O Brasil é o maior produtor de cana-de-açúcar, e entre os principais subprodutos dessa indústria está o melaço de cana-de-açúcar. Esse substrato é rico em carboidratos, apresentando potencial para ser utilizado na digestão anaeróbia para geração de biogás. Neste estudo, priorizou-se a produção de biogás em condições termofílicas (55°C) com a finalidade de comparação do sistema de duas fases (reator acidogênico seguido de reator metanogênico) e sistema de fase única (acidogênico e metanogênico em uma mesma unidade), utilizando o melaço como substrato. O sistema de duas fases baseou-se na separação da acidogênese e metanogênese. O reator acidogênico (ASTBR – A) foi operado com carga orgânica volumétrica (COV) de 60,0 g L-1d-1 e tempo de detenção hidráulico (TDH) de 4 horas. O reator metanogênico, sequencial ao acidogênico (ASTBR – M II) foi operado em dez fases, com COV variando de 0,6 a 10,0 g L-1d-1 e TDH de 40 e 24 horas. O sistema de fase única foi composto por um reator metanogênico (ASTBR – M I) operado em nove fases com COV entre 2,5 e 10,0 g L-1d-1 e TDH de 28 h. Bicarbonato de sódio (NaHCO3) foi adicionado na proporção de 1,00 g NaHCO3 g-1DQO para todas as fases do ASTBR M II. Para o ASTBR – M I, variou-se a concentração de 1,00 a 0,00 g NaHCO3 g-1 DQO no reator. Para o ASTBR A a porcentagem de hidrogênio (H2) no biogás foi de 51%, a produção volumétrica de hidrogênio (PVH) de 88,0 mL H2 L-1 h-1 e o rendimento de hidrogênio (HY) de 1,18 mol H2 molcarboidratos-1. O microrganismo predominante nesse reator foi o Thermoanaerobacterium, e a principal rota a do ácido lático. O reator ASTBR – M I sofreu acidificação após a retirada completa de alcalinizante, permitindo a detecção de H2 no biogás. Porém, a retomada da adição de NaHCO3 favoreceu o crescimento das arqueias, principalmente metanogênicas hidrogenotróficas. A comparação dos reatores metanogênicos foi realizada para fases com condições semelhantes (COV de 10 g L-1d-1 e 1,00 g NaHCO3 g-1DQO) e permitiu verificar melhor desempenho na produção de CH4 do ASTBR – M II. Em relação ao MY, a eficiência do ASTBR – M II foi 44% superior ao ASTBR M – I. / Brazil is the largest producer of sugarcane and one of the main sub-products of this industry is the molasses, which is rich in carbohydrates and can be used as a substrate for biogas production in anaerobic digestion. In this study, biogas production was evaluated under thermophilic conditions (55 °C) in a two-phases system (acidogenic reactor followed by methanogenic reactor) based on phase separation and a single-phase system (acidogenic and methanogenic microorganisms in a single unit) using molasses as the substrate. The acidogenic reactor (ASTBR-A) was operated under the organic loading rate (OLR) of 60.0 g L-1d-1 and hydraulic retention time (HRT) of 4 hours. The methanogenic reactor (ASTBR M II), which was sequential to acidogenic one, was operated in ten phases with OLR ranging from 0.6 to 10.0 g L-1d-1 and HRT of 40 and 24 hours. The single-phase reactor was composed of a methanogenic reactor (ASTBR -– M I) operated in nine phases with increasing OLR from 2.5 to 10.0 g L-1d-1 and HRT of 28 hours. Sodium bicarbonate (NaHCO3) was added in the ratio of 1.00 g NaHCO3 g-1COD in all phases of ASTBR – M II. For the ASTBR – M I, the concentration varied between 1.00 to 0.00 g NaHCO3 g-1COD. In the ASTBR – A, the percentage of hydrogen (H2) in the biogas was 51%, the volumetric hydrogen production (VHP) was 88.0 mL H2 L-1 h-1 and the hydrogen yield (HY) was 1.18 mol H2 molar-1carbohydrate. The predominant microorganism in this reactor was the Thermoanaerobacterium and the main metabolite route was the lactic acid. The ASTBR – M I suffered acidification after the complete removal of the alkalinizer allowing the detection of hydrogen in the biogas. However, the use of the alkalinizer after its complete removal from the system favored the growth of Archaeas, mainly the hydrogenotrophic methanogens. The comparison of the methanogenic reactors was carried out for phases with similar conditions (OLR of 10 g L-1d-1 and 1.00 g NaHCO3 g-1COD) and allowed to verify a better performance in the methane (CH4) production in the ASTBR – M II. Regarding the methane yield (MY), the efficiency of ASTBR – M II was 44% higher than ASTBR M – I.

O Brasil é o maior produtor de cana-de-açúcar, e entre os principais subprodutos dessa indústria está o melaço de cana-de-açúcar. Esse substrato é rico em carboidratos, apresentando potencial para ser utilizado na digestão anaeróbia para geração de biogás. Neste estudo, priorizou-se a produção de biogás em condições termofílicas (55°C) com a finalidade de comparação do sistema de duas fases (reator acidogênico seguido de reator metanogênico) e sistema de fase única (acidogênico e metanogênico em uma mesma unidade), utilizando o melaço como substrato. O sistema de duas fases baseou-se na separação da acidogênese e metanogênese. O reator acidogênico (ASTBR – A) foi operado com carga orgânica volumétrica (COV) de 60,0 g L-1d-1 e tempo de detenção hidráulico (TDH) de 4 horas. O reator metanogênico, sequencial ao acidogênico (ASTBR – M II) foi operado em dez fases, com COV variando de 0,6 a 10,0 g L-1d-1 e TDH de 40 e 24 horas. O sistema de fase única foi composto por um reator metanogênico (ASTBR – M I) operado em nove fases com COV entre 2,5 e 10,0 g L-1d-1 e TDH de 28 h. Bicarbonato de sódio (NaHCO3) foi adicionado na proporção de 1,00 g NaHCO3 g-1DQO para todas as fases do ASTBR M II. Para o ASTBR – M I, variou-se a concentração de 1,00 a 0,00 g NaHCO3 g-1 DQO no reator. Para o ASTBR A a porcentagem de hidrogênio (H2) no biogás foi de 51%, a produção volumétrica de hidrogênio (PVH) de 88,0 mL H2 L-1 h-1 e o rendimento de hidrogênio (HY) de 1,18 mol H2 molcarboidratos-1. O microrganismo predominante nesse reator foi o Thermoanaerobacterium, e a principal rota a do ácido lático. O reator ASTBR – M I sofreu acidificação após a retirada completa de alcalinizante, permitindo a detecção de H2 no biogás. Porém, a retomada da adição de NaHCO3 favoreceu o crescimento das arqueias, principalmente metanogênicas hidrogenotróficas. A comparação dos reatores metanogênicos foi realizada para fases com condições semelhantes (COV de 10 g L-1d-1 e 1,00 g NaHCO3 g-1DQO) e permitiu verificar melhor desempenho na produção de CH4 do ASTBR – M II. Em relação ao MY, a eficiência do ASTBR – M II foi 44% superior ao ASTBR M – I. / Brazil is the largest producer of sugarcane and one of the main sub-products of this industry is the molasses, which is rich in carbohydrates and can be used as a substrate for biogas production in anaerobic digestion. In this study, biogas production was evaluated under thermophilic conditions (55 °C) in a two-phases system (acidogenic reactor followed by methanogenic reactor) based on phase separation and a single-phase system (acidogenic and methanogenic microorganisms in a single unit) using molasses as the substrate. The acidogenic reactor (ASTBR-A) was operated under the organic loading rate (OLR) of 60.0 g L-1d-1 and hydraulic retention time (HRT) of 4 hours. The methanogenic reactor (ASTBR M II), which was sequential to acidogenic one, was operated in ten phases with OLR ranging from 0.6 to 10.0 g L-1d-1 and HRT of 40 and 24 hours. The single-phase reactor was composed of a methanogenic reactor (ASTBR -– M I) operated in nine phases with increasing OLR from 2.5 to 10.0 g L-1d-1 and HRT of 28 hours. Sodium bicarbonate (NaHCO3) was added in the ratio of 1.00 g NaHCO3 g-1COD in all phases of ASTBR – M II. For the ASTBR – M I, the concentration varied between 1.00 to 0.00 g NaHCO3 g-1COD. In the ASTBR – A, the percentage of hydrogen (H2) in the biogas was 51%, the volumetric hydrogen production (VHP) was 88.0 mL H2 L-1 h-1 and the hydrogen yield (HY) was 1.18 mol H2 molar-1carbohydrate. The predominant microorganism in this reactor was the Thermoanaerobacterium and the main metabolite route was the lactic acid. The ASTBR – M I suffered acidification after the complete removal of the alkalinizer allowing the detection of hydrogen in the biogas. However, the use of the alkalinizer after its complete removal from the system favored the growth of Archaeas, mainly the hydrogenotrophic methanogens. The comparison of the methanogenic reactors was carried out for phases with similar conditions (OLR of 10 g L-1d-1 and 1.00 g NaHCO3 g-1COD) and allowed to verify a better performance in the methane (CH4) production in the ASTBR – M II. Regarding the methane yield (MY), the efficiency of ASTBR – M II was 44% higher than ASTBR M – I.

Flow and transport phenomena in the subsurface often span a wide range of length (nanometers to kilometers) and time (nanoseconds to years) scales, and frequently arise in applications of CO₂ sequestration, pollutant transport, and near-well acid stimulation. Reliable field-scale predictions depend on our predictive capacity at each individual scale as well as our ability to accurately propagate information across scales. Pore-scale modeling (coupled with experiments) has assumed an important role in improving our fundamental understanding at the small scale, and is frequently used to inform/guide modeling efforts at larger scales. Among the various methods, there often exists a trade-off between computational efficiency/simplicity and accuracy. While high-resolution methods are very accurate, they are computationally limited to relatively small domains. Since macroscopic properties of a porous medium are statistically representative only when sample sizes are sufficiently large, simple and efficient pore-scale methods are more attractive. In this work, two Eulerian pore-network models for simulating single-phase flow and solute transport are developed. The models focus on capturing two key pore-level mechanisms: a) partial mixing within pores (large void volumes), and b) shear dispersion within throats (narrow constrictions connecting the pores), which are shown to have a substantial impact on transverse and longitudinal dispersion coefficients at the macro scale. The models are verified with high-resolution pore-scale methods and validated against micromodel experiments as well as experimental data from the literature. Studies regarding the significance of different pore-level mixing assumptions (perfect mixing vs. partial mixing) in disordered media, as well as the predictive capacity of network modeling as a whole for ordered media are conducted. A mortar domain decomposition framework is additionally developed, under which efficient and accurate simulations on even larger and highly heterogeneous pore-scale domains are feasible. The mortar methods are verified and parallel scalability is demonstrated. It is shown that they can be used as “hybrid” methods for coupling localized pore-scale inclusions to a surrounding continuum (when insufficient scale separation exists). The framework further permits multi-model simulations within the same computational domain. An application of the methods studying “emergent” behavior during calcite precipitation in the context of geologic CO₂ sequestration is provided. / text

Emerging energy storage applications are driving the demand for Li-ion battery positive electrode materials with higher energy densities and lower costs. The recent production of complete pseudo-ternary phase diagrams of the Li-Mn-Ni-O system generated using combinatorial methods has provided a greater understanding of the impact of initial composition, synthesis temperature, and cooling rate on the phases that form in the final materials. This thesis focuses on the synthesis and characterization of gram-scale positive electrode materials in the Li-Mn-Ni-O system. Structural analysis of these samples has resulted in the production of partial pseudo-ternary phase diagrams focusing on the positive electrode materials region of the Li-Mn-Ni-O system at 800°C and 900°C in air for both quenched and slow cooled compositions. These bulk-scale diagrams support the observations of the combinatorial diagrams, and show similar layered and cubic structures contained within several single- and multi-phase regions. The phases that form at each composition are shown to be dependent on both the reaction temperature and cooling rate used during synthesis. The electrochemical characterization of two composition series near Li2MnO3, one quenched and one slow cooled, is presented. The quenched compositions exhibited reversible cycling at 4.4 V, voltage plateaus and small increases in capacity above 4.6 V, and large first cycle irreversible capacity losses at 4.8 V. In the slow cooled series, all but one composition exhibited initial capacities below 100 mAh/g which began to continually increase with cycling, with several compositions exhibiting capacity increases of 300% over 150 cycles at 4.9 V. In both series, analysis of the voltage and differential capacity plots indicated that significant structure rearrangements are taking place in these materials during extended cycling, the possible origins of which are discussed. Finally, high precision coulometry studies of one Li-deficient and two Li-rich single-phase layered compositions are discussed. These materials exhibit minimal oxidation of simple carbonate-based electrolyte when cycled to high potential, with the Li-deficient composition producing less electrolyte oxidation at 4.6 V vs. Li/Li+ than commercial Li[Ni1/3Mn1/3Co1/3]O2 at 4.2 V. The inherent inertness of this composition may make it suitable for use as a thin protective layer in a core-shell particle.

ABSTRACT IMPLEMENTATION OF NORTHFINDING TECHNIQUES Oguz, Pinar MS, Department of Electrical and Electronics Engineering Supervisor: Assoc. Prof. Dr. T.Engin Tuncer June 2006, 131 pages The fundamental problem of navigation is to find the initial north angle of the body with respect to the reference frame. Determination of the north angle of the body frame is required in spacecraft, aircraft, sea-craft, land-craft and missile control and guidance. This thesis discusses implementation and comparison of four northfinding techniques. These are GPS (Global Positioning System) based with integer search, GPS based with Kalman filter, accelerometer based and IMU (Inertial Measurement Unit) based techniques. The north angle is determined by the processing of difference measurements of the GPS carrier phase between two antennas at GPS based northfinding techniques. Carrier phase ambiguity resolution is the main problem in GPS based techniques. Since, GPS receiver measures only the fractional part of the carrier phase. Therefore, integer part remains unknown. Two distinct ideas are applied to solve carrier phase ambiguities in two techniques. One of them is integer search on single phase difference. Suitable integer sets are checked on the cost function which is constructed from the single phase difference between two antennas. The other technique uses integer estimator and attitude estimator with Kalman filter rely on double difference phase measurements which are obtained from carrier phase differences of two antennas and two satellites at one instant. To test the GPS based techniques, a realistic GPS emulator is implemented. GPS emulator provides typical GPS raw navigation data including satellite positions, pseudoranges and carrier phases. Accelerometer based northfinding technique is composed of a vertically placed linear accelerometer on a rotating platform. The north angle is found by Coriolis acceleration due to Earth and platform rotation. Implementation problems of this technique in practice are discussed. IMU based northfinding technique has inertial sensor components such as gyroscopes and accelerometers to sense the Earth rotation rate and gravitational force respectively. The north angle is found by the processing of these inertial sensors output. Real set-up is established to test the IMU based technique.

Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη και κατασκευή ενός μετατροπέα για την οδήγηση ενός μονοφασικού επαγωγικού κινητήρα. Η εργασία αυτή εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών της Πολυτεχνικής Σχολής του Πανεπιστημίου Πατρών. Σκοπός είναι η μελέτη και κατασκευή ενός τριφασικού αντιστροφέα τάσης για τη λειτουργία και τον έλεγχο των στροφών ενός μονοφασικού επαγωγικού κινητήρα. Αρχικά μελετάται η βασική αρχή λειτουργίας του μονοφασικού επαγωγικού κινητήρα και αναλύονται οι τεχνικές εκκίνησης που χρησιμοποιούνται για σύνδεση του κινητήρα απευθείας στο δίκτυο. Ακόμα παρουσιάζονται τα ισοδύναμα κυκλώματα λειτουργίας του μονοφασικού επαγωγικού κινητήρα, η εξίσωση της ηλεκτρομαγνητικής ροπής του και προσομοιώνεται η λειτουργία του για τη μελέτη της στατικής συμπεριφοράς του. Στη συνέχεια γίνεται μια θεωρητική ανάλυση του κυκλώματος του τριφασικού αντιστροφέα τάσης που κατασκευάστηκε, καθώς και όλων των υπόλοιπων κυκλωμάτων που είναι αναγκαία για τη λειτουργία του. Επιπροσθέτως αναλύεται η μέθοδος παλμοδότησης των διακοπτικών στοιχείων του αντιστροφέα τάσης, που είναι η "Ημιτονοειδής Διαμόρφωση του Εύρους των Παλμών" (SPWM). Στο επόμενο βήμα αναλύονται τα τεχνικά χαρακτηριστικά όλων των κυκλωμάτων που κατασκευάστηκαν, και περιγράφεται ο κώδικας του προγράμματος του μικροελεγκτή, που χρησιμοποιήθηκε για την παραγωγή των παλμών. Τέλος, παραθέτουμε παλμογραφήματα και μετρήσεις που προέκυψαν από τα πειράματα που διενεργήθηκαν μετά την ολοκλήρωση της κατασκευής. / This diploma thesis discourse the analysis and construction of a converter topology for single phase induction motor drives. The project was based in the Laboratory of Electromechanical Energy Conversion of the department of Electrical and Computer Engineering of School Engineering of University of Patras. The objective of this project is the analysis and construction of a three phase voltage inverter to control the speed of a single phase induction motor. The first stage of this work is the study of the basic principle of operation of the single phase induction motor and the analysis of the starting techniques, used for the direct connection to the power grid. The equivalent circuits of the running single phase induction motor and the equation of the electromagnetic torque are also presented in this project. Following, there is a theoretical analysis of the three phase voltage inverter circuit, as well of all the remaining circuit, necessary for its function. Moreover the method of pulse generation for the switching elements of the voltage inverter is analyzed, which is the “Sinusoidal Pulse Width Modulation”. The next step is the analysis of the technical characteristics all of the circuits developed, as well the description of the program code for the microcontroller, used to produce the pulses. Finally oscillograph figures and measurements, occurred from the experiments transacted after the finalization of the construction, are adduced.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / Este trabalho apresenta o estudo, desenvolvimento e aplicação de novas técnicas de controle aos sistemas de geração de energia fotovoltaica, conectados à rede elétrica monofásica, visando a melhoria da eficiência destes sistemas em relação aos métodos de controle tipicamente utilizados. O trabalho é dividido em duas partes principais, as quais estão relacionadas ao rastreamento do ponto de máxima potência (Maximum Power Point Tracking – MPPT) e, depois, ao controlador interno dos conversores boost-quadrático – lado dos painéis fotovoltaicos – assim como aos controladores do inversor de tensão, no lado da rede elétrica monofásica. A primeira parte do trabalho consiste no desenvolvimento de um algoritmo de meta heurística para o MPPT, o qual é baseado no método do recozimento simulado (Simulated Annealing - SA) e tem como objetivo a determinação do ponto de máximo global, buscando soluções fora de uma vizinhança próxima, de modo a evitar o atracamento em máximos locais da curva de potência de saída do arranjo de painéis fotovoltaicos, melhorando, assim, o aproveitamento da energia em situações de sombreamento parcial. A segunda parte do trabalho apresenta o projeto de controladores baseados no modelo interno (Internal Model Control – IMC) com 1 grau de liberdade (1 Degree of Freedom – 1 DOF) aplicados, primeiramente, ao conversor CC-CC Boost Quadrático, utilizado para o MPPT, e, posteriormente, a um inversor de tensão com filtro LCL, conectado à rede elétrica monofásica, operando no modo de injeção de corrente. É apresentada a modelagem matemática de ambos os conversores e analisada a compensação da realimentação interna ao sistema do inversor de tensão, correspondente ao desacoplamento da tensão da rede, através da estratégia de alimentação à frente (Feedforward). Visando-se uma base de comparação, para a análise de desempenho do conversor IMC – 1DOF, também é aplicado ao sistema de injeção de corrente, o controlador Proporcional-Ressonante (P+Res). São apresentados resultados de simulação computacional e experimentais de ambos os 8 controladores, os quais permitem verificar o desempenho do sistema em situação de rede fraca e carga local não-linear. / This paper presents the study, development and application of new control techniques for photovoltaic power generation systems, connected to single-phase power grid in order to improve the efficiency of these systems in relation to control methods typically used. The work is divided into two main parts, which are related to tracking the maximum power point (Maximum Power Point Tracking - MPPT) and then the internal controller of boost quadratic converters - side of the photovoltaic panels - as well as the controllers the voltage inverter, the side of the single-phase mains. The first part of the work is the development of a heuristic goal algorithm for MPPT, which is based on the method of simulated annealing (Simulated Annealing - SA) and aims at determining the overall maximum point, seeking out solutions in a close vicinity, so as to prevent the docking local maxima in the curve of power output of the photovoltaic array, thereby improving the utilization of energy in partial shading situations. The second part presents the design of controllers based on internal model (Internal Model Control - IMC) with 1 degree of freedom (1 Degree of Freedom - 1 DOF) applied, first, the DC-DC Boost Quadratic converter, used for MPPT, and thereafter, a voltage inverter with LCL filter connected to the single phase power supply operating in current injection mode. A mathematical modeling of both converters and analyzed the compensation of internal feedback to the voltage inverter system corresponding to the disconnection of the mains voltage through the power strategy a head (feedforward). A basis of comparison for the performance analysis of IMC-1DOF converter is aiming at, is also applied to the current injection system, Proportional-Resonant Controller (P + Res). They are presented computer simulation and experimental results of both controllers, which allow you to check the system performance in low and non-linear local load network situation. / Tese (Doutorado)

Made available in DSpace on 2016-12-12T20:27:37Z (GMT). No. of bitstreams: 1 Jacson Luis Oliveira.pdf: 10477972 bytes, checksum: 1b64e6d37c97643852f0678c2a5c6d71 (MD5) Previous issue date: 2013-01-31 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / The goal of the present work is to evaluate control schemes which were developed to control the three-phase induction motor, applied in this work to control the single-phase induction motor. The development of control schemes to control fractional power electrical machines such as the single-phase induction motor has been in evidence due to the needs of improvements on efficiency energy demanded by the market. The constructive aspects of this motor does not allow to apply control schemes directly. Thus, it is necessary to model the single-phase induction motor as a two-phase motor. The model considers coordinates transformations to stationary systems. To fix the asymmetry of the motor windings, a symmetry transformation is required to apply the control schemes. Classical control schemes based on field-oriented control and direct torque control were evaluated. Numerical simulations were performed to review how these control schemes work and to verify the feasibility of experimental implementation. For control schemes based on field-oriented control, the rotor flux oriented control and the stator flux oriented control were evaluated. Some constraints on the classical direct torque control were noted due to the high switching frequencies. An alternative to the classical direct torque control to allow constant switching frequencies was evaluated. Experimental results were found by using a hardware system based on digital signal processor. / Este trabalho tem por objetivo avaliar estratégias de controle, originalmente desenvolvidas para controlar o motor de indução trifásico, aqui aplicadas ao controle motor de indução monofásico. O desenvolvimento de estratégias que abordam o controle de motores de potência fracionária tal como o motor de indução monofásico tem tido maior destaque devido a necessidade de melhorias na eficiência energética exigida pelo mercado. As características construtivas deste motor não permitem a aplicação direta destas estratégias, de modo que o modelamento do motor de indução monofásico deve ser realizado afim de obter o modelo em sua configuração bifásica. O modelo considera a transformação de coordenadas para um sistema de eixo estacionário e, para compensar a assimetria dos enrolamentos uma transformação de simetria é necessária para a aplicação das estratégias de controle. Foram avaliadas estratégias clássicas baseadas no controle por orientação de campo e controle direto de torque. Um estudo de simulação numérica é realizado para avaliar o comportamento destas estratégias de controle e verificar a viabilidade de implementação prática. Nas estratégias de controle por orientação de campo são analisados o controle vetorial com orientação por fluxo de rotor e o controle vetorial com orientação por fluxo de estator. Observou-se que há restrições na implementação prática de estratégias de controle baseadas no controle direto de torque clássico devido as altas freqüências de chaveamento requeridas. Uma alternativa ao controle direto de torque clássico que permite o uso de frequências fixas de chaveamento é avaliada. Resultados experimentais foram obtidos utilizando uma plataforma de hardware com processador digital de sinais.

Made available in DSpace on 2014-06-11T19:22:31Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-08-27Bitstream added on 2014-06-13T19:28:00Z : No. of bitstreams: 1 sampaio_lp_me_ilha.pdf: 1553174 bytes, checksum: 4a7ad1f1c4400135903509fd327b3112 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho propõe uma nova abordagem na metodologia de operação para o inversor Boost monofásico, como estrutura base para o aproveitamento de fontes alternativas e renováveis de energia elétrica. Considerando-se que equipamentos eletro/eletrônicos convencionais em CA (corrente alternada) necessitam, normalmente, de níveis e formato de tensão diferentes daqueles fornecidos por essas fontes de energia, o inversor proposto é uma estrutura integrada que tem a capacidade de operar como conversor elevador de tensão e inversor, apresentando um número reduzido de componentes e rendimento maior, quando comparado às formas tradicionais de se associar em cascata o conversor elevador com o inversor. O projeto convencional do inversor fonte de corrente (CSI) exige uma indutância elevada de entrada, além disso, o modelo a pequeno sinais do CSI é semelhante ao do conversor Boost no modo de condução contínua, apresentando um zero no semi-plano direito na função de transferência para o controle da tensão de saída, sendo que este zero causa o conhecido efeito de fase não-mínima. Desta forma, uma metodologia especial de projeto é apresentada resultando numa indutância Boost reduzida e numa técnica de controle utilizando um sistema multi-malhas, com alimentação direta, devidamente projetada de forma a possibilitar elevadas dinâmicas de transferência de energia. Adicionalmente, o inversor apresenta tensão de saída com reduzidas distorções harmônicas (DHT), número reduzido de componentes de potência e, consequentemente, elevada densidade de potência. Neste trabalho são apresentadas as análises qualitativa e quantitativa do inversor, a modelagem e técnica de controle proposta, metodologia de projeto, os principais resultados de simulação e experimentais com a finalidade de demonstrar a viabilidade de aplicação da proposta. / This work presents a new methodology for the operation and control of a single-phase current-source Boost Inverter, it is used as base structure for alternative and renewable electric energy sources. The electro/electronics devices normally require eletrical source in AC (alternate current) in different voltage levels and shapes those provided by the alternative and renewable electrical sources. The proposed inverter is an integrated structure able to operate as step-up DC-DC converter and inverter, it presents a reduced number of components, high efficiency when compared with the traditional technique of step-up and inverter for cascade association. The conventional design of current source inverter (CSI) require a large boost inductance, therefore, the small-signal model is similar to continuous-current-mode (CCM) Boost converter, which has a right-half-plane (RHP) zero in its control-to-output transfer function, and this RHP zero causes the well-known non-minimum-phase effects. In this context, a special design with small boost inductance and a multi-loop control is proposed in order to assure stability and very fast dynamics. Furthermore, the inverter presents output voltage with very low total harmonic distortion (THD), reduced number of components and high power density. In addition, this work presents the Boost CSI operation, the proposed control technique, the main simulation and experimental results in order to demonstrate the feasibility of the proposal.

Submitted by Maike Costa (maiksebas@gmail.com) on 2016-05-16T13:29:45Z No. of bitstreams: 1 arquivo total.pdf: 3062751 bytes, checksum: 5355db4f5e8fd0c5ecd86a23e5d0ad77 (MD5) / Made available in DSpace on 2016-05-16T13:29:45Z (GMT). No. of bitstreams: 1 arquivo total.pdf: 3062751 bytes, checksum: 5355db4f5e8fd0c5ecd86a23e5d0ad77 (MD5) Previous issue date: 2016-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior - CAPES / The single-phase extraction is based on the formation of a homogeneous mixture formed ideally between two immiscible phases (aqueous and organic) and a third component in the two immiscible phases, is added to achieve opalescence. In this mixture the complexation reactions occur and the subsequent extraction is performed by breaking the phase equilibrium by addition of an excess of the components of the mixture. However, the automation of this method by analyzing flow injection requires a device with a significant degree of complexity and difficult to control operating parameters. The objective of this study was to develop an automatic method of extracting single phase using flow-batch in question applied to the quantification of chromium in water and in commercial samples of vinegar by atomic absorption spectrometry graphite furnace. To this end, modifications have been made both in the mixing chamber (two outputs) as the extraction method, in which more suited to this proposal chemical systems were studied. The performance of the method was attested by statistical tests, in terms of precision (RSD <12%), accuracy (recovery between 82 and 108%), (m0 = 0.32 pg L-1 and LOQ = 0.86 μgL -1) and analytical frequency (26h-1). In this new strategy, the whole process of extraction was performed in mixing chamber quickly, simply and with adequate sensitivity to GF AAS technique. Moreover, it was possible to analyze samples of different matrices using the same method / A extração em fase única baseia-se na formação de uma mistura homogênea entre duas fases idealmente imiscíveis (uma aquosa e uma orgânica) e um terceiro componente miscível em ambas as fases, que é adicionado até atingir a opalescência. Nesta mistura ocorrem as reações de complexação e, a subsequente extração é realizada pela quebra do equilíbrio de fases através da adição de excesso de um dos componentes da mistura. Entretanto, a automação deste método através da análise por injeção em fluxo exige um aparato com significativo grau de complexidade e de difícil controle dos parâmetros operacionais. Assim, o objetivo deste trabalho foi desenvolver uma metodologia automática de extração em fase única utilizando análise em fluxo-batelada aplicada à quantificação de cromo em águas e amostras comerciais de vinagre por espectrometria de absorção atômica em forno de grafite. Para isto, foram feitas modificações tanto na câmara de mistura (duas saídas) como na técnica de extração, na qual foram estudados sistemas químicos mais adequados a esta proposta. O desempenho do método foi atestado através de testes estatísticos, em termos de precisão (RSD < 12%), exatidão (recuperação entre 82 e 108%), (m0 = 0,32 pg L-1 e LOQ = 0,86 μgL-1), e frequência analítica (26 h-1). Nesta nova estratégia, todo o processo de extração foi realizado na câmara de mistura de forma rápida, simples e com sensibilidade adequada para a técnica GF AAS. Além disso, foi possível analisar amostras de diferentes matrizes usando o mesmo método.