Η παρούσα εργασία πραγματεύεται αφ’ενός μεν τη μελέτη, μέσω προσομοίωσης, ενός αιολικού συστήματος παραγωγής ηλεκτρικής ενέργειας συνδεδεμένο στο δίκτυο χαμηλής τάσης αφ’ετέρου δε την κατασκευή ενός τμήματος του συστήματος αυτού. Το αιολικό σύστημα συγκροτείται από μία ανεμογεννήτρια με σύγχρονη γεννήτρια μόνιμων μαγνητών και διατάξεις ηλεκτρονικών ισχύος που μετατρέπουν αρχικά την εναλλασσόμενη τάση σε συνεχή και στη συνέχεια τη συνεχή τάση σε εναλλασσόμενη, συχνότητας 50Hz, για τη σύνδεση με το δίκτυο. Πιο συγκεκριμένα, χρησιμοποιούνται κατά σειρά μία μη ελεγχόμενη ανορθωτική γέφυρα με διόδους για την ανόρθωση της τάσης, που παράγεται από τη γεννήτρια, ένας μετατροπέας τύπου Boost για την ανύψωση και σταθεροποίηση της τάσης και τέλος, ένας μονοφασικός αντιστροφέας με MOSFET. Η έξοδος του αντιστροφέα, μέσω φίλτρου και μετασχηματιστή, συνδέεται στο δίκτυο. Στόχος είναι η κατασκευή ενός πειραματικού πρωτοτύπου για τη σύνδεση της ανεμογεννήτριας του εργαστηρίου, ισχύος 1kW, με το δίχτυο χαμηλής τάσης, ώστε να χρησιμοποιηθεί για εργαστηριακούς και ερευνητικούς σκοπούς. / This thesis presents the study, modeling and implementation of a wind power system consists of a permanent magnet synchronous generator, a rectifier and boost stage, as well as an inverter stage for grid connection. Control applies on the dc-dc converter aiming at rendering the connection to the electrical power grid more versatile. The analysis was performed by developing an appropriate model for the system at the Matlab computing program aided by the Simulink toolbox of The MathWorks,Inc.

Σκοπός της παρούσας διπλωματικής εργασίας είναι η προστασία ενός μικροδικτύου συνδεδεμένου στο δίκτυο διανομής χαμηλής τάσης από μεγάλα ρεύματα που οφείλονται σε βυθίσεις τάσης του δικτύου διανομής. Η μελέτη θα περιλαμβάνει όλα εκείνα τα στοιχεία που είναι απαραίτητα για τη σύνδεση σε ένα δίκτυο. Συγκεκριμένα, θα περιλαμβάνει τον ανυψωτή τάσης (boost converter) ο οποίος είναι υπεύθυνος για την ανύψωση της συνεχούς τάσης εξόδου της διεσπαρμένης παραγωγής, τον αντιστροφέα (inverter) ο οποίος θα μετατρέπει την συνεχή τάση εξόδου του ανυψωτή σε εναλλασσόμενη με το επιθυμητό πλάτος κ συχνότητα, και τέλος θα περιλαμβάνει το σύστημα ελέγχου το οποίο θα προσπαθεί να ικανοποιεί τις ενεργειακές ανάγκες κάθε φορτίου ρυθμίζοντας κατάλληλα τις παραμέτρους των προηγούμενων μερών. Επιπλέον σε περιπτώσεις βύθισης τάσης η διπλωματική εργασία προτείνει μία μέθοδο ελέγχου η οποία προσπαθεί να άρει την διανυσματική πτώση τάσης στην γραμμή διασύνδεσης μικροδικτύου και δικτύου διανομής. Επειδή η μελέτη ενός τέτοιου πραγματικού συστήματος δεν ήταν εφικτή στα πλαίσια μας διπλωματικής εργασίας, επιλέχθηκε η μέθοδος εξομοίωσης σε ηλεκτρονικό υπολογιστή. Για την εξομοίωση χρησιμοποιήθηκε το πρόγραμμα PSCAD,ένα από τα πλέον καταλληλότερα προγράμματα για την μελέτη των συστημάτων ηλεκτρικής ενέργειας. Η επιλογή του PDCAD στηρίχθηκε στο γεγονός ότι είναι εξαιρετικά εύχρηστο ενώ ταυτόχρονα έχει γρήγορες αποκρίσεις και χρησιμοποιείται κατά κόρον για την προσομοίωση τέτοιων συστημάτων. / The purpose of this diplomathesis is to protect a microgrid, which is connected to low voltage distribution network, of large currents due to voltage sags in the distribution network. This study includes all the elements needed to connect the microgrid to a network. Specifically, it includes the boost converter which is responsible for raising the voltage output of dispersed production, the inverter which will convert the voltage output of the enhancer into alternating with the desired width and frequency and at last it includes the control system which tries to satisfy the energy needs of each load by adjusting appropriate parameters of the previous parameters. Moreover, in cases of voltage sags, this diploma thesis proposes a control method that attempts to eliminate the vector voltage drop in interconnection microgrid and distribution network. Since the study of such a real system was not feasible in our thesis, the method was chosen to be simulated in a computer. The simulation program that was used is the PSCAD, one of the most appropriate programs for the study of electric power systems. The choice of PSCAD relied on the fact that it is extremely handy, with fast responses and is widely used for simulating such systems.

COSTA, M. V. S. Controle MPC robusto aplicado ao conversor Boost CCTE otimizado por inequações matriciais lineares. 2017. 178 f. Tese (Doutorado em Engenharia Elétrica)–Centro de Tecnologia, Universidade Federal do Ceará, Fortaleza, 2017. / Submitted by Marlene Sousa (mmarlene@ufc.br) on 2017-09-06T17:10:36Z No. of bitstreams: 1 2017_tese_mvscosta.pdf: 5929867 bytes, checksum: 81ddf2f8352a8740c1bfba2216f43bfa (MD5) / Approved for entry into archive by Marlene Sousa (mmarlene@ufc.br) on 2017-09-06T17:11:16Z (GMT) No. of bitstreams: 1 2017_tese_mvscosta.pdf: 5929867 bytes, checksum: 81ddf2f8352a8740c1bfba2216f43bfa (MD5) / Made available in DSpace on 2017-09-06T17:11:16Z (GMT). No. of bitstreams: 1 2017_tese_mvscosta.pdf: 5929867 bytes, checksum: 81ddf2f8352a8740c1bfba2216f43bfa (MD5) Previous issue date: 2017-07-21 / This work proposes a MPC predictive control strategy applied to a three-state switching cell boost (3SSC) converter that gives more simplicity and systematization to the control design steps and analysis. The integral gain controller can adjusted, eliminating the re-design the weighting matrices. Besides, the stability elipsoid theory are used to simplify the stability analysis of converter. The proposed MPC begins using the linear time varying (LTV) model plant. The parameters variations are considered polytopic uncertainties using linear matrix inequalities approach (LMIs) with relaxations. Theoretical and experimental aspects are applied and analyzed to a 1 kW 3SSC boost converter with voltage input and load uncertainties. To 500 W experimental test, it is considered load and voltage input steps variations. To 1000 W experimental test, it is only considered load steps variation. Also, the proposed MPC-LMI is compared with a classical LQI known in the literature. Theoretical-experimental aspects are applied and analyzed in a 1 kW converter with uncertainties in the input voltage and load. For the experiments, the voltage and load step tests for the 500 W project and a load step test for the 1000 W one were considered. In addition, to establish a performance reference, the proposed MPC is compared with the classic LQR controller known in the literature. The proposed control strategy presents advantages considering the variations of the model due to load tests in DC-DC 3SSC boost applications, being a feasible proposal in solving problems for high-performance converters. / Este trabalho propõe uma estratégia de controle preditivo MPC aplicado a um conversor boost com célula de comutação em 3 estados (CCTE) que confere mais simplicidade e sistematização nas fases de projeto e análise do controlador. O ganho integral do controlador pode ser ajustável, dispensando o reprojeto nas matrizes de ponderação. Para simplificar a análise de estabilidade do controlador, utiliza-se o conceito de elipsóides de estabilidade. O controle MPC proposto parte da modelagem da planta no espaço de estados médio linear e variante no tempo (LTV). As variações paramétricas, no contexto deste trabalho, são tratadas como incertezas politópicas expressas por meio de desigualdades matriciais lineares (LMIs) com relaxações. Aspectos teórico-experimentais são aplicados e analisados em um conversor boost CCTE de 1 kW com incertezas na tensão de entrada e na carga. Para os ensaios, são considerados os testes de degrau de tensão e de carga para o projeto em 500 W e para o degrau de carga com operação em 1000 W . Além disso, para estabelecer uma base de desempenho, o MPC proposto é comparado com o controlador LQI clássico conhecido na literatura. A estratégia de controle proposta apresenta vantagens considerando as variações do modelo decorrente dos testes de cargas em aplicações boost CC-CC do tipo CCTE, sendo uma proposta viável na solução de problemas em conversores de alto rendimento.

abstract: A novel integrated constant current LED driver design on a single chip is developed in this dissertation. The entire design consists of two sections. The first section is a DC-DC switching regulator (boost regulator) as the frontend power supply; the second section is the constant current LED driver system. In the first section, a pulse width modulated (PWM) peak current mode boost regulator is utilized. The overall boost regulator system and its related sub-cells are explained. Among them, an original error amplifier design, a current sensing circuit and slope compensation circuit are presented. In the second section – the focus of this dissertation – a highly accurate constant current LED driver system design is unveiled. The detailed description of this highly accurate LED driver system and its related sub-cells are presented. A hybrid PWM and linear current modulation scheme to adjust the LED driver output currents is explained. The novel design ideas to improve the LED current accuracy and channel-to-channel output current mismatch are also explained in detail. These ideas include a novel LED driver system architecture utilizing 1) a dynamic current mirror structure and 2) a closed loop structure to keep the feedback loop of the LED driver active all the time during both PWM on-duty and PWM off-duty periods. Inside the LED driver structure, the driving amplifier with a novel slew rate enhancement circuit to dramatically accelerate its response time is also presented. / Dissertation/Thesis / Doctoral Dissertation Electrical Engineering 2016

Made available in DSpace on 2014-06-11T19:22:32Z (GMT). No. of bitstreams: 0 Previous issue date: 2011-12-15Bitstream added on 2014-06-13T18:49:30Z : No. of bitstreams: 1 silva_lsc_me_ilha.pdf: 2144752 bytes, checksum: 39f1f729cd628eedd60a6b582fefd576 (MD5) / Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq) / Este trabalho propõe um conversor CA-CC, modulado por largura de pulso (PWM), de elevado fator de potência, dotado de um controle variável da razão cíclica. O estágio de potência do conversor pré-regulador do fator de potência (PFP) proposto é composto por múltiplas células entrelaçadas. A integração das técnicas de entrelaçamento (interleaving) à técnica de eliminação da ponte retificadora da entrada (bridgeless) busca diminuir as perdas de energia e distribuir os esforços de corrente nos semicondutores da estrutura conversora de potência. O levantamento bibliográfico foi realizado com intuito de analisar resultados e características de conversores CA-CC baseados em estruturas PFP boost modificadas. Comparações foram realizadas levando em consideração as características de distorção harmônica, fator de potência, complexidade do circuito de controle, eficiência energética, esforços nos semicondutores de potência e emissão de interferência eletromagnética (IEM). O conversor proposto é então equacionado e os valores dos componentes acumuladores de energia determinados são escritos como função das especificações de projeto. Análises gráficas indicam o comportamento da distorção harmônica e do fator de potência da estrutura atuando em diferentes níveis de tensão. Simulações são realizadas como forma de comprovar a eficácia do sistema conversor no que se refere à correção do fator de potência e à distribuição dos esforços nos semicondutores de potência. Os principais resultados estão dispostos em tabelas comparativas, que indicam um fator de potência praticamente unitário. O sistema de regulação da tensão saída, testado via simulação computacional, apresenta resultados que demonstram boa dinâmica na resposta transitória e erro nulo a regime frente às variações de carga e afundamentos na... / This paper proposes an AC-DC converter, pulse width modulated (PWM) with high power factor and a variable duty cycle control. The power factor preregulator (PFP) converter proposed is composed of multiple bridgeless boost interleaved cells. The integration of these techniques allows a reduction in the energy losses and sharing the stress in power semiconductors. The literature review was performed in order to analyze the results and characteristics of AC-DC converters based on modified PFC boost structures. Comparisons were made taking into account the characteristics of harmonic distortion, power factor, complexity of control circuitry, energy efficiency, current stress in power semiconductors, and emission of electromagnetic interference (EMI). The proposed converter is mathematically equated and the values of the reactive components are written as a function of design specifications. Graphical analysis indicates the behavior of harmonic distortion and power factor of the structure at different voltage levels. Simulations are performed in order to demonstrate compliance of the converter system with respect to the power factor correction and distribution efforts in the power semiconductors. The main results are arranged in comparative tables which indicate power factor very closed to unity. The control system applied to the converter was evaluated through the computer simulations which showed good dynamics at transient response and null steady-state error faced to load variations and sags in the voltage supply. The prototype for the power stage implemented in the laboratory operated according... (Complete abstract click electronic access below)

Renewable or sustainable energy (SE) sources have attracted the attention of many countries because the power generated is environmentally friendly, and the sources are not subject to the instability of price and availability. This dissertation presents new trends in the DC-AC converters (inverters) used in renewable energy sources, particularly for photovoltaic (PV) energy systems. A review of the existing technologies is performed for both single-phase and three-phase systems, and the pros and cons of the best candidates are investigated. In many modern energy conversion systems, a DC voltage, which is provided from a SE source or energy storage device, must be boosted and converted to an AC voltage with a fixed amplitude and frequency. A novel switching pattern based on the concept of the conventional space-vector pulse-width-modulated (SVPWM) technique is developed for single-stage, boost-inverters using the topology of current source inverters (CSI). The six main switching states, and two zeros, with three switches conducting at any given instant in conventional SVPWM techniques are modified herein into three charging states and six discharging states with only two switches conducting at any given instant. The charging states are necessary in order to boost the DC input voltage. It is demonstrated that the CSI topology in conjunction with the developed switching pattern is capable of providing the required residential AC voltage from a low DC voltage of one PV panel at its rated power for both linear and nonlinear loads. In a micro-grid, the active and reactive power control and consequently voltage regulation is one of the main requirements. Therefore, the capability of the single-stage boost-inverter in controlling the active power and providing the reactive power is investigated. It is demonstrated that the injected active and reactive power can be independently controlled through two modulation indices introduced in the proposed switching algorithm. The system is capable of injecting a desirable level of reactive power, while the maximum power point tracking (MPPT) dictates the desirable active power. The developed switching pattern is experimentally verified through a laboratory scaled three-phase 200W boost-inverter for both grid-connected and stand-alone cases and the results are presented.

Oncolytic viruses (OVs) are effective anti-cancer agents, however their abilities to induce anti-tumor immunity are not yet optimal. Mutanome epitopes are a novel source of tumor antigen formed as a result of mutations within the tumor genome. Within this project we attempted to combine B16F10 mutanome vaccination with OV therapy. We confirmed previous findings that significant immune responses to these epitopes can be generated. Furthermore, we designed and cloned a multi-epitope mutanome construct into MG1 Maraba virus and E1-/E3- deleted type 5 Adenovirus to use for heterologous prime-boost vaccination. While we demonstrated that these viruses induced T-cell responses to one mutanome epitope, we failed to detect responses to the other epitopes. Furthermore there was no effect seen on overall survival. This approach warrants further investigation because coupling mutanome vaccination with OV therapy has the potential to exploit the therapeutic effects of the OV while inducing anti-tumor immunity to tumor-unique antigens.

Dans les nombreuses études actuelles sur le photovoltaïque, on assiste à de grands progrès tant dans le domaine des cellules à haut rendement énergétique, que sur les structures liées à l'exploitation. Afin de tirer parti de toute l'énergie produite, il a paru de tout premier ordre d'orienter les recherches sur les architectures parallèles en bus haute tension. Pour la génération de hautes tensions il est impératif d'utiliser des convertisseurs spécialement adaptés. En effet, si on utilise des convertisseurs classiques on se heurte à la problématique des pertes dans les composants de puissance, et notamment le transistor MOSFET de commutation utilisé pour le découpage. Une première étude a permis de vérifier que les contraintes de tension entraînent pour le transistor des pertes importantes aux tensions élevées. Cette première étude montre que seuls les transistors de faible tension inférieure à 100V ont des caractéristiques intéressantes pour notre application. Une recherche systématique a abouti à l'élaboration d'un convertisseur Boost à couplage magnétique. Grâce au recyclage des énergies parasites, les essais montrent que ce montage est bien adapté à notre application permettant d'obtenir des rendements de plus de 90%. Parmi les différentes stratégies d'extraction de puissance, le MPPT à incrément de conductance a été choisi pour ses qualités de précision et de facilité de mise en œuvre. Chaque panneau équipé d'un convertisseur envoie la puissance recueillie sur le bus haute tension, lui même relié à un onduleur de type SMA / In various studies on photovoltaic, major progresses have been observed, both concerning the cells and also in the field of their use. In order to take advantage of the energy it has been paramount to focus on parallel High Voltage bus. This High Voltage generation requires dedicated converters. In fact, using classical converters implicates important losses in the MOSFET used for switching. In a prior study we could ascertain important losses on transistors when submitted to high voltages as we assumed. It was shown then that only the transistors supporting a voltage less than 100V can be used for our application. A systematic investigation led to the Magnetically Coupled Boost converters. Thanks to the recycling of parasitic losses, our tests show an efficiency superior than 90%. Among the different power extraction strategies, the incremental conductance MPPT was used because of its top of the arts performances and convenience. Every DC/DC implemented panel converter supplies the HVDC bus which, itself, is connected to the SMA inverter

Battery-powered trends in consumer electronics, transportation, and renewable energy sectors increase demands on DC/DC converter technology. Higher switching frequency and efficiency reduces solution size and cost, while increasing power capabilities. Still, switching noise remains the primary drawback associated with any DC/DC converter. Reducing a converter’s input ripple helps prevent switching noise from spreading to other systems on a shared DC power bus. This thesis covers the analysis, simulation, and implementation of a recently-proposed boost converter topology, alongside an equivalent standard boost converter, operating in steady-state, continuous conduction mode. A Matlab-based simulation predicts each converter’s input ripple performance using a state-space model. The converters’ hardware implementation minimizes component and layout differences to create an equivalent comparison. The simulation and hardware measurements demonstrate a 40% input current ripple reduction using the modified topology. Replacing standard boost converters with the modified topology minimizes the switching noise conducted through a system’s DC power network.

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