• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 31
  • 21
  • 8
  • 6
  • 6
  • 4
  • 3
  • 2
  • 1
  • 1
  • 1
  • 1
  • 1
  • Tagged with
  • 98
  • 46
  • 28
  • 24
  • 22
  • 22
  • 20
  • 19
  • 16
  • 14
  • 12
  • 11
  • 10
  • 10
  • 10
  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
61

Utveckling av en universell laddare / Development of a universal charger

Sahlberg, Mikael January 2007 (has links)
<p>Syftet med examensarbetet har varit att undersöka möjligheterna att utveckla, producera och lansera en ny universell laddare. Målet har varit att kunna ladda så många modeller av så många produkter som möjligt, vilket innefattar mobiltelefoner, kameror, datorer och MP3-spelare etc. Arbetet skulle leda fram till ett förslag på produkt.</p><p>Genom att undersöka befintliga patent och produkter, har marknaden granskats och slutsatsen är att det finns en uppsjö av universella laddare på marknaden. Dock finns det få produkter som inger säkerhet, möjliggör multipel laddning och som är stationära. Dessa egenskaper blev grundstenar i den kravspecifikation som utarbetades. Genom en teknisk analys och kundundersökning sammanställdes ytterligare viktiga parametrar.</p><p>Resultatet blev en stationär produkt som kan ladda både en bärbar dator och flera mindre elektroniska produkter. Genom att använda en metod som i rapporten betecknas tappteknik kan rätt laddningsförhållande garanteras. Med hjälp av en mikroprocessor och produktspecifika tappar eller ändadaptrar kan laddning av i princip alla sorters produkter och modeller ske.</p><p>Arbetet har även innefattat konstruktion, CAD och prototypframtagning.</p> / <p>The purpose with this thesis work has been to investigate the possibilities to develop, manufacture and introduce a new universal charger. The aim has been to be able to charge as many models of as many different products as possible, including cell phones, cameras, laptops, MP3-players etc. The work would lead to a product proposal.</p><p>By an examination of existing patents and products, has the market been reviewed. The conclusion is that there already are big amount of universal chargers in the international market. Yet there are only a few products that inspire safety, have a multiple charging function and which are for stationary use. Those properties became fundamentals in the specification. With a technical analyse and a customary review were more parameters included.</p><p>The result is a stationary product that can be used to charge both a laptop and several smaller electronic products. By using a method that is called tip technology can the right charging conditions be guaranteed. With a micro processor and with tips which are specific for each product can mostly all sorts of products and models be charged.</p><p>The work has also included mechanical design, CAD and the build of a prototype.</p>
62

A New perspective in rural electrification in DC voltage: an experience in the State of Piauà / Uma Nova perspectiva de eletrificaÃÃo rural em corrente contÃnua: uma experiÃncia no Estado do PiauÃ

Emanoel Augusto Paulo Soares 21 November 2011 (has links)
O presente trabalho apresenta os estudos, especificaÃÃes, instalaÃÃo e operaÃÃo de um sistema fotovoltaico com a finalidade de fornecer energia elÃtrica a uma escola pÃblica, localizada em uma Ãrea isolada do sul do Estado do PiauÃ. O sistema foi proposto e seu protÃtipo constituÃdo por painel fotovoltaico, banco de baterias, carregador do banco de bateria e conversor CC/CC elevador, que alimenta as cargas em corrente contÃnua, projetado para uma autonomia de trÃs dias, mesmo em condiÃÃes mÃnimas de radiaÃÃo solar. A energia solar capturada pelo painel solar à armazenada em um banco de baterias estacionÃrias do tipo chumbo-Ãcido. O carregador de baterias trabalhando no ponto de mÃxima potÃncia (MPP) do painel à responsÃvel pelo carregamento deste banco. A carga à suprida pelo conversor CC/CC elevador de alto ganho (24 Vdc para 311 Vdc). O projeto completo do sistema à apresentado ao longo deste trabalho, bem como sÃo apresentados os principais resultados experimentais do protÃtipo mostrado e instalado em campo. / This work presents the studies, specifications, installation and operation of a photovoltaic system in order to provide electricity to a public school located in an isolated area of the southern state of PiauÃ. The system was proposed and its prototype constituted by photovoltaic panel, battery bank, charger from the battery bank and converter DC / DC elevator, that feed the chargers in direct current designed for a range of three days, even in minimum solar radiation. The solar energy captured by solar panel is stored in a stationary batteries, lead acid type. The battery charger working at maximum power point (MPP) of the panel is responsible for load bank. The load is supplied by the DC / DC converter lift high gain (24 Vdc to 311 Vdc). The complete design system and its control are presented throughout this work, as well as presented the main results of the experimental prototype shown and installed in the field.
63

Utveckling av en universell laddare / Development of a universal charger

Sahlberg, Mikael January 2007 (has links)
Syftet med examensarbetet har varit att undersöka möjligheterna att utveckla, producera och lansera en ny universell laddare. Målet har varit att kunna ladda så många modeller av så många produkter som möjligt, vilket innefattar mobiltelefoner, kameror, datorer och MP3-spelare etc. Arbetet skulle leda fram till ett förslag på produkt. Genom att undersöka befintliga patent och produkter, har marknaden granskats och slutsatsen är att det finns en uppsjö av universella laddare på marknaden. Dock finns det få produkter som inger säkerhet, möjliggör multipel laddning och som är stationära. Dessa egenskaper blev grundstenar i den kravspecifikation som utarbetades. Genom en teknisk analys och kundundersökning sammanställdes ytterligare viktiga parametrar. Resultatet blev en stationär produkt som kan ladda både en bärbar dator och flera mindre elektroniska produkter. Genom att använda en metod som i rapporten betecknas tappteknik kan rätt laddningsförhållande garanteras. Med hjälp av en mikroprocessor och produktspecifika tappar eller ändadaptrar kan laddning av i princip alla sorters produkter och modeller ske. Arbetet har även innefattat konstruktion, CAD och prototypframtagning. / The purpose with this thesis work has been to investigate the possibilities to develop, manufacture and introduce a new universal charger. The aim has been to be able to charge as many models of as many different products as possible, including cell phones, cameras, laptops, MP3-players etc. The work would lead to a product proposal. By an examination of existing patents and products, has the market been reviewed. The conclusion is that there already are big amount of universal chargers in the international market. Yet there are only a few products that inspire safety, have a multiple charging function and which are for stationary use. Those properties became fundamentals in the specification. With a technical analyse and a customary review were more parameters included. The result is a stationary product that can be used to charge both a laptop and several smaller electronic products. By using a method that is called tip technology can the right charging conditions be guaranteed. With a micro processor and with tips which are specific for each product can mostly all sorts of products and models be charged. The work has also included mechanical design, CAD and the build of a prototype.
64

Analysis and Control Aspects of a PMSynRel Drive in a Hybrid Electric Vehicle Application

Zhao, Shuang January 2013 (has links)
This thesis deals withmodeling and control of an electric drive equipped with a permanentmagnet assisted synchronous reluctance (PMSynRel) machine for a plug-in hybrid electric vehicle application. In the first part of the thesis, a special use of the PMSynRel machine in consideration, known as an integrated charger concept, is investigated. The integrated charger feature allows using the PMSynRel machine as a part of the vehicle’s on-board charging system when charging the battery from the grid. A finite-element based analysis is performed providing important insights into the machine operation during the charging process. Dynamic models are developed that facilitate the controller development and the estimation of the efficiency during charging. In the second part of the thesis, position sensorless control of the PMSynRel drive when applied in an automotive application is considered and analyzed thoroughly. First, a fundamental-excitation based rotor-position estimation technique is investigated. The study shows that the impact of current dynamics on the resulting torque dynamics has to be considered in some very demanding applications. Second, focus is put on signalinjection based sensorless control methods. Impacts of nonlinearities, such as magnetic saturation, cross-saturation and inductance spatial harmonics, on sensorless control performance are investigated and methods to improve the sensorless control quality are summarized and presented. An approach to determine the feasible region for operating sensorless at low-speeds without directly measuring the differential inductances is proposed. For the PMSynRel drive in consideration, the achievable maximum torque is limited when operating sensorless following the maximum-torque-per-ampere (MTPA) current reference trajectory at low-speeds. An optimization approach is therefore proposed which extends the output torque when operating sensorless while still maintaining a relatively high efficiency. To initialize the sensorless control correctly from standstill, the impact of the saturated magnetic bridges in the rotor is also investigated. Finally, torsional drive-train oscillations and active damping schemes are considered. An off-vehicle setup for implementing and evaluating different active damping schemes is proposed. Of particular interest for sensorless operation in automotive applications, the impact of slow speed estimation on the possibility to achieve good active damping control is investigated and a design approach that allows the implementation of an active damping scheme using estimated speed is suggested. / <p>QC 20140114</p>
65

Wide Input Common-mode Range Fully Integrated Low-dropout Voltage Regulators

January 2016 (has links)
abstract: The modern era of consumer electronics is dominated by compact, portable, affordable smartphones and wearable computing devices. Power management integrated circuits (PMICs) play a crucial role in on-chip power management, extending battery life and efficiency of integrated analog, radio-frequency (RF), and mixed-signal cores. Low-dropout (LDO) regulators are commonly used to provide clean supply for low voltage integrated circuits, where point-of-load regulation is important. In System-On-Chip (SoC) applications, digital circuits can change their mode of operation regularly at a very high speed, imposing various load transient conditions for the regulator. These quick changes of load create a glitch in LDO output voltage, which hamper performance of the digital circuits unfavorably. For an LDO designer, minimizing output voltage variation and speeding up voltage glitch settling is an important task. The presented research introduces two fully integrated LDO voltage regulators for SoC applications. N-type Metal-Oxide-Semiconductor (NMOS) power transistor based operation achieves high bandwidth owing to the source follower configuration of the regulation loop. A low input impedance and high output impedance error amplifier ensures wide regulation loop bandwidth and high gain. Current-reused dynamic biasing technique has been employed to increase slew-rate at the gate of power transistor during full-load variations, by a factor of two. Three design variations for a 1-1.8 V, 50 mA NMOS LDO voltage regulator have been implemented in a 180 nm Mixed-mode/RF process. The whole LDO core consumes 0.130 mA of nominal quiescent ground current at 50 mA load and occupies 0.21 mm x mm. LDO has a dropout voltage of 200 mV and is able to recover in 30 ns from a 65 mV of undershoot for 0-50 pF of on-chip load capacitance. / Dissertation/Thesis / Masters Thesis Electrical Engineering 2016
66

Conception d'un équilibreur de charge de batterie à base du réseau de micro-convertisseurs / Battery charge balancer based on network of micro-converters. Design and development for improvement of energy efficiency and reliability

Phung, Thanh Hai 20 December 2013 (has links)
Depuis ces années, le développement de systèmes de stockage d'énergie pour la mobilité électrique avec davantage d'autonomie de durabilité est au cœur des contraintes de développement des véhicules électriques ou hybrides entraînant une émergence de l'utilisation des systèmes de management ainsi que des circuits d'équilibrage. Les travaux de thèse portent sur la conception et la réalisation d'une nouvelle structure d'équilibrage à base du réseau de micro-convertisseurs (RµC) utilisant les matrices de connections ainsi que les stratégies de commande appropriées. L'objectif principal est de concevoir un équilibreur actif forcé de haute performance, intégrable à base de technologies d'aujourd'hui et avec une stratégie de contrôle simple à mettre en œuvre. Le mémoire de thèse se structure en quatre chapitres : approche du RµC versus l'équilibrage des batteries, conception de la structure et des stratégies d'équilibrage à base du RµC, conception et dimensionnement du système de contrôle intégrée, version intégrée de l'équilibreur-perspectives. Les premiers prototypes de l'équilibreur utilisant des composants discrets ont été mis en place afin de valider notre structure ainsi que les solutions de contrôle proposées. La réalisation des versions intégrées en se basant sur l'utilisation les technologies disponible au sein du laboratoire ouvre un avenir promettant pour les systèmes de management de batterie. / In recent years, the development of energy storage systems for electric mobility with greater autonomy of sustainability is at the heart of development constraints of electric or hybrid vehicles resulting in the emergence of the use of management systems as well as balancing circuits. The thesis focuses on the design and implementation of a new balancing based network structure of micro-inverters (RμC) using matrices connections and appropriate control strategies. The main objective is to design an active balancer forced high performance integrated based technologies of today and a simple control strategy to implement. The thesis is structured in four chapters: RμC approach versus balancing batteries, structural design and balancing based strategies RμC, design and simulation of control system built, integrated version of the balancer - perspectives. The first prototypes of the balancer using discrete components were developed to validate our structure and control solutions proposed. The realization of integrated based on using the technologies available in the laboratory versions opens a promising future for battery management systems.
67

Transmission dynamique d'énergie par induction : application au véhicule électrique / Dynamic inductive power transfer applied to electric vehicles

Gori, Paul-Antoine 23 October 2019 (has links)
L’autonomie limitée du véhicule électrique est le premier frein au développement du marché de l’électrique. La charge inductive dynamique répond à ce problème, en offrant de charger son véhicule en roulant. La principale difficulté est de gérer les variations importantes du couplage magnétique lors du déplacement du véhicule, et ce pendant le transfert de puissance. Une précédente thèse dans l’équipe de recherche sur un prototype de 3 kW avait abouti au concept de recopie de tension, qui stabilise la tension en sortie du coupleur malgré la variation de couplage, et facilite notablement la conception du convertisseur DC/DC faisant interface avec la batterie. La thèse présentée ici porte sur l’adaptation du système pour fonctionner de 20 kW à 30 kW. Cette montée en puissance n’est pas évidente, du fait des importantes contraintes électriques sur les bobines du coupleur (1,4 kV sur le système de 3 kW), et du champ rayonné limité par des références normatives. Tout d’abord, nous proposons une nouvelle commande du circuit résonnant, qui permet de modifier le dimensionnement pour aboutir à des contraintes électriques plus faibles tout en conservant la recopie de tension. Ensuite, une forme de bobine en huit est étudiée pour aider à réduire le champ rayonné. Enfin, une démarche de dimensionnement est établie pour la partie électrique du système, ainsi que pour le coupleur magnétique, alliant modèle analytique et simulations à éléments finis et réduisant considérablement les temps de simulations. Les résultats de l’évaluation des performances du système dimensionné pour la haute puissance sont prometteurs. / The limited electric-vehicle distance range is the main reason hindering the development of the electric transportation market. Dynamic inductive charging solves this problem, offering the possibility to charge while driving. The main issue consists in handling wide magnetic coupling variations when the vehicle is moving, while charging. A previous thesis in the research team on a 3-kW prototype led to the concept of voltage copying, which stabilises the coupler output voltage despite the varying coupling, making it easier to design the DC/DC converter linking the coupler to the battery. The hereby thesis deals with adapting this system to transfer from 20 kW to 30 kW. Raising the power is no small matter, due to the high electrical constraints on the coupled coils (1.4 kV on the 3-kW system), and the radiated field, limited by standardised thresholds. Firstly, a new control of the resonating circuit is proposed, allowing to change the system design to get lower electrical constraints and maintaining voltage copying properties. Then, an eight-shape coil was investigated in order to reduce the radiated field. Finally, a design method was conceived for the electrical part of the system, as well as the magnetic coupler, using jointly analytical models and finite element simulations to reduce simulation times. Results of the evaluated performance for such a high-power system are quite promising.
68

Vývoj ovládacího programového prostředí pro autonomní fotovoltaický systém / Development control programme for autonomous fotovoltaic system

Janáč, Stanislav January 2009 (has links)
The project considers realization system, which allows us to test six different operation modes on lifetime of accumulators. The system will be connected to computer, that will perform measurement of current and voltage and switch betwen charge and discharge modes. The measured values will be recorded in certain time intervals to computer memory. After some time these measured data will be analised and the most optimal operational mode will be set.
69

Vývoj fukčních bloků pro autonomní fotovoltaický systém / Functional blocks for the development of autonomous photovoltaic system

Ovesný, Karel January 2011 (has links)
The project considers realization system, which will allow us to test six different operation modes on lifetime accumulators. The system will link to computer, which will execute measurement current and tension and switch betwencharging and discharging modes. The measured values will record in someone time intervals in to computer memory. After someone time will analise these measured valuer and will provide optional operation mode.
70

Décharge à Barrières Diélectriques à pression atmosphérique pour la charge bipolaire d’aérosol / Atmospheric pressure dielectric barrier discharge for aerosol bipolar charging

Mathon, Rémi 17 December 2015 (has links)
La mesure de distribution de taille d’un aérosol (particules solides ou liquides en suspension dans un gaz) par analyse de mobilité électrique nécessite de neutraliser l’aérosol. La neutralisation consiste à conférer une distribution de charge centrée sur zéro obtenue par la diffusion sur l’aérosol d’ions bipolaires. Nous avons démontré la faisabilité d’un chargeur bipolaire post-Décharge à Barrières Diélectriques (DBD) pour remplacer les neutraliseurs radioactifs, généralement utilisées pour la production d’ions bipolaires et soumis à des contraintes législatives. La caractérisation électrique des DBD en géométrie « fil-fil » selon la distance inter-électrodes, la tension et le débit a permis demettre en évidence trois types d’auto-organisations des filaments selon la tension et d’évaluer lecourant de décharge, c’est-à-dire la production par la décharge d’espèces chargées par unité detemps. Dans la géométrie et les conditions de fonctionnement choisies, des méthodes de mesure des flux d’ions en post-décharge ont alors été développées. Nous avons ainsi confirmé que la fraction d‘ions extraits de l’espace inter-électrodes résulte d’une compétition électro-hydrodynamique qui dépend de l’auto-organisation des filaments. En effet, les densités d’ions positifs et négatifs en post-DBD, ainsi que le rapport entre ces densités, critiques pour la charge d’aérosols, sont contrôlés par les champs électriques et le temps de transit des ions en post-décharge. Dans le chargeur post-DBD, les densités d’ions sont décroissantes. Toutefois, cette décroissance n’affecte pas les distributions de charges des aérosols qui sont constantes pour chaque taille quelle que soit la concentration d’aérosol. Dans ces conditions, les granulométries mesurées en post-neutraliseurs radioactif et DBD sont comparées afin de prouver que le neutraliseur post-DBD est viable pour la granulométrie des aérosols submicroniques. / The measurement of the size distribution of an aerosol (solid or liquid particles in suspension in agas) by electrical mobility analyses requires the neutralization of the aerosol. Neutralization consistsin imparting a charge distribution with a mean charge of 0 by the diffusion of bipolar ions on aerosol.We prove the feasibility of a post- Dielectric Barrier Discharge (DBD) bipolar charger as an alternativeto radioactive neutralizer subjected to legislative constraints. The electrical characterization of awire-to-wire DBD versus the gap, the voltage and the flow-rate highlights 3 kinds of selforganizationsof filaments versus voltage. Moreover, discharge current which represents the chargedspecies production per unit of time is evaluated. In the chosen geometry and operating conditions, apost-discharge ions flux measurement method was developed. We confirm that anelectro-hydrodynamic competition controls the extraction of ions from the gap. In fact, electric fieldsand transit time control positive and negative ions densities and the ratio between them which arecritical for aerosol charging. For the post-DBD charger, ions densities decrease in the charging zone.However, this decrease does not affect the aerosol charge distribution for each particle size withconcentration. In these conditions, the post-radioactive neutralizer and post-DBD neutralizer aerosolsize measurements are compared in order to prove that the post-DBD neutralizer is available forsubmicronic aerosols sizing.

Page generated in 0.035 seconds