Projeto de um protótipo de um veículo elétrico

Os veículos movidos com combustíveis fósseis são, hoje em dia, os veículos mais utilizados em transportes. Estes meios de transporte caracterizam-se pelo seu baixo rendimento e por serem poluentes, pelo que, nos últimos anos, tem havido um esforço em criar ou melhorar meios de transporte, através do aumento do seu rendimento e eliminando a emissão de poluentes. A utilização de máquinas elétricas como meio de locomoção é uma das soluções alternativas, uma vez que, estas apresentam um rendimento elevado e não emitem diretamente gases tóxicos, apesar das baterias serem uma das principais dificuldades, no que diz respeito à relação peso/densidade de energia. Por outro lado, as baterias, devido à sua capacidade de armazenamento de energia, podem ser utilizadas para armazenar energia da rede elétrica, contribuindo para uma melhor gestão, e também para armazenar num veículo elétrico a energia gerada em modo de travagem e que posteriormente pode ser utilizada para fazer mover o motor elétrico. Neste trabalho fez-se um projeto de um veículo elétrico (VE) e estudou-se o impacto da utilização em massa de veículos elétricos na gestão da rede de energia elétrica. A verificação experimental fez-se com um conversor DC/DC bidirecional com uma configuração em ponte H e com um conversor DC/DC redutor unidirecional. Utilizaram-se compensadores clássicos para, em malha fechada, regular o binário, a velocidade e a corrente, através de compensadores Proporcional Integrativo (PI) e Proporcional Integrativo Derivativo (PID). No desenvolvimento deste projeto, fez-se uma análise teórica, realizaram-se simulações na ferramenta MATLAB/Simulink onde foram criados modelos do veículo elétrico para verificar o seu comportamento, e seguidamente analisaram-se experimentalmente estes resultados. O controlo deste veículo foi feito com a utilização de microcontroladores de baixo custo, recorrendo a uma arquitetura de processamento distribuído/partilhado, constituindo esse estudo uma nova contribuição. Os resultados demonstraram que o rendimento dos veículos elétricos em média encontram-se nos 85-90 %, superior aos atuais 40% dos veículos a combustão interna, eliminando também a emissão de poluentes.

A Construção social do conhecimento :a reorientação curricular via tema gerador na Escola Cabana em Belém/PA

Cette étude analyse l'expérience de réorientation curriculaire atravers le sujet générateur, vécue dans les écoles qui composent le système municipal d'éducation de Belém du Pará - École Cabana, en ayant comme locus de recherche l'École Municipale João Carlos Batista. Ce mouvement de réorientation curriculaire, qui rompt avec le modèle traditionnel d'un curriculum linéaire, hiérarchique et fragmenté a comme préssuposées théoriquesméthodologiques les principes et les catégories freireanas la pédagogie critique qui estime un curriculum interdisciplinaire, dialogique, démocratique et contextuel, à partir de la systématisation d'une proposition theorico-méthodologique de réorientation curriculaire par le thème générateur, c'est-à-dire, en partant de situations-problème de la communauté scolaire, en faisant des relations négociées par les connaissances scolaires pour la compréhension et possible intervention dans la réalité. Cette proposition est mise en oeuvre non seulement à Belém, mais aussi par d autres municipalités du Brésil. Étant donné que l'École Cabana est une expérience inovatrice dans la tentative de viabiliser une Éducation vraiment démocratique, elle dialogue encore avec autres expériences d'écoles de même nature au Brésil, (comme l'École Plural-MG, l'École Citoyen - RS et l'École Candanga DF). Á partir des idées de Paulo Freire, J. Sacristán, M. Apple, C. Linhares, A. Coulon et autres j apporte des réflexions epistemologiques concernant le problème de la recherche qui consiste sur le registre et l'analyse de la tentative de construction sociale de la connaissance par le thème générateur qui a eu lieu à l'École Cabana dans la période de 2001 à 2004. Comme procédure méthodologique, j'ai développé une Recherche qualitative, de caractère collaboratif, en utilisant comme techniques de rassemble de données l observation participative dans le quotidien écolier, des interviews semi-structurées, et l'analyse des documents et des productions de l'École. Les résultats indiquent l'importance du registre de ce type d expérience, en soulignant leurs avances et reculs qui pourront servir de référentiel pour de futures politiques de réorientation curriculaire dans la direction de la construction sociale de la connaissance et, par conséquent, d'une Éducation plus démocratique et tournée vers une citoyenneté active

Técnicas de simplificação de redes e otimização multiobjetivo para análise de variações de tensão em regime permanente provocadas por parques eólicos integrados ao sistema elétrico

This study presents a description of the development model of a representation of simplified grid applied in hybrid load flow for calculation of the voltage variations in a steady-state caused by the wind farm on power system. Also, it proposes an optimal load-flow able to control power factor on connection bar and to minimize the loss. The analysis process on system, led by the wind producer, it has as base given technician supplied by the grid. So, the propose model to the simplification of the grid that allows the necessity of some knowledge only about the data referring the internal network, that is, the part of the network that interests in the analysis. In this way, it is intended to supply forms for the auxiliary in the systematization of the relations between the sector agents. The model for simplified network proposed identifies the internal network, external network and the buses of boulders from a study of vulnerability of the network, attributing them floating liquid powers attributing slack models. It was opted to apply the presented model in Newton-Raphson and a hybrid load flow, composed by The Gauss-Seidel method Zbarra and Summation Power. Finally, presents the results obtained to a developed computational environment of SCILAB and FORTRAN, with their respective analysis and conclusion, comparing them with the ANAREDE

Implementação experimental de filtro ativo paralelo de potência com aplicação a gerador de indução trifásico

This work describes the experimental implementation of a shunt active power filter applied to a three-phase induction generator. The control strategy of active filter turned to the excitation control of the machine and to decrease the harmonics in the generator output current. Involved the implementation of a digital PWM switching, and was made a comparison of two techniques for obtaining the reference currents. The first technique is based on the synchronous dq reference method and the second on the theory of instantaneous power. The comparison is performed via simulation and experimental results. To obtain the experimental results, was mounted a bench trial and the control and communications needed were implemented using DSP - MS320F2812. The simulation results and experimental data proved the efficiency of the filter to apply, highlighting the technique of instantaneous power

Desenvolvimento de Modelos no Programa DigSILENT PowerFactoryTM para o Estudo de Estabilidade Transitória em Sistemas Elétricos de Potência com Aerogerador

This work presents a description of models development at DigSILENT PowerFactoryT M program for the transient stability study in power systems with wind turbine. The main goal is to make available means to use a dynamic simulation program in power systems, widely published, and utilize it as a tool that helps in programs results evaluations used for this intent. The process of simulations and analyses results starts after the models setting description phase. The results obtained by the DigSILENT PowerFactoryT M and ATP, program chosen to the validation also international recognized, are compared during this phase. The main tools and guide lines of PowerFactoryT M program use are presented here, directing these elements to the solution of the approached problem. For the simulation it is used a real system which it will be connected a wind farm. Two different technologies of wind turbines were implemented: doublyfed induction generator with frequency converter, connecting the rotor to the stator and to the grid, and synchronous wind generator with frequency converter, interconnecting the generator to the grid. Besides presenting the basic conceptions of dynamic simulation, it is described the implemented control strategies and models of turbine and converters. The stability of the wind turbine interconnected to grid is analyzed in many operational conditions, resultant of diverse kinds of disturbances

Estudo do efeito de substratos metamateriais em parâmetros de antenas de microfita

Microstrip antennas are subject matter in several research fields due to its numerous advantages. The discovery, at 1999, of a new class of materials called metamaterials - usually composed of metallic elements immersed in a dielectric medium, have attracted the attention of the scientific community, due to its electromagnetic properties, especially the ability to use in planar structures, such as microstrip, without interfering with their traditional geometry. The aim of this paper is to analyze the effects of one and bidimensional metamaterial substrates in microstrip antennas, with different configurations of resonance rings, SRR, in the dielectric layer. Fractal geometry is applied to these rings, in seeking to verify a multiband behavior and to reduce the resonance frequency of the antennas. The results are then given by commercial software Ansoft HFSS, used for precise analysis of the electromagnetic behavior of antennas by Finite Element Method (FEM). To reach it, this essay will first perform a literature study on fractal geometry and its generative process. This paper also presents an analysis of microstrip antennas, with emphasis on addressing different types of substrates as part of its electric and magnetic anisotropic behavior. It s performed too an approach on metamaterials and their unique properties

Desacoplamento de um gerador síncrono através de um controle adaptativo por modelo de referência baseado em funções de Base radial

An alternative nonlinear technique for decoupling and control is presented. This technique is based on a RBF (Radial Basis Functions) neural network and it is applied to the synchronous generator model. The synchronous generator is a coupled system, in other words, a change at one input variable of the system, changes more than one output. The RBF network will perform the decoupling, separating the control of the following outputs variables: the load angle and flux linkage in the field winding. This technique does not require knowledge of the system parameters and, due the nature of radial basis functions, it shows itself stable to parametric uncertainties, disturbances and simpler when it is applied in control. The RBF decoupler is designed in this work for decouple a nonlinear MIMO system with two inputs and two outputs. The weights between hidden and output layer are modified online, using an adaptive law in real time. The adaptive law is developed by Lyapunov s Method. A decoupling adaptive controller uses the errors between system outputs and model outputs, and filtered outputs of the system to produce control signals. The RBF network forces each outputs of generator to behave like reference model. When the RBF approaches adequately control signals, the system decoupling is achieved. A mathematical proof and analysis are showed. Simulations are presented to show the performance and robustness of the RBF network

Estratégia de conversor para interligação de sistemas de geração eólica à rede elétrica

Currently, there are several power converter topologies applied to wind power generation. The converters allow the use of wind turbines operating at variable speed, enabling better use of wind forces. The high performance of the converters is being increasingly demanded, mainly because of the increase in the power generation capacity by wind turbines, which gave rise to various converter topologies, such as parallel or multilevel converters. The use of converters allow effective control of the power injected into the grid, either partially, for the case using partial converter, or total control for the case of using full converter. The back-to-back converter is one of the most used topologies in the market today, due to its simple structure, with few components, contributing to robust and reliable performance. In this work, is presented the implementation of a wind cogeneration system using a permanent magnet synchronous generator (PMSG) associated with a back-to-back power converter is proposed, in order to inject active power in an electric power system. The control strategy of the active power delivered to the grid by cogeneration is based on the philosophy of indirect control

Protótipo de uma unidade com tri-geração de energia para utilizações remotas: aplicação de módulo secondutivo gerador termoelétrico

The generation for termoeletricity is characterized as a solid process of conversion of thermal energy (heat) in electric without the necessity of mobile parts. Although the conversion process is of low efficiency the system presents high degree of trustworthiness and low requisite of maintenance and durability. Its principle is based on the studies of termogeneration carried through by Thomas Seebeck in 1800. The frank development of the technologies of solid state for termoeletricity generation, the necessity of the best exploitation of the energy, also with incentive the cogeneration processes, the reduction of the ambient impact allies to the development of modules semiconductors of high efficiency, converge to the use of the thermoeletric generation through components of solid state in remote applications. The work presents the development, construction and performance evaluation of an prototype, in pilot scale, for energy tri-generation aiming at application in remote areas. The unit is composed of a gas lamp as primary source of energy, a module commercial semiconductor for thermoelectric generation and a shirt for production of the luminosity. The project of the device made compatible a headstock for adaptation in the gas lamp, a hot source for adaptation of the module, an exchanger of to be used heat as cold source and to compose first stage of cogeneration, an exchanger of tubular heat to compose second stage of cogeneration, the elaboration of a converter dc-dc type push pull, adequacy of a system of acquisition of temperature. It was become fullfilled assembly of the prototype in group of benches for tests and assay in the full load condition in order to evaluate its efficiency, had been carried through energy balance of the unit. The prototype presented an electric efficiency of 0,73%, thermal of 56,55%, illumination of 1,35% and global of 58,62%. The developed prototype, as the adopted methodology of assay had also taken care of to the considered objectives, making possible the attainment of conclusive results concerning to the experiment. Optimization in the system of setting of the semicondutor module, improvement in the thermal insulation and design of the prototype and system of protection to the user are suggestions to become it a commercial product

Desenho e Construção de um protótipo gerador de jato de plasma frio a pressão atmosférica para aplicações biomédicas

Research for better performance materials in biomedical applications are constants. Thus recent studies aimed at the development of new techniques for modification of surfaces. The low pressure plasma has been highlighted for its versatility and for being environmentally friendly, achieving good results in the modification of physic chemical properties of materials. However, it is requires an expensive vacuum system and cannot able to generate superficial changes in specific regions. Furthermore, it is limits their use in polymeric materials and sensitive terms due to high process temperatures. Therefore, new techniques capable of generating cold plasma at atmospheric pressure (APPJ) were created. In order to perform surface treatments on biomaterials in specific regions was built a prototype capable of generating a cold plasma jet. The prototype plasma generator consists of a high voltage source, a support arm, sample port and a nozzle through which the ionized argon. The device was formed to a dielectric tube and two electrodes. This work was varied some parameters such as position between electrodes, voltage and electrical frequency to verify the behavior of glow discharges. The disc of titanium was polished and there was a surface modification. The power consumed, length, intensity and surface modifications of titanium were analyzed. The energy consumed during the discharges was observed by the Lissajous figure method. To check the length of the jets was realized with Image Pro Plus software. The modifications of the titanium surfaces were observed by optical microscopy (OM ) and atomic force microscopy (AFM ). The study showed that variations of the parameters such as voltage, frequency and geometric position between the electrodes influence the formation of the plasma jet. It was concluded that the plasma jet near room temperature and atmospheric pressure was able to cause modifications in titanium surface

A química no ensino médio e a contextualização: a fabricação dos sabões e detergentes como tema gerador de ensino aprendizagem

El conocimiento químico es muy importante a la comprensión de procesos físicos y químicos que nos acercan, por una opción de una vida mejor con calidad, fomentando y acompañando el desarrollo tecnológico. Sin embargo, la formación de un pensamiento químico fruto de un aprendizaje significativo es hoy, en todo el país, un reto paro los educadores de química. Estúdios señalan la contextualización de los contenidos químicos como recurso para promover una interrelación entre conocimientos escolares y hechos/situaciones presentes en el cotidaiano de los alumnos, añadiendo significado a los contenidos escolares, proporcionando a los alumnos un aprendizaje significativo. Con tal objetivo, la siguiente pesquisa se realizó con la intención de contribuir con la enseñanza de química y con el propósito general de proponer un materila didáctico que presentase una forma contextualizada de trabajar algunos conceptos y contenidos fundamentales a la química, con tema generador de la enseãnaza y aprendizaje a la fabricación de jabones y detergentes. Con objetivo de justificar la elección del planteamiento de la contextualización y la elaboración del material didáctico, se hizo una pesquisa acerca de la enseãnaza de química en al red pública de educación y la relación de ésta con los contextos pertenecentes a la realidad de los alumnos. Se observó que la enseñanza de química actual en la red pública de educación es tradicional y descontextualizada. Los resultados de esta pesquisa muestran la necesidad de cámbios la forma de como se enseñan los contenidos químicos. En la segunda parte de la pesquisa, se produjo la elaboración de la unidad didáctica de enseñanza, con el objetivo de promover el aprendizaje significativo de conocimientos químicos a partir del tema de la fabricación de jabones y detergentes. Se observó que el trabajo alcanzó los objetivos propuestos. Una evaluación cualitativa mostró que los alumnos estuvieron más participativos e interesados al estudiar química de esta forma. Relatos y decalraciones de los alumnos también indicaron que hubo un aprendizaje significativo de los contenidos trabajados y que los alumnos son capaces de transferirlos para la comprensión de situaciones reales. Y una evaluación cuantitativa del material nos reveló que 87,09% de los alumnos obtuvieron apuntes iguales o superiores a la media necesaria para la aprobación. Esperamos que hayamos contribuído para mejorar la calidad de la enseñanaza de química y que este trabajo sea solamente un comienzo de una gran jornada