Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This Master Thesis presents the study and proposes a digital control system applied to the PFC boost converter operating in mixed conduction mode. The motivation to this subject, a bibliographic review of the existing current control techniques and the objectives of this work are presented in the first chapter. The control system is composed of a current loop, which has the objectives to provide low harmonic content to the input current and high power factor to the converter, and a voltage loop, which has the goal to regulate the output voltage of the converter. Initially, the study of the conduction modes of the PFC boost converter, highlighting their operation conditions, and details of the mixed conduction mode operation are showed. Next, two predictive digital current controllers with feedforward action are approached in details, including the equations deduction, block diagram, operation process, design, simulation results and parametric variation analysis. A comparative analysis between both controllers is also accomplished. The proportional-integral voltage controller is presented following, comprising its structure, design and simulation results. After, issues related to the practical implementation of the converter and control system, as the converter design and the control device programming, are shown. Finally, the experimental results obtained through the implementation of the proposed system, including the waveforms acquired using a prototype constructed in laboratory and the quality indexes as the power factor and the total harmonic distortion, are presented with the purpose to validate and prove the content of this work. / Esta Dissertação de Mestrado apresenta o estudo e propõe um sistema de controle digital para o conversor boost PFC operando no modo de condução mista. A motivação para este assunto, uma revisão bibliográfica das técnicas de controle de corrente existentes e os objetivos do trabalho são apresentados no capítulo introdutório. O sistema de controle é composto de uma malha de corrente, que tem por objetivo proporcionar baixo conteúdo harmônico para a corrente de entrada e alto fator de potência para o conversor, e uma malha de tensão, que tem por objetivo regular a tensão de saída do conversor. Inicialmente, o estudo dos modos de condução do conversor boost PFC, destacando as suas condições de operação, e detalhes da operação no modo de condução mista são mostrados. Em seguida, dois controladores digitais preditivos de corrente com ação feedforward são abordados em detalhes, incluindo o equacionamento, diagrama de blocos, funcionamento, projeto, resultados de simulação e análise da variação paramétrica. Uma análise comparativa entre ambos também é realizada. O controlador proporcional-integral de tensão é abordado na seqüência, compreendendo sua estrutura, projeto e resultados de simulação. Posteriormente, questões relativas à implementação prática do conversor e do sistema de controle, como o projeto do conversor e a programação do dispositivo de controle, são mostradas. Por fim, os resultados experimentais obtidos com a implementação do sistema proposto, incluindo as formas de onda adquiridas em um protótipo construído em laboratório e os índices de qualidade como o fator de potência e a distorção harmônica total, são apresentados com o intuito de validar e comprovar o conteúdo deste trabalho.

Made available in DSpace on 2014-06-11T19:22:35Z (GMT). No. of bitstreams: 0 Previous issue date: 2006-09-11Bitstream added on 2014-06-13T20:09:51Z : No. of bitstreams: 1 santelo_tn_me_ilha.pdf: 2212208 bytes, checksum: a764ab5d18d16ce24639a45f6f1553bd (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Este trabalho apresenta um novo conversor PWM monofásico CA-CC, com um único estágio de retificação e correção do fator de potência, utilizando a célula de comutação de três estados. É demonstrado o conversor proposto empregando duas destas células, em substituição as configurações convencionais de duplo estágio, um estágio retificador e outro pré-regulador. A célula de comutação de três estados é composta basicamente por dois interruptores ativos, dois passivos e dois indutores acoplados magneticamente. A topologia desta célula permite que apenas metade da potência de entrada seja processada pelos interruptores ativos, reduzindo assim a corrente de pico sobre estes à metade do valor da corrente de pico da entrada, tornando importante para aplicações em potências mais elevadas. O volume dos elementos reativos (indutores e capacitores) é reduzido, pois, por características topológicas, a freqüência da ondulação da corrente e da tensão é o dobro da freqüência de operação dos interruptores, sendo assim, possível operar o conversor com menores freqüências, diminuindo consequentemente as perdas na comutação. As perdas totais são distribuídas entre todos semicondutores, facilitando a dissipação de calor. O paralelismo dos interruptores é muito atraente para a configuração do circuito estudado, possibilitando o uso de interruptores mais baratos. Outra vantagem é possuir uma menor faixa de operação na região de descontinuidade, ou seja, a faixa de operação no modo de condução contínua é ampliada. É realizado um estudo do conversor boost CC-CC operando com razão cíclica (0 < D < 0,5) e (0,5 < D < 1). Em seguida este conversor é empregado, operando em toda faixa de variação da razão cíclica (0 LÜD LÜ1), no conversor CA-CC de estágio único. O circuito do conversor em questão funciona em malha fechada utilizando o circuito integrado UC3854 para... / This work presents a new AC-to-DC PWM single-phase converter, with only one stage including rectification and power factor correction, using the three-state switching cell. It is demonstrated the proposed converter using two of these cells, instead of the conventional configurations that use a rectifier stage and a high-frequency pre-regulator. The three-state switching cell comprises two active switches, two diodes and two coupled inductors. In this topology only part of the input energy is processed by the active switches, reducing the peak current in these switches in a half of the peak value of the input current, making this topology suitable to the operation in larger power levels. The volume of the power reactive elements (inductors and capacitors) is also decreased since the ripple frequency on the output is twice the switching frequency. For a smaller operating frequency, the switching losses are decreased. Due to the topology of the converter, the total losses are distributed among all semiconductors, facilitating the heat dissipation. The parallelism of switches is very attractive for the studied configuration, facilitating the use of cheaper switches. Another advantage of this converter is the smaller region to operate in discontinuous conduction mode or, in other words, the operation range in continuous conduction mode is enlarged. It is developed a study of the DC-to-DC boost converter operating with duty (0 < D < 0,5) and (0,5 < D < 1). Then, this converter was used in full variation range of the duty-cycle (0 < D < 1) in the AC-to-DC single-stage converter. The circuit of this issue converter works with a feedback control line using the integrated circuit UC3854 to do the control in continuous conduction mode for input current with instantaneous average mode. Besides the mathematical analysis and development through...

Made available in DSpace on 2014-06-11T19:22:36Z (GMT). No. of bitstreams: 0 Previous issue date: 2008-05-14Bitstream added on 2014-06-13T18:08:35Z : No. of bitstreams: 1 brito_mag_me_ilha.pdf: 1676298 bytes, checksum: 52c7782c077571e9aa0d479e44fb3971 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Este trabalho trata da análise, desenvolvimento e implementação de um estágio Pré- Regulador Retificador Boost de alto fator de potência, para servir como fonte de alimentação para sistemas de iluminação fluorescente multi-lâmpadas, com potência de até 1.200 watts e com índices de qualidade tanto para a fonte de alimentação em corrente alternada quanto para o sistema de iluminação. Este conversor será controlado de forma digital, através da técnica dos valores médios instantâneos da corrente de entrada, desenvolvido através da linguagem de descrição de hardware VHDL (VHSIC HDL – Very High Speed Integrated Circuit Hardware Description Language) e implementado em um dispositivo FPGA (Field Programmable Gate Array) Spartan 3. Neste trabalho são apresentadas análises matemáticas, para a obtenção das funções de transferência pertinentes ao projeto dos compensadores, onde será aplicada uma metodologia de projeto capaz de projetar estes compensadores utilizando os diagramas de Bode, de módulo e de fase, e ainda contemplar as influencias dos dispositivos A/D, D/A e do processador digital de sinais. Isto eliminará os erros presentes nos projetos via aproximação e permitirá a diminuição das taxas de aquisição necessárias. O projeto é simulado e validado através da plataforma MatLab/Simulink, onde são apresentados resultados para o regime permanente e para transitórios de carga e da tensão de alimentação. Além disso, o controle do conversor através da linguagem VHDL, usando o modelo comportamental num estilo de projeto topdown, é apresentado e também validado através de simulação. Ademais, um sucinto estudo dos reatores eletrônicos convencionais é apresentado, com o intuito de sevir como base para o desenvolvimento de um filtro capaz de barrar as componentes em ca da corrente que circula entre o capacitor de saída... / This work presents the analysis, development and implementation of a single-phase power factor correction (PFC) pre-regulator rectifier, based on boost circuit, to act as a power supply for 1.200 watts multi-lamp fluorescent systems. The converter’s digital control will be implemented using the average current mode control, based on VHDL language (VHSIC HDL – Very High Speed Integrated Circuit Hardware Description Language) and using a FPGA (Field Programmable Gate Array) device. In this work, the mathematical analyses of the converter´s model are developed in order to obtain the proper transfer functions to design voltage and current digital compensators. The methodology applied at the digital design is capable to deal with the Bode diagrams and incorporate the analog to digital converter, the digital to analog converter and the digital signal processor, eliminating the uncertainties involving approximation methodologies and minimizing the necessity of high level of acquisition rates. This project is evaluated through MatLab/Simulink, showing results for steady-state operation and dynamics in order to analyze the converter’s response. Moreover, the converter’s digital control is based on VHDL language, using the behavioral modeling in a top-down project style, which is presented and validated through simulation results. In addition, the behavior of the conventional electronic ballasts are presented in order to help in the development of a filter, capable to impede the circulation of the AC components of the ballast current throught the feeding link, guaranteeing the continuous current conduction, among the boost capacitor and the electronic ballasts. Finally, this work presents the laboratorial development of this PFC with digital control, where the prototype was evaluated through experimental results.

Orientador: Carlos Alberto Canesin / Banca: Falcondes Jose Mendes de Seixas / Banca: Dionizio Paschoareli Junior / Banca: Luiz Carlos de Freitas / Banca: João Batista Vieira Junior / Resumo: Esta tese apresenta o desenvolvimento e os principais resultados para um retificador monofásico pré-regulador "boost" para aplicação em sistema trólebus, possibilitando sua alimentação em corrente alternada (CA) ou em corrente contínua (CC), mantendose o sistema tradicional de distribuição da alimentação a dois fios. A estrutura proposta é composta por um retificador monofásico convencional, conectado a um conversor "boost" entrelaçado com cinco células, operando no modo de condução descontínua (MCD), reduzindo as perdas de comutação no diodo "boost", interferências eletromagnéticas (EMI - electromagnetic interference) e propiciando o controle de forma simples, robusta e confiável para a estrutura. Além disso, devido às características das linhas de distribuição, a estrutura proposta pode atuar como conversor CA para CC ou CC para CC, fornecendo nível de tensão dentro da faixa adequada para o barramento CC. Quando alimentado pelo sistema em CA monofásico, o conversor propicia elevado fator de potência com reduzida distorção harmônica total de corrente (DHTi), atendendo plenamente às restrições da norma internacional IEC 61000-3-4. Adicionalmente, uma técnica de correção para a corrente de entrada, utilizando referência da tensão de entrada, é utilizada para garantir os baixos níveis de distorção harmônica, uma vez que a operação do pré-regulador retificador "boost" entrelaçado em MCD ocorre com reduzido ganho estático. Para a implementação do controle da regulação de tensão e correção da corrente de entrada, é empregado um dispositivo FPGA (field programmable gate array) utilizando linguagem de descrição de hardware (VHDL - verilog hardware description language). Utilizando o mesmo dispositivo FPGA, foi desenvolvido um controle de gerenciamento da operação, promovendo a comutação automática quando... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: This thesis presents the development and experimental analysis of a special input stage converter for a Trolleybus type vehicle allowing its operation in AC (two wires, singlephase) or DC distribution networks. The proposed input stage architecture is composed by a conventional single-phase rectifier connected with a five interleaved boost rectifiers operating in discontinuous conduction mode (DCM), avoiding commutation boost diode losses, electromagnetic interference (EMI) and promoting simple control actions, robustness and reliability for the structure. Furthermore, due to the power lines characteristics, the proposed input power structure can act as AC to DC or as DC to DC converter providing a proper DC output voltage range required to the DC bus. When operating as AC to DC, the converter is capable to provide high power factor with reduced input current harmonic distortion, complying with the imposed restrictions by IEC 61000-3-4 standard. In addition, a special input current correction technique, using input voltage reference, is employed in order to achieve low harmonic distortions considering operation with low voltage static gain for the DCM interleaved boost rectifier pre-regulator. For implementation of the output voltage control and input current correction was used a field programmable gate array (FPGA) device with verilog hardware description language (VHDL). In addition using the same FPGA device, a management control system was implemented, promoting the required automatic operation changes when the vehicle is commuted from the DC power supply to the AC power supply and viceversa, keeping the original electrical DC bus characteristics for the trolleybus. After a brief review, a development work process is presented, containing the design methodology with all needed mathematical expressions, simulations, control circuits, as well as a 3D Computer-Aided Designs... (Complete abstract click electronic access below) / Doutor

Les systèmes de transmission de l’information sans fil connaissent un essor considérable et sont intégrés dans la plupart des systèmes électroniques modernes. De manière plus spécifique, la consommation énergétique de la fonction amplification de puissance RF, qui constitue le cœur de ce travail de recherche, est un enjeu économique et écologique de premier plan. Dans ce sens, ce travail présente une architecture de polarisation de drain dynamique permettant de maintenir un rendement énergétique élevé sur une large dynamique de puissance de sortie. La conception et la réalisation d’un amplificateur de puissance RF large bande, d’un modulateur de polarisation de drain haute fréquence et d’un pilote de grille en technologie GaN sont présentés. L’architecture proposée démontre une amélioration du rendement énergétique global. Une focalisation sur la problématique de couplage non-linéaire entre l’amplificateur de puissance RF et le module d’alimentation agile met en évidence les répercussions de cette méthode sur l’intégrité du signal. Une étroite impulsion de polarisation de grille est appliquée afin d'atténuer l’impact de la polarisation dynamique de drain sur les formes d'onde de l'enveloppe du signal RF amplifié. Une validation expérimentale du démonstrateur proposée est effectuée pour un signal impulsionnel RF multi-niveaux de test. Cette méthode permet de maintenir un facteur de forme de l’enveloppe du signal de sortie RF quasi-rectangulaire sans impact majeur sur les performances globales énergétiques. / Wireless communications are experiencing tremendous growth and are integrated into most modern electronic systems. More precisely, saving energy consumption of RF power amplifier is the core of this thesis work. This work presents a dynamic drain bias architecture used to keep a high efficiency over a large output power range. Design and implementation of a wideband RF power amplifier, a drain supply modulator and a gate driver circuit in GaN technology are presented. The built-in prototype demonstrates an overall efficiency improvement. A specific focus on non-linear interaction between the RF power amplifier and the drain supply modulator highlights the effects of this technique on the output envelope signal shape. A narrow pulse gate bias peaking preceding drain bias voltage variations is applied in order to mitigate drain bias current, voltage overshoot and power droop, thus improving pulse envelope waveforms of the RF output signal. An experimental validation of the proposed demonstrator is performed for a RF pulsed test sequence having different power levels. This way enables to keep rectangular pulse envelope shape at the RF output signal without any major impact on overall efficiency performances.

DC system and DC microgrids are gaining popularity in recent times. This thesis suggests a method to state the workability of a DC based PV system using the softwares Simulink, PVsyst and HOMER. The aims of this project include suggesting a DC based architecture, finding out the performance ratio and a cost analysis. The advantages of the DC based system, the cost benefits associated with it and its performance will determine its feasibility.   Not many softwares have the functionality to simulate DC based PV systems. PVsyst is considered as one of the most sought-out softwares for the simulation of PV systems. It can simulate a DC based PV system but has a lot of limitations when it comes to the architecture and voltage levels. Due to these factors, the results from softwares Simulink, Homer and PVsyst are used to calculate the performance ratio of the suggested DC system.    The simulation of the DC system involves modelling of a DC-DC converter. DC-DC converters are used in HVDC transmission and are being considered for small scale and medium scale microgrids. The DC-DC boost converter is coupled with a MPPT model in Simulink. P and O algorithm is chosen as the MPPT algorithm as it is simple and widely used. The Simulink model of PV array and MPPT based boost converter provides the power output at the needed voltage level of 350V. The input for the Simulink model is obtained from the results of HOMER. The inputs include solar irradiation data and cell temperature. The same input data is used for the simulations in HOMER and PVsyst. The performance ratio is obtained by combining the power output from Simulink with the other aspects of the system from PVsyst. The performance ratio is done only for the month of January due to the limitations in Simulink. The performance ratio is found out to be 65.5 %.   The cost estimation is done for the distribution and power electronics aspects of the system. It is found out that the cost associated with the conductors will have an impact on the total cost only if the conductors used for distribution is more in length. The cost associated with the power converters will make a difference in total cost only if the system is within the range of 100kW. The study shows the workability of the PV based DC system based on the above mentioned aspects

The grid-connected photo-voltaic (PV) system is one of the most promising renewable energy solutions which offers many benefits to both the end user and the utility network and thus it has gained the popularity over the last few decades. However, due to the very nature of its invariability and weather dependencies, the large scale integration of this type of distributed generation has created challenges for the network operator while maintaining the quality of the power supply and also for reliable and safe operations of the grids. In this study, the behavioral impact of large scale PV system integration which are both steady and dynamic in nature was studied.  An aggregate PV model suited to study the impacts was built using MATLAB/Simulink.  The integration impacts of PV power to existing grids were studied with focus on the low voltage residential distribution grids of Mälarenergi Elnät AB (10/0.4 kV). The steady state impacts were related to voltage profile, network loss. It was found that the PV generation at the load end undisputedly improves the voltage profile of the grid especially for the load buses which are situated at farther end of the grid. Further, with regard to the overvoltage issue, which is generally a concern during the low load demand period it was concluded that, at a 50% PV penetration level, the voltage level for the load buses is within the limit of 103% as prescribed by the regulator excepting for few load buses. The voltage level for load buses which deviate from the regulatory requirement are located at distance of 1200 meter or further away from the substation. The dynamic impact studied were for voltage unbalancing in the grid, which was found to have greater impact at the load buses which is located farther compared to a bus located nearer to the substation. With respect to impact study related to introduction of harmonics to the grid due to PV system integration, it was found that amount of harmonic content which was measured as total harmonic distortion (THD) multiplies with integration of more number of PV system. For a 50 % penetration level of PV, the introduced harmonics into the representative network is very minimal. Also, it was observed from the simulation study that THD content are be less when the grid operates at low load condition with high solar irradiance compared to lower irradiance and high load condition.

DC to DC converters stabilize the voltage obtained from voltage sources such as solar power system, wind energy sources, wave energy sources, rectified voltage from alternators, and so forth. Hence, the need for improving its control algorithm is inevitable. Many algorithms are applied to DC to DC converters. This thesis designs fuzzy adaptive dynamic programming (Fuzzy ADP) algorithm. Also, this thesis implements both adaptive dynamic programming (ADP) and Fuzzy ADP on DC to DC converters to observe the performance of the output voltage trajectories.

In sustainable energy systems those using fuel cells, high step-up gain converters are widely used to increase the output voltage to levels that can be used by other converters, such as inverters for grid connection or powering other AC loads. In order to obtain a higher voltage gain, in comparison to a traditional boost converter, often different topologies techniques are involved. In this project a new topology is studied, cascading to half bridges, each working similar to a boost converter but with magnetic coupled inductors in-between.    The converter design is modeled in PLECS Blockset and MATLAB Simulink to simulate and evaluate the performance with proper design procedure. The results showed that a high step-up gain was achieved, and the gain could easily be adjusted by changing the duty cycle and/or the coupling factor. The converter design showed similarities and differences to a traditional boost converter. The coupled inductor has its advantage reducing the fuel cell current ripple with the effect of the duty cycle.

The dissertation presents a generalized average-current-mode control technique (GACMC), which is an extension of the average-current-mode control (ACMC) for single-phase ac-dc boost converters with power factor correction (PFC). Traditional ACMC is generalized in a sense that it offers improved performance in the form of significant reduction of the current control loop bandwidth requirement for a given line frequency in unidirectional and bidirectional boost PFC converters, and additional functionality in the form of reactive power control capability in bidirectional converters. These features allow using a relatively low switching frequency and slow-switching power devices such as insulated-gate bipolar transistors (IGBTs) in boost PFC converters, including those designed for higher ac line frequencies such as in aircraft power systems (360–800 Hz). In bidirectional boost PFC converters, including multilevel topologies, the GACMC offers a capability to supply a prescribed amount of reactive power (with leading or lagging current) independently of the dc load power, which allows the converter to be used as a static reactive power compensator in the power system. A closed-loop dynamic model for the current control loop of the boost PFC converter with the ACMC has been developed. The model explains the structure of the converter input admittance, the current phase lead phenomenon, and lays the groundwork for development of the GACMC. The leading phase admittance cancellation (LPAC) principle has been proposed to completely eliminate the current phase lead phenomenon and, consequently, the zero-crossing distortion in unidirectional converters. The LPAC technique has been adapted for active compensation of the input filter capacitor current in bidirectional boost PFC converters. The dynamic model of the current control loop for bidirectional boost PFC converters was augmented to include a reactive power controller. The proposed control strategy enables the converter to process reactive power and, thus, be used as a reactive power compensator, independently of the converter operation as an ac-dc converter. Multiple realizations of the reactive power controller have been identified and examined in a systematic way, along with their merits and limitations, including susceptibility to the ac line noise. Frequency response characteristics of reactive elements emulated by means of these realizations have been described. Theoretical principles and practical solutions developed in this dissertation have been experimentally verified using unidirectional and bidirectional converter prototypes. Experimental results demonstrated validity of the theory and proposed practical implementations of the GACMC. / Ph. D.