductor-based converter. Although the cost and EMI problem of a charge pump is low, the load ability and efficiency is poor compared to those of a switching regulator. In the application of high brightness LED driver, the high power characteristics are needed, since the number of LEDs for backlight implementation is above hundreds. The highly efficient voltage regulators are needed for energy transform, because of low power consumption in converters. Moreover, owing to driving a large number of LEDs in one controller, the cost of the system is reduced. This thesis presents a current domain DC-DC boost converter for LED application with 12V input voltage and 48V output voltage. The boost voltage regulator utilizes a pulse width modulation (PWM) current programmed control method, which transfers the control signal in current domain to improve the transient response. The disadvantage of this method is big static error. The supply voltage of the controller is in the range from 2.5V to 3.6V. The best efficiency of the converter is 92% at 300mA load current. This converter design is simulated and fabricated in UMC 0.35�慆 embedded high voltage 3.3V/18V CMOS technology.

49

Pai-YiWang and 王派益. "A Current-Mode DC-DC Buck Converter with Variable-Frequency Controller." Thesis, 2009. http://ndltd.ncl.edu.tw/handle/53741969966548917400.

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碩士
國立成功大學
電機工程學系碩博士班
98
A current-mode buck converter with integrated analog variable-frequency controller (VFC) is implemented in this thesis. With the highly growing market of the portable devices, a compact, fast, low cost and high efficiency regulator is needed in power management solutions. Design of the regulator with small inductor can significantly reduce the PCB size and cost; and it is inherently faster than general solutions due to higher filtering bandwidth. But small inductor makes higher output voltage ripple, thus the design of switching frequency is limited by the rated output voltage ripple; faster switching frequency though effectively reduces the output voltage ripple without increasing the output capacitance, but introduces more frequency-dependent power loss such as switching loss and dead-time loss into regulator. By adapting VFC, which can be easily integrated in a chip without complex control circuts, the efficiency can be optimized under rated output voltage ripple with small inductor value. Furthermore, the proposed current-mode regulator provides an improvement of the current sensor, reducing the controller power loss while maintaining sensing accuracy, and eliminating the sensed noise, providing better sensed signal quality to the feedback loop, significantly promoting the performance of current-mode switching regulator. This current-mode buck regulator is fabricated with TSMC 0.35um 3.3/5V Mixed-Signal CMOS process. The total chip area is about 1.06 x 0.995 mm2. Verification results show that power saving at least 5mW and 20mW during light load and heavy load individually.

50

Li, Kuang-Chieh, and 李光傑. "Research on Current Detection Improvement Method for DC-DC Buck Converter." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/cwjzm6.

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碩士
國立臺灣海洋大學
電機工程學系
105
In recent years, the application of electronic devices is widely spread. DC-DC converters are increasingly important due to their use for power control of the electronic devices. Because current detection significantly affects the quality control of DC-DC buck converters, this thesis is aimed to research an improvement strategy on current detection to overcome the disadvantages of the commonly used current detection scheme. The thesis focuses on finding a current detection scheme, named inductor DC resistance sensing , for the purposes of low cost and low power conversion loss, as well as its strength and weakness as compared to the resistor sensing method. The inductor DC resistance sensing method uses a series resister-capacitor circuit connected with an inductor (parasitic DC resistance) in parallel, which doesn’t alter the converter’s structure and affect little power conversion efficiency, thus is suitable for current detection of low power loss DC-DC converters. Experimental results show that the resistor sensing method is better if system needs precise current detection, available space is large enough and power loss is endurable. Otherwise, the inductor DC resistance sensing method is the better choice for current detection.

Дисертації з теми "Direct Current Converter (DC/DC)"

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