CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / Universidade Federal do Cearà / Atualmente, existem no mercado internacional vÃrios fabricantes de conversores estÃticos para infraestrutura fotovoltaica. No Brasil, por praticamente nÃo existir um produto com tecnologia nacional que atinja este nicho de mercado, à importante e urgente o desenvolvimento de tecnologia nacional na Ãrea de conversores para sistemas fotovoltaicos. O presente trabalho consiste no desenvolvimento de um conversor CC-CA trifÃsico com a finalidade de interligar um sistema fotovoltaico com a rede elÃtrica, onde o objetivo principal deste sistema à fornecer potÃncia ativa para o sistema elÃtrico trifÃsico. Este conversor CC-CA trifÃsico à composto por um estÃgio de conversÃo CC-CC, o qual consiste em um conversor do tipo elevador (Boost), e um estÃgio de conversÃo CC-CA. A escolha da topologia do conversor considerou alguns critÃrios, tais como baixo custo de aquisiÃÃo e de manutenÃÃo, baixa complexidade e elevado grau de compactaÃÃo e de confiabilidade. A modelagem e o controle do conversor sÃo feitos vetorialmente, ou seja, utilizando as transformadas dq0 direta e inversa. Este controle foi implementado em um controlador digital sinais (DSC) da famÃlia dsPIC. O projeto dos controladores de ambos os estÃgios foi feito de forma digital. Por meio da simulaÃÃo foi validado o funcionamento do conversor e de seus controladores projetados. Para a realizaÃÃo dos testes experimentais algumas modificaÃÃes de projeto tiveram que ser efetuadas, pois se verificou uma quantidade significativa de interferÃncia eletromagnÃtica e ruÃdos gerados pelo protÃtipo durante o seu funcionamento. Dentro das condiÃÃes estabelecidas foi possÃvel injetar na rede elÃtrica uma potÃncia em torno de 40% do valor mÃximo especificado. Os resultados experimentais obtidos a partir do protÃtipo montado em laboratÃrio validaram o algoritmo de controle implementado no conversor, sendo injetadas na rede elÃtrica correntes senoidais com baixo conteÃdo harmÃnico e na frequÃncia do sistema elÃtrico brasileiro. / Currently, there are several manufacturers in the international market of static converters for photovoltaic infrastructure. In Brazil, by there is no product with a national technology to reach this niche market, is important and urgent to develop national technology in the field of DC-AC converters to PV systems. The present work consists of developing of a three-phase AC-DC converter with the purpose of connect a PV system to the electricity grid, where the main objective of this system is to provide active power for the three-phase electrical system. This three-phase AC-DC converter is composed of a stage of DC-DC conversion, which consists in a boost converter, and a stage of DC-AC conversion. The choice of converter topology considered some criteria, such as low cost of acquisition and maintenance, low complexity, high compaction and reliability. The modeling and control of the converter are made using the concept of space vector, in the other words, using the dq0 transform direct and inverse. This control was performed in a digital signal controller (DSC) of dsPIC family. The design of the controllers of both stages was done digitally. Through simulation was validated the operation of the converter and its controllers designed. For the experimental tests some design changes had to be made because there was a significant amount of electromagnetic interference and noise generated by the prototype during its operation. From the conditions established was possible to inject into the electricity grid a just over 40% of the maximum value of power specified. The experimental results from the prototype validated the control algorithm implemented in the converter, being injected into the electricity grid sinusoidal currents with low harmonic content and frequency of the brazilian electrical system.

Orientador: Jose Raimundo de Oliveira / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Eletrica e de Computação / Made available in DSpace on 2018-08-09T17:11:57Z (GMT). No. of bitstreams: 1 Campos_TatianeJesusde_D.pdf: 4875626 bytes, checksum: 36e6cf7484aa1c689c28b67404d977e5 (MD5) Previous issue date: 2007 / Resumo: Na última década os algoritmos evolutivos vem sendo aplicados na síntese e projeto de circuitos eletrônicos criando uma nova área de pesquisa denominada Hardware Evolutivo. Esta tese propõe o uso de Hardware Evolutivo como uma ferramenta para geração automática de circuitos aplicados ao controle de um pêndulo amortecido não linear. Inicialmente um amplo estudo sobre a utilização de computação evolutiva aplicada à síntese de circuitos eletrônicos foi realizado, de modo a identificar os principais benefícios, motivações, aplicações e desafios da área de Hardware Evolutivo. A seguir foi realizado um estudo de caso com o objetivo de realizar uma comparação experimental dos principais pontos que afetam o desempenho de um sistema de Hardware Evolutivo na evolução de circuitos digitais básicos. Após a realização destas etapas foi desenvolvido um Hardware Evolutivo para controle de um pêndulo não linear. O objetivo desta implementação foi apresentar comparações de desempenho entre diferentes abordagens para projetos de controladores. O uso do Hardware Evolutivo para obtenção do controlador tem como objetivo modelar o comportamento não linear do sistema e sintetizá-lo em um circuito digital combinacional criando assim uma alternativa de projeto automático para sistemas de controle. A análise e simulação do pêndulo não linear demonstra que a aplicação desta nova técnica de projeto de hardware apresenta resultados promissores / Abstract: In the last decade evolutionary algorithms application in electronic circuits synthesis have been intensively investigated, starting a new research area called Evolvable Hardware. This thesis considers the use of Evolvable Hardware as a tool for automatic design of circuits applied to the control of a nonlinear damped pendulum. Initially a study on the use of applied evolutionary algorithms to the synthesis of electronic circuits was carried out, in order to identify the main benefits, motivations, applications and challenges of the field of Evolvable Hardware. A case study was carried out with the objective to provide an experimental comparison of the main points that affect the performance of a system in the evolution of basic digital circuits. Finally a Evolvable Hardware controller unit for control a nonlinear damped pendulum was evolved. The objective of this implementation was to present performance comparisons between two different controllers designs. The analysis and simulation of nonlinear pendulum demonstrate that the application of this new technique of design provides excellent results / Doutorado / Engenharia de Computação / Doutor em Engenharia Elétrica

De maneira geral, a necessidade de aumentar o desempenho e diminuir o tamanho dos sistemas mecatrônicos tem levado a indústria moderna a idealizar e desenvolver sistemas de posicionamento com boas características de aceleração e precisão de posicionamento. Por outro lado, a crescente demanda de componentes com melhores características metrológicas e de acabamento, tais corno lentes para raio X e infra vermelho, tem exigido o desenvolvimento de variados tipos de sistemas de microposicionamento capazes de movimentar elementos de máquinas em distâncias muito pequenas com alto grau de exatidão, dentre os quais podem-se destacar os acionados por meio de atuadores piezoelétricos. Este trabalho propõe a utilização de um novo tipo de atuador baseado na propriedade de estricção eletromagnética de certas ligas metálicas (atuadores magnetoestritivos) associado a um sistema de controle digital que utiliza um algoritmo de controle baseado em lógica difusa e redes neurais artificiais para o controle de microposicionamento. Metodologias e princípios de projeto para engenharia de precisão são abordados de forma a auxiliar no desenvolvimento de dois protótipos de posicionadores para uso em usinagem de ultraprecisão. Resultados obtidos em testes experimentais apontam para urna melhoria no comportamento dinâmico dos microposicionadores acionados por atuadores magnetoestritivos. Isto permite sua utilização como alternativa válida no posicionamento submicrométrico. / In general, actual requirements such as high performance and small sizes of mechatronic systems, has led modern industry to design positioning systems with good characteristics of acceleration and positioning accuracy. The increasing demand of components with better metrological and finish characteristics, as X-ray and infra-red lens, has allowed the development of a number of types of micropositioning systems that are able to move machine elements to very small distances with high levels of accuracy. In this work it is proposed the use of a new type of actuator that applies the properties of electromagnetic strain of certain metallic alloys (magnetostrictive actuators). lt is also proposed the application of a digital control system that uses a control algorithm which is based on fuzzy logic and artificial neural networks for the micropositioning control. Design principles and methodologies related to precision engineering are discussed with the purpose of aiding the development of two prototypes of positioners for ultraprecision rnachining, experimental results show that micropositioner driven by magnetostrictive actuators have better dynamics behaviours. This allows the use of such actuators as an valid alternative for positioning in submicrometer range.

This thesis describes research and development. work carried out by the author into the control of traction and braking systems on rail vehicles. After a review of recent developments, the problem of. driving a train under minimum-energy control subject·to timetable and operational constraints is discussed. This is partitioned into two sections. Firstly, target time and velocities for key pOints on the journey are computed; these are communicated to or stored on the train, together with route and vehicle data. Secondly, an on-board digital system drives the train to each target according to control algorithms which incorporate a predictorcorrector module, whose function is to determine which of two criteria of performance is to be used (minimum-energy when running early or on-time, minimum-time when running late). Most of the thesis is devoted to the analysis and design of the train-borne control system. The general form of the optimal control (of tractive or braking effort) is determined by the application of Pontryagin's Maximum Principle over each section of the journey. However, the moments of transition between the various modes of control are calculated by a method which involves a lookahead model in the predictor module, rather than by iterative solution of the state and co-state equations . An important aspect of the design is the dynamic response of the braking SUb-system, which may include a substantial pneumatic transport lag within the control loop. S-plane and z-plane design procedures for the required discrete control algorithms to.achieve a specified transient response are derived. The thesis concludes with a chapter on the instrumentation required for the train-borne control system.

This diploma thesis deals with analysis and exploration of design options, how to design and produce an electronic load. The paper discussed the possibilities of digital control. It also describes the principles of structural components and there was chosen one type variant which is designed to circuits and printed circuit boards. Moreover, the thesis also include technical drawings of mechanical parts. At the end of this paper, final soulution with measurements and parameters are presented.

The paper presents design solution and physical implementation of a system for examination of electro hydraulic steering based on OSPE 200 components. The implementation is based on synthesis of required hydraulic and structure parameters, presented in a previous paper. Now we present the interconnection of the digital control system and the closed-loop flow diagram. A formal description of embedded software is presented too, which supports operation of PI control algorithm in real-time. Identification is performed based on experimentally reported the transitional process by developing mathematical models. Presents the structure and capabilities of the models for identification, as well as procedures for their validation.

Lighting consumes approximately 20-25% of the energy produced worldwide. LED based lighting is rapidly becoming the preferred choice over incandescent and fluorescent based lighting. LEDs have advantages such as high efficacy, long operating lifetime and excellent lumen maintenance. Therefore, to gain benefits from LEDs for lighting purposes, they must be driven with efficient drivers which maintain high LED efficacy and long LED lifetime. A review of existing LED drivers is done, and their advantages and drawbacks are identified. Existing fault-tolerant drivers are also reviewed. Several dimming methods and their effects on the LED efficacy and lifetime are investigated. As a result, a converter with coupled inductors, suitable as an LED driver which has high efficiency and can maintain high LED efficacy, incorporated with a high efficiency dimming method, is chosen. For the proposed LED driver, a comprehensive analysis on the effects of coupling type and coupling coefficient on converter performance is done. This is carried out to establish the best coupled inductor structure and coupling coefficient, for the proposed LED driver. The coupled inductor obtained is used to achieve high LED efficacy and also used to eliminate the need for an output filtering capacitor. This results in a highly compact, high efficiency and low cost LED driver. A lossless method of LED string current sensing is proposed, so that driver efficiency is not negatively impacted. The LED driver and a digital control system are designed, with the fault-tolerant feature incorporated. The LED driver and the control system are simulated and practically implemented. The results obtained show excellent LED driver performance. The fault-tolerant feature can enable the driver to operate under fault conditions, saving repair costs and down time. Additionally, a novel digitally controlled LED driver, which can drive several independent multiple LED loads, is proposed. This novel driver is simulated and practically implemented; with the results showing excellent driver performance. The novel LED driver can simplify and reduce costs of existing LED lighting systems. / Dissertation (MEng)--University of Pretoria, 2013. / gm2014 / Electrical, Electronic and Computer Engineering / Unrestricted

Iterative Learning Control (ILC) considers systems which perform the given desired trajectory repetitively. The command for the upcoming iteration is updated after every iteration based on the previous recorded error, aiming to converge to zero error in the real-world. Iterative Learning Control can be considered as an inverse problem, solving for the needed input that produces the desired output. However, digital control systems need to convert differential equations to digital form. For a majority of real world systems this introduces one or more zeros of the system z-transfer function outside the unit circle making the inverse system unstable. The resulting control input that produces zero error at the sample times following the desired trajectory is unstable, growing exponentially in magnitude each time step. The tracking error between time steps is also growing exponentially defeating the intended objective of zero tracking error. One way to address the instability in the inverse of non-minimum phase systems is to use basis functions. Besides addressing the unstable inverse issue, using basis functions also has several other advantages. First, it significantly reduces the computation burden in solving for the input command, as the number of basis functions chosen is usually much smaller than the number of time steps in one iteration. Second, it allows the designer to choose the frequency to cut off the learning process, which provides stability robustness to unmodelled high frequency dynamics eliminating the need to otherwise include a low-pass filter. In addition, choosing basis functions intelligently can lead to fast convergence of the learning process. All these benefits come at the expense of no longer asking for zero tracking error, but only aiming to correct the tracking error in the span of the chosen basis functions. Two kinds of matched basis functions are presented in this dissertation, frequency-response based basis functions and singular vector basis functions, respectively. In addition, basis functions are developed to directly capture the system transients that result from initial conditions and hence are not associated with forcing functions. The newly developed transient basis functions are particularly helpful in reducing the level of tracking error and constraining the magnitude of input control when the desired trajectory does not have a smooth start-up, corresponding to a smooth transition from the system state before the initial time, and the system state immediately after time zero on the desired trajectory. Another topic that has been investigated is the error accumulation in the unaddressed part of the output space, the part not covered by the span of the output basis functions, under different model conditions. It has been both proved mathematically and validated by numerical experiments that the error in the unaddressed space will remain constant when using an error-free model, and the unaddressed error will demonstrate a process of accumulation and finally converge to a constant level in the presence of model error. The same phenomenon is shown to apply when using unmatched basis functions. There will be unaddressed error accumulation even in the absence of model error, suggesting that matched basis functions should be used whenever possible. Another way to address the often unstable nature of the inverse of non-minimum phase systems is to use the in-house developed stable inverse theory Longman JiLLL, which can also be incorporated into other control algorithms including One-Step Ahead Control and Indirect Adaptive Control in addition to Iterative Learning Control. Using this stable inverse theory, One-Step Ahead Control has been generalized to apply to systems whose discrete-time inverses are unstable. The generalized one-step ahead control can be viewed as a Model Predictive Control that achieves zero tracking error with a control input bounded by the actuator constraints. In situations where one feels not confident about the system model, adaptive control can be applied to update the model parameters while achieving zero tracking error.

Solar power is becoming ever more popular in a variety of applications. It is particularly attractive because of its abundance, renewability, and environment friendliness. Solar powered spacecraft systems have ever-expanding loads with stringent power regulation specifications. Moreover, they require a light and compact design of their power system. These constraints make the optimization of power harvest from solar arrays a critical task. Florida Power Electronics Center (FPEC) at UCF set to develop a modular fault-tolerant power system architecture for space applications. This architecture provides a number of very attractive features including Maximum Power Point Tracking (MPPT) and uniform power stress distribution across the system. MPPT is a control technique that leads the system to operate its solar sources at the point where they provide maximum power. This point constantly moves following changes in ambient operating conditions. A digital controller is setup to locate it in real time while optimizing other operating parameters. This control scheme can increase the energy yield of the system by up to 45%, and thus significantly reduces the size and weight of the designed system. The modularity of the system makes it easy to prototype and expand. It boosts its reliability and allows on-line reconfiguration and maintenance, thus reducing down-time upon faults. This thesis targets the analysis and optimization of this architecture. A new modeling technique is introduced for MPPT in practical environments, and a novel digital power stress distribution scheme is proposed in order to properly distribute peak and thermal stress and improve reliability. A 2kW four-channel prototype of the system was built and tested. Experimental results confirm the theoretical improvements, and promise great success in the field.

This dissertation investigates digital controller and switch mode power supply design for super high-speed permanent magnet synchronous motors (PMSM). The PMSMs are a key component for the miniaturic cryocooler that is currently under development at the University of Central Florida with support from NASA Kennedy Space Center and the Florida Solar Energy Center. Advanced motor design methods, control strategies, and rapid progress in semiconductor technology enables production of a highly efficient digital controller. However, there are still challenges for such super high-speed controller design because of its stability, high-speed, variable speed operation, and required efficiency over a wide speed range. Currently, limited research, and no commercial experimental analysis, is available concerning such motors and their control system design. The stability of a super high-speed PMSM is an important issue particularly for open-loop control, given that PMSM are unstable after exceeding a certain applied frequency. In this dissertation, the stability of super high-speed PMSM is analyzed and some design suggestions are given to maximize this parameter. For ordinary motors, the V/f control curve is a straight line with a boost voltage because the stator resistance is negligible and only has a significant effect around the DC frequency. However, for the proposed super high-speed PMSM the situation is quite different because of the motor's size. The stator resistance is quite large compared with the stator reactive impedance and cannot be neglected when employing constant a V/f control method. The challenge is to design an optimal constant V/f control scheme to raise efficiency with constant V/f control. In the development, test systems and prototype boards were built and experimental results confirmed the effectiveness of the dissertation system.