Die Bedeutung von Leistungshalbleitern mit großem Bandabstand (Wide Band Gap, WBG) nahm in den letzten drei Jahrzehnten kontinuierlich zu. Diese Bauelemente haben das Potenzial, Silizium (Si) - Bauelemente in bestimmten Anwendungen sowie Leistungs- und Frequenzbereichen zu ersetzen. Siliziumkarbid (SiC)-Leistungshalbleiter sind die gegenwärtig am Weitesten entwickelten WBG-Leistungshalbleiter. Dank besonderer Materialeigenschaften zeichnen sich SiC-Leistungshalbleiter im Vergleich zu Si-Bauelementen durch einen geringeren spezifischen Widerstand, eine höhere Schaltgeschwindigkeit, geringere schaltverluste sowie eine höhere maximale Sperrschichttemperatur aus. Die deutlich erhöhten Herstellungskosten limitieren den Einsatz von SiC-Leistungshalbleitern auf Anwendungen, in denen die Vorteile dieser Bauelemente die höheren Kosten überkompensieren und Systemvorteile ermöglichen. Heute werden SiC-Leistungshalbleiter z.B. in Solarwechselrichtern oder in Elektrofahrzeugen verwendet. Für Stromrichter industrieller elektrischer Antriebe ist die Kosten-Nutzen-Bilanz des Einsatzes von SiC-Leistungshalbleitern gegenwärtig nicht bekannt. Diese Fragestellung motiviert diese Arbeit. Die Auslegung sowie die daraus resultierenden Vor- und Nachteile eines Stromrichters mit SiC-Leistungshalbleitern für elektrische Industrieantriebe ist der Untersuchungsgegenstand dieser Arbeit. Zu diesem Zweck wurde unter Einhaltung industrieller Auslegungskriterien ein 240 kVA SiC-basierter Stromrichterdemonstrator als aktiver Gleichrichter am dreiphasigen 690 V Niederspannungsnetz untersucht. Auf der Basis einer Stromrichterauslegung für SiC- und Si-Leistungshalbleiter wurde ein theoretischer Vergleich von Kosten, Effizienz, Größe und Gewicht durchgeführt. Die Arbeit stellt zunächst den Stand der Technik für SiC-Leistungshalbleiter dar. Anschließend wird ein geeignetes SiC-MOSFET Module für den industriellen Stromrichter ausgewählt und bezüglich des Schaltverhaltens sowie der Parallelschaltung charakterisiert. Der Auslegung des Stromrichterleistungsteils liegen industrielle Anforderungen zu Grunde. Ein realisierter Demonstrator für einen netzseitigen Stromrichter (Active Front End) ist durch eine symmetrische Parallelschaltung von zwei SiC-Modulen, geeignete Ansteuerschaltungen (Gate Drive Units), eine niedrige Streuinduktivität im Kommutierungskreis sowie ein LCL-Filter mit Standard-Kernmaterialien gekennzeichnet. Der Stromrichtervergleich zeigt, dass der betrachtete Stromrichter mit SiC-Leistungshalbleitern im gesamten Betriebsbereich geringere Verluste verursacht als ein vergleichbarer Stromrichter mit Si-Leistungshalbleitern. Der SiC - basierte Stromichter ermöglicht auch eine deutliche Gewichtsreduktion bei ca. 89% der Systemkosten. Somit stellen SiC-Leistungshalbleiter eine attraktive technische Lösung für die untersuchte Anwendung eines aktiven Gleichrichters für industrielle elektrische Antriebe dar. / Wide bandgap (WBG) power semiconductors have drawn steadily increasing interest in power electronics in the last three decades. These devices have shown the potential of replacing silicon as the default semiconductor solution for several applications in determined power and frequency ranges. Among them the most mature WBG semiconductor material is silicon carbide (SiC), which presents several characteristics at the crystal level that translate in the potential of presenting lower resistivity, be able to switch faster with lower switching loss, and present both higher characteristics to tolerate and dissipate heat when com pared with silicon. However, the same characteristics that make it great also present a different set of drawbacks to be considered, which aligned with its increased cost make it challenging to assess if its advantages are justified for a particular application. Applications that highly value efficiency and/or power density are the most benefited, and converter solutions featuring the technology have already breached into these application markets. However in other applica tions, the line from which silicon carbide starts making sense in the cost/benefits/drawbacks balance is not clear. This is typically the case of industrial applications, which were the main focus and motivation of this work. Hence, in this work the main goal has been to determine the basic characteristics, advantages and limitations that SiC technology designs for industrial low voltage high power grid connected converters present. To that end, a 690 V, 240 kVA SiC-based grid-tied converter demonstrator following industrial design criteria has been developed. Then, based on this design procedure a theoretical comparison between a 690 V, 190 kVA SiC-based converter against a silicon-based converter designed for the same power output has been performed to compare them regarding cost, efficiency, size and weight. This work also comprises a thorough revision of the state of art of SiC devices, which led to the selection of the switching device. Additionally, a characterization of both single and parallel-connected operation of the semiconductor modules was performed, to determine the module characteristics and its suitability to build the SiC converter demonstrator. Results show that the converter demonstrator operates as designed, proving that is possible with the corresponding precautions to achieve: a low inductive power loop, balanced parallel connection of SiC modules, adequate driving circuits for the parallel-connected modules and an adequate filtering solution in compliance with grid-codes based on standard core materials for the selected switching frequency. Finally, the theoretical comparison between the two designed power converters shows that, attained to the conditions of the comparison, the SiC converter solution presents efficiency gains over the whole operating range, while presenting substantial weight savings at 89% of the costs of the Si-IGBT design, presenting itself as the cost-effective solution for the presented application requirements under the given design constraints.

Submitted by Elizabete Silva (elizabete.silva@ufes.br) on 2015-10-02T19:38:15Z No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) PLANEJAMENTO DA LOGÍSTICA DE SUPRIMENTO DE PLATAFORMAS OFFSHORE POR MEIO DE UM MODELO MATEMÁTICO 2L-CVRP COM FROTA HETEROGÊNEA E EQUILÍBRIO NÁUTICO.pdf: 4092400 bytes, checksum: 2f3e443433630154f11373b75d34eaa9 (MD5) / Approved for entry into archive by Morgana Andrade (morgana.andrade@ufes.br) on 2016-01-07T14:51:32Z (GMT) No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) PLANEJAMENTO DA LOGÍSTICA DE SUPRIMENTO DE PLATAFORMAS OFFSHORE POR MEIO DE UM MODELO MATEMÁTICO 2L-CVRP COM FROTA HETEROGÊNEA E EQUILÍBRIO NÁUTICO.pdf: 4092400 bytes, checksum: 2f3e443433630154f11373b75d34eaa9 (MD5) / Made available in DSpace on 2016-01-07T14:51:32Z (GMT). No. of bitstreams: 2 license_rdf: 23148 bytes, checksum: 9da0b6dfac957114c6a7714714b86306 (MD5) PLANEJAMENTO DA LOGÍSTICA DE SUPRIMENTO DE PLATAFORMAS OFFSHORE POR MEIO DE UM MODELO MATEMÁTICO 2L-CVRP COM FROTA HETEROGÊNEA E EQUILÍBRIO NÁUTICO.pdf: 4092400 bytes, checksum: 2f3e443433630154f11373b75d34eaa9 (MD5) Previous issue date: 2015 / CAPES / O petróleo é um importante recurso no mundo atual e sua exploração no Brasil se baseia, sobretudo, na exploração em águas profundas, para a qual são implantadas plataformas offshore. Como estas plataformas estão distantes da costa brasileira e isoladas, é fundamental planejar a logística de suprimento, que inclui, entre outros elementos, as embarcações de apoio offshore, as quais são responsáveis por abastecer as plataformas e constituem um recurso caro. Nos sistemas logísticos, é essencial planejar e gerenciar as atividades de transportes de cargas, pois os custos relativos ao transporte representam uma grande parcela dos custos logísticos totais. Portanto, no contexto analisado, é importante minimizar os custos de transporte por meio de um eficiente planejamento dos navios de suprimento. Nesse sentido, há dois aspectos centrais na gestão de distribuição logística: problemas de roteamento de veículos, usados para determinar a rota ótima, e problemas de carregamento, usados para definir a melhor maneira de carregar mercadorias dentro dos veículos utilizados no transporte. Visando a criação de rotas e a arrumação bidimensional de cargas, foi proposto na literatura o Problema de Roteamento de Veículos Capacitados com Restrições de Carregamento Bidimensional (Capacitated Vehicle Routing Problem with Two-dimensional Loading Constraints – 2L-CVRP). Esta dissertação tem por objetivo propor um modelo matemático de Programação Linear Inteira Mista baseado no 2L-CVRP aplicado ao planejamento da logística de suprimento de plataformas offshore para criar rotas considerando o equilíbrio náutico e a melhor arrumação das cargas no convés, denominado Weight Balance Two-Dimensional Loading Heterogeneous Fleet Vehicle Routing Problem (WB2L-HFVRP). Este modelo se diferencia por considerar frota heterogênea e utilizar uma função objetivo que visa minimizar o número de navios, a distância navegada e a diferença entre os pesos distribuídos entre os bordos do navio. Testes em instâncias baseadas em dados reais da Petrobras foram feitos no CPLEX 12.6 e mostraram uma redução de até 25% em relação à distância real navegada. / Oil is an important resource in today's world and its exploitation in Brazil is based mainly on deepwater exploration, for which offshore platforms are deployed. As these platforms are isolated and distant from the Brazilian coast, it is essential to plan the supply logistics, which includes, among other elements, the offshore support vessels, which are responsible for supplying the platforms and are an expensive resource. On logistics systems, is essential to plan and manage the activities of freight transport, because the transport costs represent a large portion of total logistics costs. Therefore, in the analyzed context, it is important to minimize transportation costs through efficient planning of the supply vessel. In this sense, there are two central aspects in the management of logistics distribution: Vehicle Routing Problems, used to determine the optimal route, and Loading Problems, used to define the best way of carrying goods in vehicles used for transport. Aiming to create routes and the two-dimensional storage of cargo, has been proposed in the literature the Capacitated Vehicle Routing Problem with Two-dimensional Loading Constraints (2L-CVRP). This essay aims to propose a mathematical model of Mixed Integer Linear Programming based on 2L-CVRP applied to planning the supply logistics of offshore platforms to create routes considering the nautical balance and better storage of cargo on deck, named Weight Balance Two-Dimensional Loading Heterogeneous Fleet Vehicle Routing Problem (WB2L-HFVRP). This model differs from other models because it considers heterogeneous fleet and uses a objective function that aims to minimize the number of ships, sailed distance, and the difference between the weights distributed between the sides of the ship, the nautical balance. Tests on instances based on real data from Petrobras were made in CPLEX 12.6 and showed a reduction of up to 25% compared to the actual sailed distance.

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[pt] O conceito de jeitinho está presente em uma série de discursos que expressam um conjunto de valores que os brasileiros percebem como sendo seus. De fato, o jeitinho não pode ser correlacionado exclusivamente a uma camada ou classe social. Ele se constitui como uma prática social conhecida e legitimada por todos os segmentos da sociedade brasileira. Dessa forma, com base em uma perspectiva social da linguagem, a abordagem desse conceito em um contexto de ensino de português do Brasil como língua estrangeira ou segunda língua mostrase relevante. Nessa dissertação, abordamos o conceito de jeitinho por meio da leitura e análise de três crônicas de autores brasileiros. Esse gênero apresenta uma linguagem singular: é um produto do discurso jornalístico e, ao mesmo tempo, inclui-se entre os gêneros literários. A análise das crônicas foi realizada sob a perspectiva da semiótica discursiva, tendo por objetivo a busca de sentidos que se relacionam ao conceito de jeitinho. Com base em uma perspectiva intercultural, os aprendizes estrangeiros podem, por meio da leitura das crônicas, entrar em contato com certos aspectos culturais que envolvem o conceito de jeitinho na sociedade brasileira. Acreditamos que o resultado dessa pesquisa possa contribuir para promoção de uma consciência cultural crítica no âmbito de ensino do português do Brasil. / [en] The concept of jeitinho is present in a series of discourses that express a set of values that Brazilians perceive as their own. In fact, jeitinho cannot be correlated exclusively to a social class or select group. It is constructed as a social practice known and legitimized by all segments of Brazilian society. Thus, based on a social perspective of the language, the approach of this concept in a context of teaching Brazilian Portuguese as a foreign language or second language is relevant. In this dissertation, we propose to approach the concept of jeitinho through the reading and analysis of chronicles of three Brazilian authors. This genre presents a unique language which is a product of journalistic discourse and, at the same time, is included among recognized literary genres. The analysis of chronicles was carried out from the perspective of discursive semiotics, aiming to search for meanings that are related to the concept of jeitinho. Based on an intercultural perspective, foreign learners can touch on certain cultural aspects that involve the concept of jeitinho in Brazilian society, through the reading of chronicles. We believe that the result of this research may contribute to the promotion of a critical cultural awareness within the scope of the teaching of Brazilian Portuguese.