No description available.

Hysteresis current control has been widely used in power electronics with the advantages of fast dynamic response under parameter, line and load variation and ensured stability. However, a main disadvantage of hysteresis current control is the uncertain and varying switching frequency which makes it difficult to form an average-value model. The changing switching frequency and unspecified switching duty cycle make conventional average-value models based on PWM control difficult to apply directly to converters that are controlled by hysteresis current control. In this work, a new method for average-value modeling of hysteresis current control in boost converters, three-phase inverters, and brushless dc motor drives is proposed. It incorporates a slew-rate limitation on the inductor current that occurs naturally in the circuit during large system transients. This new method is compared with existing methods in terms of simulation run time and rms error. The performance is evaluated based on a variety of scenarios, and the simulation results are compared with the results of detailed models. The simulation results show that the proposed model represents the detailed model well and is faster and more accurate than existing methods. The slew-rate limitation model of hysteresis current control accurately captures the salient detail of converter performance while maintaining the computational efficiency of average-value models. Validations in hardware are also presented.

Orientador: Falcondes José Mendes de Seixas / Resumo: Os conversores multipulsos têm sido muito utilizados para a melhoria da qualidade de energia elétrica em sistemas de retificação trifásicos. O principal motivo para tal afirmação é a robustez apresentada por esses conversores, aliada às características intrínsecas da estrutura, que resulta no cancelamento natural de certas componentes de corrente na rede, devido ao defasamento angular provocado pela ação do transformador ou autotransformador utilizado. O que se propõe nesse trabalho é a substituição de cada ponte retificadora a diodos, presente no conversor de 12 pulsos, por uma topologia retificadora trifásica semicontrolada, baseada no conversor boost operando no modo de condução descontínuo (MCD), de modo que, seja possível reduzir de maneira significativa a DHTi (Distorção Harmônica Total de corrente), bem como, incorporar os volumosos transformadores de interfase (IPTs) aos indutores boost de alta frequência, resultando na redução de peso e volume. Foram confeccionadas duas versões do conversor de 12 pulsos com retificadores semicontrolados, uma utilizando transformador isolador e a outra um autotransformador. O que se verificou para ambas as configurações é que a estrutura apresenta um reduzido conteúdo harmônico de corrente se comparado ao conversor tradicional e que, ao se operar no modo de condução descontínuo, faz-se possível o emprego de uma lógica de controle simples, possibilitando assim empregar somente uma malha de tensão, e reduzir significativamente a DHTi do... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: Multipulse converters have been widely employed for electrical power quality improvement in three-phase rectifiers systems. The main reason for this statement is the robustness shown by these structures, allied to their natural characteristics, resulting in harmonic canceling at the mains, due to the phase displacement provided by the transformer/autotransformer. In this work, it is proposed the replacement of each rectifier bridge, present in the 12-pulse converter, by a three-phase half-controlled rectifier topology, based on DCM (Discontinuous Conduction Mode) boost converter, thus making it possible to significative reduce the THDi (Total Harmonic Distortion) of the current injected on the mains by the structure. It also incorporates the voluminous IPT's (Interphase Transformer) in the boost high-frequency inductor, resulting in a reduction of weight and size. Two versions of the 12-pulse converter with semicontrolled rectifiers were made, one using an isolating transformer and other using an autotransformer. It was verified that both configurations present a reduced THDi when compared to the traditional converter. So, by electing DCM, it is possible to employ a simpler control logic, employing only one voltage loop and significantly reducing the THDi. / Doutor

La pile à combustible (PàC) est une source d’énergie qui produit de l’électricité à partir de l’hydrogène et de l’oxygène.Elles sont très prometteuses pour la production d'énergie électrique. Néanmoins, la PàC souffre encore d’imperfections limitant ainsi sa commercialisation à grande échelle, tout particulièrement pour les applications de transport.C’est pourquoi, l’hybridation des différentes sources d’énergies est devenue une réalité pour les applications non-stationnaires telles que les véhicules tout électriques.Cependant ces applications nécessitent des solutions de gestion de l’énergie fiables prenant en compte toutes les contraintes du système électrique hybride.Par conséquent, le développement de plateforme de validation est nécessaire.Dans ce contexte, le Hardware In the Loop (HIL) est une technique très prometteuse, où une partie d’un système réel peut être remplacée par un système virtuel tout en respectant la communication entre ces sous-systèmes physiques et virtuels.Ce mémoire détaille des modèles dynamiques d'une pile à combustible échangeuse de proton (PEMFC) hybridée à des supercondensateurs.Par ailleurs, on détaille la gestion d’énergie entre ces deux sources, ainsi que le pronostic de la pile basé d’une part d’un filtre de Kalman étendu (EKF) pour l’estimation de l’état de santé (SoH) réel de la pile, et d’autre part, de la méthode Inverse First Order Reliability Method (IFORM) en vue d’estimer la durée de vie utile restante de la pile, tout cela dans une approche Hardware-In-The-Loop (HIL). / The fuel cell is a source of energy that generates electricity from hydrogen and oxygen.They are very promising candidates for the production of electric power.Nevertheless, the fuel cell still suffers from imperfections limiting its commercialization on a full scale, in particular for transport applications.This is the reason why, hybridization of different energy sources has become a reality for non-stationary applications such as all-electric vehicles.However, these applications require reliable energy management solutions that take into account all the constraints of the hybrid electrical system.Therefore, the development of validation platform is necessary.In this context, the Hardware In the Loop (HIL) is a very promising technique, where part of a real system can be replaced by a virtual system while respecting the communication between these physical and virtual subsystems.This document details the dynamic models of a proton exchange membrane fuel cell (PEMFC) associated with supercapacitors.Furthermore, the energy management between these two sources and the prognostic of the fuel cell composed of a extenced Kalman Filter filter (EKF) for the estimation of the real state of health (SoH) of the stack and, on the other hand, of the Inverse First Order Reliability Method (IFORM) in order to estimate the remaining useful life of the stack, all implemented in an FPGA control board in a Hardware-In-The-Loop (HIL) context.

This thesis examines converter topologies suitable for Module Integrated Converters (MICs) in grid interactive photovoltaic (PV) systems, and makes a contribution to the development of the MIC topologies based on the two-inductor boost converter, which has received less research interest than other well known converters. The thesis provides a detailed analysis of the resonant two-inductor boost converter in the MIC implementations with intermediate constant DC links. Under variable frequency control, this converter is able to operate with a variable DC gain while maintaining the resonant condition. A similar study is also provided for the resonant two-inductor boost converter with the voltage clamp, which aims to increase the output voltage range while reducing the switch voltage stress. An operating point with minimized power loss can be also established under the fixed load condition. Both the hard-switched and the soft-switched current fed two-inductor boost converters are developed for the MIC implementations with unfolding stages. Nondissipative snubbers and a resonant transition gate drive circuit are respectively employed in the two converters to minimize the power loss. The simulation study of a frequency-changer-based two-inductor boost converter is also provided. This converter features a small non-polarised capacitor in a second phase output to provide the power balance in single phase inverter applications. Four magnetic integration solutions for the two-inductor boost converter have also been presented and they are promising in reducing the converter size and power loss.

Energy-efficient radio frequency (RF) power amplifiers (PAs) are critical and paramount to achieve longer battery life in state-of-the-art portable systems because they typically determine and dominate the power consumption of such devices. In this dissertation, a high-efficiency, linear RF PA with a dynamically adaptive supply and bias current control for code division multiple access (CDMA) and wideband CDMA (WCDMA) is conceived, simulated, and experimentally demonstrated with a discrete PCB-level design and in integrated circuit (IC) form. The PA efficiency is improved by dynamically adjusting both its supply voltage and bias current, there by minimizing its quiescent power dissipation. The PA supply voltage is derived from the battery by a noninverting, synchronous buck-boost switching regulator because of its flexible functionality and high efficiency. Adjusting the PA supply voltage and bias current by tracking the output power, instead of following the complete envelope in large baseband bandwidth wireless applications, is achieved by a converter with a lower switching frequency and consequently higher light-load efficiency, which translates to prolonged battery life. A discrete PCB-level prototype of the proposed system with 915 MHz center frequency, CDMA IS-95 signal having 27-dBm peak-output power resulted in more than four times improvement in the average efficiency compared to a fixed-supply class-AB PA while meeting the required performance specifications. In the IC solution fabricated in AMIs 0.5-micron CMOS process through MOSIS, a dual-mode, buck-boost converter with pulse-width modulation (PWM) control for high power and pulse-frequency modulation (PFM) for low power is designed and implemented to improve the PA efficiency during active and standby operation, respectively. The performance of the dynamically adaptive supply and bias control IC was validated by realizing a 25-dBm, 1.96 GHz center frequency, WCDMA PA over an input supply range of 1.4 4.2 V. The PA with dual-mode power supply and bias control IC showed an average-efficiency improvement of seven times compared to a fixed-supply class-AB PA, which translates to five times improvement in battery life assuming the PA is active for 2 % of the total time and in standby mode otherwise.

Στην παρούσα διπλωματική εργασία διερευνώνται οι προδιαγραφές για την εγκατάσταση και τη διασύνδεση με το δίκτυο διανομής ενός οικιακού φωτοβολταϊκού συστήματος. Ο όρος «οικιακό» αναφέρεται σε φωτοβολταϊκά συστήματα μικρής ισχύος, έως 10 kWp, τα οποία τοποθετούνται πάνω σε κτίρια ή ενσωματώνονται σε αυτά ενώ παρέχουν ηλεκτρική ενέργεια στο δίκτυο μέσω της ίδιας παροχής του κτιρίου. Τα οικιακά φωτοβολταϊκά παρουσιάζουν πολλά πλεονεκτήματα ώστε να αποτελέσουν πόλο έλξης για τους μελλοντικούς παραγωγούς όπως θερμική μόνωση, ηχομόνωση, ηλιο-προστασία, δεν απαιτούν επιπλέον χώρο για την εγκατάσταση τους, συνεισφέρουν στην κάλυψη του φορτίου αιχμής, δε περιλαμβάνουν κινητά μέρη, προσφέρουν έναν ελκυστικό σχεδιασμό κτιρίου και αντικαθιστούν συμβατικά κατασκευαστικά υλικά. Στο πρώτο κεφάλαιο παρουσιάζεται μια θεωρητική ανασκόπηση της φύσης της ηλιακής ακτινοβολίας. Στο δεύτερο κεφάλαιο γίνεται μια περιγραφή του ηλιακού κυττάρου, των φωτοβολταϊκών πλαισίων και των αρχών λειτουργίας τους, καθώς και παρουσιάζονται τα ηλεκτρικά χαρακτηριστικά τους και οι παράγοντες που τα επηρεάζουν. Εν συνεχεία, στο τρίτο κεφάλαιο μπορούμε να δούμε τα κριτήρια με τα οποία επιλέγεται ο τόπος και ο τρόπος εγκατάστασης ενός φωτοβολταϊκού συστήματος, και παρουσιάζονται οι αρχές σχεδιασμού του συστήματος ξεκινώντας από την επιλογή του αντιστροφέα μέχρι τα μέσα προστασίας και την καλωδίωση. Στο τέταρτο κεφάλαιο παρουσιάζονται οι απαιτήσεις που πρέπει να τηρούνται ώστε να καθίσταται εφικτή η διασύνδεση με το δίκτυο ΧΤ μιας εγκατάστασης παραγωγής ενέργειας. Επιπλέον, εξετάζονται τα κριτήρια τήρησης των ανωτέρω απαιτήσεων, όπως η επάρκεια του δικτύου, η διαμόρφωση των προστασιών της διασύνδεσης, οι μεταβολές της τάσης, το φαινόμενο flicker, η έγχυση αρμονικών, η νησιδοποίηση και οι επιπτώσεις στα συστήματα Τηλεχειρισμών Ακουστικής Συχνότητας. Εν τέλει, στο πέμπτο κεφάλαιο πραγματοποιούνται προσομοιώσεις για την μελέτη των παραπάνω προδιαγραφών σε δύο διατάξεις που εξομοιώθηκαν με το πρόγραμμα PSCAD. Η μια διάταξη περιλαμβάνει μια φωτοβολταϊκή συστοιχία ισχύος 9.6 kWp, έναν μετατροπέα υποβιβασμού τάσης ο οποίος κάνει την ανίχνευση του σημείου μεγίστης ισχύος, έναν τριφασικό αντιστροφέα με παλμοδότηση SPWM, το φίλτρο LC για τη μείωση του αρμονικού περιεχομένου, έναν μετασχηματιστή απομόνωσης και ανύψωσης τάσης 150V/400V, το δίκτυο ΧΤ και το οικιακό φορτίο. Η δεύτερη διάταξη διαφοροποιείται από την πρώτη στο ότι δεν περιλαμβάνει μετατροπέα υποβιβασμού τάσης, έτσι ο αντιστροφέας αναλαμβάνει την ανίχνευση του σημείου μεγίστης ισχύος. Αρχικά παρουσιάζεται η απόκριση των συστημάτων σε κανονικές συνθήκες λειτουργίας και μέση φόρτιση, ενώ εξετάζεται και η επίδραση των τιμών των ελεγκτών στην απόκριση τους. Στη συνέχεια, γίνεται η μελέτη αρμονικών και η διερεύνηση της επίδρασης της ακτινοβολίας στους συντελεστές ολικής αρμονικής παραμόρφωσης ρεύματος και τάσης, και στο συντελεστή ισχύος. Έπειτα εξετάζεται η απόκριση των συστημάτων σε απότομες μεταβολές της ακτινοβολίας και του φορτίου. Τέλος διερευνώνται οι διακυμάνσεις της τάσης που εμφανίζονται σε οριακές καταστάσεις λειτουργίας του φωτοβολταϊκού και φόρτισης του δικτύου ενώ εξετάζονται και οι επιπτώσεις στα συστήματα Τηλεχειρισμών Ακουστικής Συχνότητας. / The aim of the present thesis is the study of the installation and grid-interconnection requirements and specifications of a domestic photovoltaic system. The term “domestic” refers to low power photovoltaic systems (up to 10 kWp), installed or integrated into buildings while providing electric power to the grid through the buildings main power connection. Domestic photovoltaic systems have a number of advantages, such as thermal / sound insulation, solar protection, they do not require extra space in order to be installed, they can contribute in the case of high power demand, they do not require any moving parts, they can prove attractive in terms of building design and even eventually substitute conventional building materials. These advantages are bound to put them in the center of electric power producers’ attention in the immediate future. In the first chapter a theoretic overview of the nature of solar radiation is presented. In the second chapter, photovoltaic cells and panels as well as their function and electrical properties are briefly analyzed. In the third chapter, the criteria of the photovoltaic system’s installation location and method – from the selection of a proper inverter to the system’s electrical protection equipment and wiring. In the fourth chapter the requirements that must be met in order to establish a connection with the power distribution grid are being presented. The relevant criteria such as: a) power grid adequacy, b) proper design and configuration of the grid connection protection equipment, c) voltage variations, d) flickering, e) voltage/current harmonics, f) islanding, and g) effects on 175Hz remote-operation systems are being studied. Finally, in the fifth chapter, PSCAD-realized simulations with two configurations are presented. The first configuration consists of a 9.6kWp photovoltaic array, a dc-to-dc buck converter which implements a maximum-power-point-tracking algorithm, a SPWM-pulsed three-phase inverter, a LC harmonic filter, an isolating 150V/400Vvoltage transformer, the low-voltage grid and a domestic electric load. The second configuration does not include a buck converter and thus, the maximum-power-point-tracking algorithm is implemented on the inverter. The systems’ response in normal operating conditions and with a medium load as well as the effect of different controller gains in the aforementioned response are initially presented. Afterwards, the system’s voltage/current harmonics and the effect of solar radiation in the Total Harmonic Distortion and Power factors are being studied. In continuation the system’s response in rapid change of solar irradiance / electrical load is presented. Finally, voltage variations which appear in boundary operating conditions of the grid and photovoltaic system, as well as the impact on 175Hz remote-operation systems are studied.

Made available in DSpace on 2014-06-11T19:30:51Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-05-14Bitstream added on 2014-06-13T20:00:55Z : No. of bitstreams: 1 melo_ga_dr_ilha.pdf: 5228605 bytes, checksum: 52731e96bb6ac0861b1e6187109bafa8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / 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... / 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)

Made available in DSpace on 2016-12-12T20:27:37Z (GMT). No. of bitstreams: 1 Joao Cabral.pdf: 4385545 bytes, checksum: c09296f90add051ed37bd87320b15421 (MD5) Previous issue date: 2013-03-06 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / This Master Thesis proposes a high gain non-isolated DC-DC converter applied on the processing of PV energy. The proposed converter is a boost converter with quadratic characteristic and with central point at its output. Basic operations and electric characteristics of a PV cell are described, including the procedures to determine its parameters. A model for numeric simulation is presented. A review of the high gain non-isolated DC-DC converters topologies is presented. Shows the converter´s transfer functions and the control strategy adopted as well as the design of control circuits. The control system is consisting of three loops, an internal loop of input current control, an external loop of total output voltage control and an additional loop of voltage unbalance control. The simulation and experimental results are shown to validate the analysis developed and demonstrate the performance of the control system adopted. / Esta Dissertação de Mestrado propõe um conversor CC-CC não isolado de elevado ganho para aplicação no processamento de energia solar fotovoltaica. O conversor proposto é um boost com característica quadrática e com ponto médio na sua saída. Descrevem-se o funcionamento básico e as características elétricas de uma célula fotovoltaica, incluindo-se o procedimento da determinação dos parâmetros e da modelagem dos módulos fotovoltaicos, apresentando-se um modelo para simulação numérica. Apresenta-se uma revisão de topologias de conversores CC-CC não isolados com elevado ganho estáticos. Apresentam-se as funções de transferência do conversor e a estratégia de controle adotada bem como o projeto dos circuitos de controle. O sistema de controle composto por três malhas de controle, uma malha interna de corrente de entrada, uma malha externa de tensão total e uma malha adicional de equalização de tensão. Resultados de simulação e experimentais são apresentados para validar as análises desenvolvidas e demonstrar o desempenho do sistema de controle adotado.

Orientador: Dr. José L. Azcue Puma / Dissertação (mestrado) - Universidade Federal do ABC, Programa de Pós-Graduação em Engenharia Elétrica, 2016. / Este trabalho apresenta o estudo, modelagem e projeto de um sistema de conversão de energia para a conexão de um módulo fotovoltaico com a rede elétrica. Nesta pesquisa são abordados três conversores para adequar a energia gerada por um painel fotovoltaico e conectá-la à rede elétrica. O primeiro conversor é um Boost intercalado de dois níveis encarregado de implementar o MPPT (Maximum Power Point Tracking), o segundo conversor é um Ressonante LLC que realiza o isolamento galvânico e o terceiro conversor é um inversor em ponte completa que mantém a tensão de barramento em um valor determinado e realiza a conversão de corrente contínua para corrente alternada. Os três conversores são projetados, calculando os elementos passivos que os compõem e simulando os circuitos obtidos. Também, é realizada a modelagem dos conversores e o projeto dos controladores utilizando a análise de pequenos sinais. Os resultados de simulação são apresentados utilizando os softwares PSIM e MATLAB. Na parte experimental são verificados os dois primeiros conversores usando o kit High Voltage Isolated Solar MPPT fabricado pela Texas Instruments. / This work presents the study, modeling and design of a photovoltaic conversion system for the connection of a photovoltaic module with the grid. In this research three converters are approached to adequate the generated energy for a photovoltaic panel and to transfer the energy to the grid. The first converter is an interleaved two-level boost responsible for implementing the MPPT (Maximum Power Point Tracking) the second converter is a Resonant LLC that performs galvanic isolation and the third converter is a complete bridge inverter that keeps the bus voltage at a certain value and performs the conversion of continuos current to alternating current. The three converters are designed, calculating the passive elements that compose them and simulating the obtained circuits. Also, the modeling of the inverters and the design of the controllers are performed using small signal analysis. Simulation results are presented using the PSIM and MATLAB software. In the experimental part the first two inverters are verified using the High Voltage Isolated Solar MPPT kit manufactured by Texas Instruments.