Thesis (MScEng)--University of Stellenbosch, 2003. / ENGLISH ABSTRACT: This thesis presents the design and implementation of shunt active power filtering algorithms for unbalanced, non-linear loads. A three-phase four-wire topology is developed in the dqO space. Based on this development an accurate dynamic system model, taking into account the effect of the neutral inductor is developed. The synchronous reference frame technique is expanded to enable the isolation of the zero sequence current component into its instantaneous active and reactive current components. Additionally a prediction method is proposed that will enable the proper prediction of the reference currents in a threephase four-wire system. Two categories of reference current signal tracking algorithms are investigated; namely the predictive current controller and the sliding mode current controller. A compensating technique is proposed to compensate for the effects that sampling and computational time delay have on the performance of the system. Additionally, an investigation is done into the effect that dead-time has on the performance of the system, and based on this investigation a dead-time compensating strategy is proposed. Finally simulation and practical results are provided to validate the discussed theories. / AFRIKAANSE OPSOMMING: Hierdie verhandeling ondersoek die ontwerp en implementering van parralel gekoppelde aktiewe filter algoritmes vir ongebalenseerde, nie-lineêre laste. 'n Drie-fase vier-draad topologie, asook 'n korrekte model van die dinamiese sisteem, wat die effek van die neutraal induktor insluit, is ontwikkel in die dqO ruimte. Die sinchroon verwysing vlak tegniek is uitgebrei om die isolering van die nul sekwensie stroom in onderskeidelik die oombliklike aktiewe en reaktiewe stroom komponente te verdeel. Addisioneel is a vooruitskatting tegniek aanbeveel wat die beheerder in staat sal stelom voldoende die verwysing strome vooruit te skat in 'n drie-fase vier-draad stelsel. Twee katagoriee van verwysing stroom volging algoritmes is ondersoek, naamlik die afskatting stroom beheerder en die gleiende modus stroom beheerder. 'n Effektiewe kompensasie tegniek is voorgestel om die effek van tydvertraging as gevolg van monstering en verwerking te elimineer. Addisioneel is die effek van dooie-tyd ondersoek en gebasseer op hierdie ondersoek is 'n effektiewe dooie-tyd kompensasie tegniek voorgestel. Laastens is simulasies en praktiese resultate verskaf om die werking van die voorgestelde teorie te bevestig.

Made available in DSpace on 2014-06-11T19:30:49Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-10-25Bitstream added on 2014-06-13T19:46:56Z : No. of bitstreams: 1 yoshimura_vl_dr_ilha.pdf: 20355281 bytes, checksum: 3940d4cd88accd5b22ddd0f62457078b (MD5) / Este trabalho aborda os Sistemas Chaveados Afins, em particular com questões de desempenho e observação de estado. Inicialmente, uma revisão do estado da arte foi realizada, que contém uma observação quanto à possibilidade de não existência de pontos de equilíbrio. Devido a esse fato, uma extensão das definições de estabilidade foi utilizada. Em seguida, questões geométricas foram levantadas para Sistemas Chaveados Lineares e, posteriormente estendidas para os Afins. Estas questões geométricas possibilitaram a verificação de alterações nas leis de chaveamento de forma a beneficiar o desempenho do sistema. Com a inserção da taxa de convergência garantida nas Desigualdades Matriciais Lineares existentes em trabalhos anteriores, chegou-se ao estabelecimento dos parâmetros de desempenho a serem aperfeiçoados. Na sequência, a composição de leis de chaveamento foi proposta através duas técnicas: a Função de Lyapunov Quadrática Chaveada e a Função de Lyapunov com Atratores Chaveados. Esta composição mostrou-se eficiente para a busca de um melhor compromisso entre parâmetros de desempenho conflitantes e, com efeito, pode melhorar um e outro parâmetro conflitantes. Por fim, uma técnica para a observação de estado em Sistemas Chaveados Afins foi proposta: o Observador de Luenberger Chaveado. Este observador foi analisado para os casos de reconstrução de estado, controle baseado em observação de estado e controle baseado em observação de estado na presença de modos não-Hurwitz. Para o primeiro caso, relaxações das Desigualdades Matriciais Lineares foram propostas com o uso do Lema da Projeção Recíproca e do Lema de Finsler. Ainda, uma otimização de norma das matrizes de ganho da saída foi feita, com o uso de Desigualdades Matriciais Lineares aplicadas à norma de Frobenius dessas matrizes... / This work deals with the Switched Affine Systems, particularly with their performance and state observation. Initially, a state-of-the-art review was developed, where an important point was raised on the possibility of absence of equilibrium points. This way, the stability concept was slightly modified. Then, geometrical questions were studied for the Switched Linear Systems and, subsequently extended for the Switched Affine Systems. Those geometrical questions allowed the verification of switching law alterations in such a way that their performance was enhanced. Thereofore, with the guaranteed convergence rate insertion in the existent LinearMatrix Inequalities in previous works, performance parameters to be increased were established. Following, a switching law composition method was proposed through two techniques: the Switched Quadratic Lyapunov Function and the Lyapunov Function with Switched Attractors. That composition showed itself efficient in a search for a better trade-off between conflicting performance parameters and, in fact, it may simultaneously enhance them. Finally, a technique for state observation in Switched Affine Systems was proposed: the Switched Luenberger Observer. This observer was analysed for the cases of state reconstruction, observer-based control and observer-based control in the presence of non-Hurwitz modes. For the first case, Linear Matrix Inequalities relaxations were proposed through the usage of the Reciprocal Projection Lemma and the Finsler’s Lemma. Yet, a norm optimization of the output gain matrices was achieved through the usage of Linear Matrix Inequalities applied to the Frobenius norm of those matrices. All the study was done with applications to the control of DC-DC converters, immediate examples of the Switched Affine Systems theory, given their nature

Electrospinning or electrostatic fibre spinning employs electrostatic force to draw fibres from a liquid, either a polymeric solution or a polymer melt in the form of a charged jet. The jet solidifies and is deposited on a collector in the form of a non-woven fibrous mat. Electrospun fibres have diameters between several nanometres to a few microns, which is one of the main advantages of the process, as materials at the nanoscale have shown great potential in a wide range of healthcare and energy applications. The initial selection of solvents to dissolve the polymer for production of electrospun defect-free nanofibres has generally been based on experience from similar polymer-solvent systems. The selection of a solvent is important to control the fibre surface morphology that would eventually determine the field of application for the electrospun nanofibrous structures. However, little attempt has been made to study the correlation between the solubility behaviour of the polymer in different solvents and the electrospinnability of the polymer solutions. From this perspective, the first part of this thesis focused on the selection of different solvents for the production of poly (lactic acid) (PLA) nanofibres. Solution properties were measured and the electrospun nanofibrous structures were analysed in terms of morphology and nanofibre diameter. Understanding the molecular interactions between polymer and solvents enables the correct solvent selection to ensure the desired nanofibrous structure. Solubility is not the only criterion for nanofibre formation from a polymer solution. Polymer concentration is one of the main factors affecting electrospinning. For this reason, a relationship between PLA concentration and nanofibre morphology was determined by solution property measurements. A three step systematic methodology has been proposed in this thesis in order to select appropriate solvent and polymer concentration for the production of homogeneous electrospun mats made of defect-free nanofibres. This methodology was validated for PLA nanofibres, but it can be used for a wide range of polymers. It simplifies the solvent selection process and can significantly improve the trial and error approaches used at present. Despite several models for electrospinning having been proposed to predict the behaviour of the electrospun jet, there are no simple methods for a priori prediction of the final morphology of the electrospun mat from the knowledge of solution properties and electrospinning process parameters. Moreover the prediction of nanofibre diameter is still a difficulty and little research has been done on this. For these reasons, the second part of this thesis is dedicated to understanding the effect of some process parameters on the jet electric current and hence on the morphology of PLA nanofibres. The values of current measured were used to verify an equation proposed in the literature for the prediction of the final diameter. The experimental diameter of the PLA nanofibres was compared with the predicted value. In the last chapter coaxial electrospinning was employed to produce PLA nanofibres with a core shell structure for the incorporation of a model hydrophilic drug in the nanofibre core. The large surface area to volume ratio of nanofibres offers the great advantage of higher efficiency of encapsulation and better control of the release profile compared with other drug delivery systems. Even though successful encapsulation of drug and proteins have been reported, it is not clear how to verify the continuous drug distribution in the core throughout the whole length of the fibre. The solution properties of both core and shell strongly affect the outcome of the electrospinning process. For this reason, several techniques have been used to verify the formation of a core shell structure and proper encapsulation of the drug. In addition, the efficiency of drug encapsulation was evaluated and drug release studies were performed.

Made available in DSpace on 2014-06-11T19:22:33Z (GMT). No. of bitstreams: 0 Previous issue date: 2013-11-28Bitstream added on 2014-06-13T20:49:15Z : No. of bitstreams: 1 000739759.pdf: 6607353 bytes, checksum: 355eecaadbec5a4f91eebb32742a33b9 (MD5) / A transmissão de energia elétrica em corrente contínua em alta tensão é uma tecnologia utilizada para atender os requisitos cada vez mais rigorosos para a transmissão de energia elétrica, como por exemplo: adoção de fontes de energia localizadas em regiões remotas, a expansão das cargas industriais e urbanas, transmissão de energia elétrica por canais marítimos, etc. Esta tecnologia tem-se demonstrado comprovadamente eficaz e altamente confiável com a capacidade de modular a potência transmitida de forma rápida e precisa, apresentando características vantajosas do ponto de vista técnico e econômico. Porém, este tipo de tecnologia possui a desvantagem operacional de gerar conteúdo harmônico no sistema devido ao comportamento não linear dos conversores de potência utilizados para a conversão de corrente alternada em corrente contínua. Neste contexto, com o intuito de aplicar a metodologia de cálculo do conteúdo harmônico para o conversor de seis pulsos, o objetivo central do trabalho consiste no desenvolvimento de um simulador computacional para a determinação das harmônicas de correntes geradas pelas estruturas chaveadas dos conversores estáticos trifásicos, considerando condições não ideais de operação. O principal diferencial deste aplicativo computacional é proporcionar um ambiente visual interativo e intuitivo para a realização das simulações, apresentando de uma forma clara o objetiva os resultados dos parâmetros calculados pelo aplicativo e o resultado de cálculo do conteúdo harmônico de corrente gerado pelos conversores de potência. / The power transmission in high voltage in direct current is a technology used to meet the increasingly stringent requirements for the transmission of electricity, such as: Adoption of energy sources located in remote areas, the expansion of industrial loads and urban, electrical transmission channels, marine, etc. This technology has demonstrated proven effective and highly reliable with the ability to model the power transmitted quickly and accurately, with advantageous features in terms of technical and economic. However, this type of technology has the disadvantage of generating harmonic content operating in the system due to nonlinear behavior of power converters used to convert alternating current into direct current. In this context, in order to apply the methodology of calculation of harmonic content for the six-pulse converter, the central objective of the work is to develop a software to determine the harmonic currents generated by switching structures of three-phase static converters, considering non-ideal operation. The main distinguishing feature of this application is to provide a computational interactive and intuitive visual environment to perform the simulations, showing a clear objective results of the parameters calculated by the application and the result of calculating the current harmonic content generated by power converters.

Made available in DSpace on 2014-06-11T19:22:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2014-01-20Bitstream added on 2014-06-13T20:27:27Z : No. of bitstreams: 1 paz_rr_me_bauru.pdf: 1210657 bytes, checksum: dda81099a2ae7f6313bd197c95e5e2ab (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / O objetivo deste trabalho consiste em realizar a análise de topologias de conversores CC-CC chaveados elevadores, com elevado ganho, para servirem de estágio de entrada em aplicações de sistemas de energias alternativas. As arquiteturas dos conversores são analisados e comparadas com relação aos seus aspectos construtivos e operacionais, incluindo os esforços de tensão e corrente nos interruptores e a característica da forma da onda de corrente drenada da fonte de alimentação. Os conversores elevadores avaliados na proposta são construídos empregando técnicas de arquitetura celular, considerando a associação paralela das células de potência de conversores elevadores, especificamente a célula Boost. Os modos de operação são analisados considerando o modo de condução contínua, modo de condução crítica e modo de condução descontínua. Para a associação paralela, a operação das células de potência é delimitada através da técnica de entrelaçamento. Os comportamentos dos conversores são avaliados considerando o desenvolvimento de modelos baseados na estratégia de modelação por valores médios, e ratificados por simulações computacionais / The goal of this work is to develop the analysis and modeling of step-up switched DC-DC converters architectures, with high gain, to serve as input stage in renewable energy systems applications. The power converter architectures are analyzed and compared with respect to their construction and operational aspects, including voltage and current stresses in the switches and the characteristic of the current waveform draw from the power source. The step-up converters are constructed using cellular archiecture, considering the parallel association of power cells, specifically the Boost power cell. The operating modes are analyzed considering continuous conduction mode, discontinuous conduction mode and critical conductional mode. In parallel association, the operation of power cells is performed using interleaved technique. The behavior of the converters are evaluated considering the development of models based on average modeling strategy averages, and ratified by computer simulations

Esta dissertação de mestrado propõe desenvolver a modulação vetorial (space vector – SV) para um inversor trifásico multinível híbrido assimétrico de nove níveis por fase com ponte-H em cascata (cascaded H-bridge – CHB). A verificação do desempenho ocorre através de simulações em software de simulação matemática, e posterior comparações entre duas simulações realizadas, como também a comparação da simulação de melhor desempenho com simulações obtidas com a modulação por síntese de formas de onda quase-quadradas e a modulação híbrida. Para tanto, inicialmente são revisadas as topologias de inversores de frequência mais tradicionais na literatura, identificando as suas características para justificar a escolha da topologia híbrida assimétrica. Posteriomente são revisados os métodos de modulação para inversores de frequência, identificando na modulação vetorial vantagens para sintetização das tensões de linha. Após, são relacioanados trabalhos envolvendo a modulação space vector aplicada em inversores multiníveis. Em seguida, a modulação SV é desenvolvida para o inversor trifásico multinível híbrido assimétrico de nove níveis por fase com ponte-H em cascata, sendo realizadas as seguintes etapas: definição dos possíveis vetores de comutação (estados de chaveamento) do inversor proposto no espaço tridimensional e no plano α-β; identificação dos planos limites e dos planos de separação dos setores no plano α-β; obtenção das matrizes de decomposição e; definição da sequência de comutação. Os resultados, obtidos por meio de software de simulação matemática, dos gráficos das tensões de fase e tensões de linha, assim como os valores de distorção harmônica total (total harmonic distortion – THD), fator de distorção de primeira ordem (first order distortion factor – DF1), tensão de modo comum, espectro harmônico dos sinais das tensões (de fase e de linha) são analisados, sendo os índices de THD, DF1 e tensão de modo comum comparados entre duas sequências de comutação diferentes para o inversor proposto. Também, os valores desses índices são comparados com outras técnicas de modulação (modulação por síntese de formas de onda quase-quadradas (QQ) e a modulação híbrida). O desenvolvimento e os resultados das simulações da modulação SV na topologia híbrida assimétrica de nove níveis proposta, assim como as análises das comparações, apontam resultados satisfatórios, identificando um potencial grandioso da modulação SV desenvolvida. / Submitted by Ana Guimarães Pereira (agpereir@ucs.br) on 2017-09-29T13:33:41Z No. of bitstreams: 1 Dissertacao Fernando Covolan Rosito.pdf: 6134096 bytes, checksum: e34621dae75a6139302a387eb73107b7 (MD5) / Made available in DSpace on 2017-09-29T13:33:41Z (GMT). No. of bitstreams: 1 Dissertacao Fernando Covolan Rosito.pdf: 6134096 bytes, checksum: e34621dae75a6139302a387eb73107b7 (MD5) Previous issue date: 2017-09-29 / This dissertation proposes to develop the space vector (SV) modulation for a three phase hybrid asymmetric multilevel inverter of nine levels per phase with cascaded H-bridge (CHB). Performance verification occurs through software simulations, and subsequent comparisons between two simulations performed, as well as the comparison of the best performance simulation with simulations obtained with the step wave modulation and hybrid modulation. To do this, the topologies of more traditional frequency inverters are reviewed in the literature, identifying their characteristics to justify the choice of hybrid asymmetric topology. Subsequently, the modulation methods for frequency inverters are reviewed, identifying the advantages of vector modulation for the synthesis of line voltages. Afterwards, works involving the space vector modulation applied in multilevel inverters are related. Then, the SV modulation is developed for a three phase hybrid asymmetric multilevel inverter of nine levels per phase with cascaded H-bridge (CHB). The following steps are performed: definition of the possible switching vectors (switching states) of the proposed inverter in three-dimensional space and in the plane α-β; identification of boundary planes and separation plans of sectors in the α-β plane; obtaining the decomposition matrices e; definition of the switching sequence. The results, obtained through mathematical simulation software, of the phase voltages and line voltages graphs, as well as the values of total harmonic distortion (THD), first order distortion factor (DF1), common mode voltage, harmonic spectrum of the voltage signals (phase and line) are analyzed, with THD, DF1 and common mode voltage indices being compared between two different switching sequences for the proposed inverter. In addition, the values of these indices are compared with other modulation techniques (step wave modulation and hybrid modulation). The development and results of the SV modulation simulations in the nine-level hybrid asymmetric topology proposed, as well as the comparative analyzes, indicate satisfactory results, identifying a great potential for SV modulation developed.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology. / Front-end power converters for nanosatellite applications demand better performance in accurate reference tracking because of the wide-range input voltage of the solar panels. The very tight output voltage requirements demand a robust, reliable, and high-efficiency converter. The control of such a converter is very complex and time consuming to design. Two commonly used control modes are current and voltage control. The design and implementation of a voltage controller for DC–DC power converter is simpler but compared to current mode controller, does not do provide for overcurrent protection. A single-ended primary inductance converter (SEPIC) was selected for this research work because of its ability to buck or boost the input voltage coupled with the ability to provide noninverting polarity with respect to the input voltage. Parameter values for the converter studied are used to analyse and design both the voltage and the current mode controllers for the nanosatellite front-end power converter. Output voltage reference tracking with step and ramp changes in the input voltage is evaluated in terms of the time taken to reach steady-state after the induced disturbances and either the overshoot or undershoot of the output voltage reference. The design of analogue pulse width modulation (PWM) study was carried out in order to drive the metal-oxide-semiconductor field-effect transistor (MOSFET) switch. For the two controllers, changes in the reference output voltage in response to load changes are also studied. An examination of the effects of solar radiation on the MOSFET switch was conducted; this switch is the main component of the front-end DC–DC power converter for a nanosatellite. At the more general level the examination also provided information on the response of the semiconductor technology in space application. The overall purpose of studying the MOSFET switch was to investigate the mechanisms that will facilitate its ability of switching ‘on’ and ‘off’ without failure as a result of solar radiation. The effects of solar radiation on MOSFET device in space, has resulted in more malfunctions of these devices in the past five years than over the preceding 40 years.

Thesis (MTech (Electrical Engineering))--Cape Peninsula University of Technology, 2017. / High Voltage Direct Current (HVDC) transmission is a safe and efficient technology designed to deliver large amounts of electrical power over long distances with minimal losses and at low costs. HVDC links require converters and filters at both terminal stations. The core component of the HVDC system is the power converter that connects the DC and AC systems together. The conversion from AC to DC, and vice versa, is achieved mainly through electronic switches called thyristors. The thyristor-based Line Commutated Converter (LCC) is a mature and trusted technology for HVDC transmission throughout the world. HVDC converters are bidirectional and can function in either rectification (AC to DC) or inversion mode (DC to AC). This is achieved when the voltage polarity across the converter gets swapped by the controllers, because current cannot change its direction in thyristors. In this thesis an analytical model of the HVDC converters is developed in the frequency domain by modelling it in DIgSILENT. The objective is to study the harmonics induced to the AC side from HVDC converters. Therefore, it is important in the real world to understand the principles, what causes harmonics to be generated in HVDC and transferred to the HVAC system. The objective of this thesis is to investigate the effectiveness of mitigation techniques used, on how they reduce harmonics by keeping these harmonic levels within specified values admissible by international standards (e.g. IEEE, etc).

Orientador: Edvaldo Assunção / Banca: Marcelo Carvalho Minhoto Teixeira / Banca: Rodrigo Cardim / Banca: Clóvis Antonio Petry / Banca: Cristiano Quevedo Andrea / Resumo: Este trabalho aborda os Sistemas Chaveados Afins, em particular com questões de desempenho e observação de estado. Inicialmente, uma revisão do estado da arte foi realizada, que contém uma observação quanto à possibilidade de não existência de pontos de equilíbrio. Devido a esse fato, uma extensão das definições de estabilidade foi utilizada. Em seguida, questões geométricas foram levantadas para Sistemas Chaveados Lineares e, posteriormente estendidas para os Afins. Estas questões geométricas possibilitaram a verificação de alterações nas leis de chaveamento de forma a beneficiar o desempenho do sistema. Com a inserção da taxa de convergência garantida nas Desigualdades Matriciais Lineares existentes em trabalhos anteriores, chegou-se ao estabelecimento dos parâmetros de desempenho a serem aperfeiçoados. Na sequência, a composição de leis de chaveamento foi proposta através duas técnicas: a Função de Lyapunov Quadrática Chaveada e a Função de Lyapunov com Atratores Chaveados. Esta composição mostrou-se eficiente para a busca de um melhor compromisso entre parâmetros de desempenho conflitantes e, com efeito, pode melhorar um e outro parâmetro conflitantes. Por fim, uma técnica para a observação de estado em Sistemas Chaveados Afins foi proposta: o Observador de Luenberger Chaveado. Este observador foi analisado para os casos de reconstrução de estado, controle baseado em observação de estado e controle baseado em observação de estado na presença de modos não-Hurwitz. Para o primeiro caso, relaxações das Desigualdades Matriciais Lineares foram propostas com o uso do Lema da Projeção Recíproca e do Lema de Finsler. Ainda, uma otimização de norma das matrizes de ganho da saída foi feita, com o uso de Desigualdades Matriciais Lineares aplicadas à norma de Frobenius dessas matrizes... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This work deals with the Switched Affine Systems, particularly with their performance and state observation. Initially, a state-of-the-art review was developed, where an important point was raised on the possibility of absence of equilibrium points. This way, the stability concept was slightly modified. Then, geometrical questions were studied for the Switched Linear Systems and, subsequently extended for the Switched Affine Systems. Those geometrical questions allowed the verification of switching law alterations in such a way that their performance was enhanced. Thereofore, with the guaranteed convergence rate insertion in the existent LinearMatrix Inequalities in previous works, performance parameters to be increased were established. Following, a switching law composition method was proposed through two techniques: the Switched Quadratic Lyapunov Function and the Lyapunov Function with Switched Attractors. That composition showed itself efficient in a search for a better trade-off between conflicting performance parameters and, in fact, it may simultaneously enhance them. Finally, a technique for state observation in Switched Affine Systems was proposed: the Switched Luenberger Observer. This observer was analysed for the cases of state reconstruction, observer-based control and observer-based control in the presence of non-Hurwitz modes. For the first case, Linear Matrix Inequalities relaxations were proposed through the usage of the Reciprocal Projection Lemma and the Finsler's Lemma. Yet, a norm optimization of the output gain matrices was achieved through the usage of Linear Matrix Inequalities applied to the Frobenius norm of those matrices. All the study was done with applications to the control of DC-DC converters, immediate examples of the Switched Affine Systems theory, given their nature / Doutor

Orientador: Flávio Alessandro Serrão Gonçalves / Coorientador: Diego Colón / Banca: Claudionor Francisco do Nascimento / Banca: Paulo José Amaral Serni / Resumo: O objetivo deste trabalho consiste em realizar a análise de topologias de conversores CC-CC chaveados elevadores, com elevado ganho, para servirem de estágio de entrada em aplicações de sistemas de energias alternativas. As arquiteturas dos conversores são analisados e comparadas com relação aos seus aspectos construtivos e operacionais, incluindo os esforços de tensão e corrente nos interruptores e a característica da forma da onda de corrente drenada da fonte de alimentação. Os conversores elevadores avaliados na proposta são construídos empregando técnicas de arquitetura celular, considerando a associação paralela das células de potência de conversores elevadores, especificamente a célula Boost. Os modos de operação são analisados considerando o modo de condução contínua, modo de condução crítica e modo de condução descontínua. Para a associação paralela, a operação das células de potência é delimitada através da técnica de entrelaçamento. Os comportamentos dos conversores são avaliados considerando o desenvolvimento de modelos baseados na estratégia de modelação por valores médios, e ratificados por simulações computacionais / Abstract: The goal of this work is to develop the analysis and modeling of step-up switched DC-DC converters architectures, with high gain, to serve as input stage in renewable energy systems applications. The power converter architectures are analyzed and compared with respect to their construction and operational aspects, including voltage and current stresses in the switches and the characteristic of the current waveform draw from the power source. The step-up converters are constructed using cellular archiecture, considering the parallel association of power cells, specifically the Boost power cell. The operating modes are analyzed considering continuous conduction mode, discontinuous conduction mode and critical conductional mode. In parallel association, the operation of power cells is performed using interleaved technique. The behavior of the converters are evaluated considering the development of models based on average modeling strategy averages, and ratified by computer simulations / Mestre