<p>In some turbochargers, boost pressure is reduced by opening the wastegate valve. In a modern turbo charged car, the most common way for opening the wastegate is with a pneumatic actuator and an air control solenoid, controlled by the ECU. In the control systems studied the ECU utilizes a static feedforward and a PID controller, for the purpose of making the boost pressure follow its reference value. With no systematic method for tuning the controller, this can be time consuming, and a set of well defined experiments to determine PID parameters are desired.When test time in a real engine is limited or expensive, it is advantageousto work in a simulation environment before doing live tests. A model for thewastegate actuator and air control solenoid is developed in the thesis. This is used to simulate controller performance before any tests in a real car is performed.In the thesis a tuning method for the PID controller based on step responsesis proposed. The tuning method evaluated is the IMC-choice of controller fora second order system, and it has a single design parameter not given by theexperiments. The controller is shown to give desired behavior when the staticfeedforward is correct or has small error.</p>

In some turbochargers, boost pressure is reduced by opening the wastegate valve. In a modern turbo charged car, the most common way for opening the wastegate is with a pneumatic actuator and an air control solenoid, controlled by the ECU. In the control systems studied the ECU utilizes a static feedforward and a PID controller, for the purpose of making the boost pressure follow its reference value. With no systematic method for tuning the controller, this can be time consuming, and a set of well defined experiments to determine PID parameters are desired.When test time in a real engine is limited or expensive, it is advantageousto work in a simulation environment before doing live tests. A model for thewastegate actuator and air control solenoid is developed in the thesis. This is used to simulate controller performance before any tests in a real car is performed.In the thesis a tuning method for the PID controller based on step responsesis proposed. The tuning method evaluated is the IMC-choice of controller fora second order system, and it has a single design parameter not given by theexperiments. The controller is shown to give desired behavior when the staticfeedforward is correct or has small error.

The traditional AC/DC rectifier usually has the defects of low power factor and serious harmonic distortion and it results in serious pollution to the power system. This thesis proposes active power factor correction technique using a new AC/DC Dual Boost Converter. For power factor correction, inductor current is operated in the continuous conduction mode. First, the converter is analyzed by state space averaging method. Furthermore, we design applicable compensator by frequency analysis to implement a good power factor system. A classical PFC circuit with PI control law has low power factor under light load. In order to overcome problem, the thesis proposes a Dual Boost Converter circuit with robust performance. Comparing with circuits using PFC IC ¡§UC3854¡¨, the proposed system obtains higher power factor under the condition of the same light load.

This thesis aims at investigating the technologies of the active power-factor correction (PFC) circuit. The system originally in the article is based on a boost converter circuit as the structure, the control method is to adopt the average current mode. We doesn¡¦t only narrate the circuit principle of the systematic circuit in the article but also use the OrCAD PSpice A/D software to simulation. Finally, we implemented make a prototype circuit and verified the proposed method. The experimental result shows that it can reach the goal for the power-factor correction.

This thesis mainly focuses on active power factor correction (PFC) circuit research. Based on DSP, a circuit with a digital controller is developed. Boost converter is used as the power stage. For power factor correction, the control law is realized with DSP and the control strategy of controller adopts the multi-loop method, i.e. voltage-loop and modified PI current-loop. Finally, compared with the circuit using the conventional PI control law, performances of the modified PI current-loop circuit are obviously optimized.

Η παρούσα διπλωματική εργασία πραγματεύεται τη μελέτη, την ανάλυση καθώς και την κατασκευή ενός μετατροπέα συνεχούς τάσεως σε συνεχή, ο οποίος μπορεί να χρησιμοποιηθεί σε ένα φωτοβολταϊκό σύστημα. Κατόπιν, η σύνδεση ενός αντιστροφέα στην έξοδο του μετατροπέα dc-dc επιτρέπει τη διασύνδεση του φωτοβολταϊκού συστήματος με το δίκτυο χαμηλής τάσης. Ο μετατροπέας dc-dc, που εξετάζεται στην παρούσα διπλωματική εργασία, είναι ένας νέος τύπος μετατροπέα που συνδυάζει ένα μετατροπέα Βoost με έναν Flyback με τη χρήση, όμως, ενός μόνο ημιαγωγικού στοιχείου. Με το μετατροπέα αυτό επιτυγχάνεται ανύψωση της τάσεως εισόδου, σε επίπεδα ικανά να οδηγηθεί η επόμενη βαθμίδα. Η εργασία αυτή εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών της Πολυτεχνικής Σχολής του Πανεπιστημίου Πατρών. Έχοντας ως πρώτο στόχο τη θεωρητική ανάλυση του προαναφερθέντος μετατροπέα και την εξαγωγή των χαρακτηριστικών καμπυλών εξόδου του, αυτό που αρχικά έγινε ήταν μια θεώρηση πως ο νέος αυτός μετατροπέας ισοδυναμεί με δύο άλλους, έναν Βoost και έναν Flyback συνδεδεμένους σε σειρά, και επομένως έχει τη δυνατότητα να περιγραφεί από τις εξισώσεις τους. Με βάση τη θεώρηση αυτή χρησιμοποιήθηκαν οι εξισώσεις του κάθε μετατροπέα για να προκύψουν οι χαρακτηριστικές καμπύλες εξόδου. Στη συνέχεια, προσομοιώθηκε με τη βοήθεια του προγράμματος PSpice τόσο ο σύνθετος μετατροπέας, όσο και ο συνδυασμός των δύο μετατροπέων και συγκρίθηκαν τα θεωρητικά αποτελέσματα με αυτά της προσομοίωσης και για τις δύο περιπτώσεις με στόχο την επιβεβαίωση της προτεινόμενης θεωρητικής ανάλυσης. Τέλος πραγματοποιήθηκε η κατασκευή του μετατροπέα αυτού με απώτερο σκοπό τη σύγκριση πειραματικών και θεωρητικών αποτελεσμάτων. / This study presents a detailed analysis of the overall behavior of a dc-dc single-switch boost-flyback step-up converter. The behavioral investigation is carried out supposing it consists of a boost in series with a flyback. The interesting thing of this converter is its modes of operation (continuous, discontinuous and mixed), which are depicted analytically. Simulation and experimental results by the construction of this converter validate the theoretical analysis.

Les Alimentations Sans Interruption (ASI) ont pour rôle de protéger les charges sensibles. Leur utilisation nécessite l’usage de convertisseur de puissance AC/DC triphasé abaisseur et/ou élévateur de tension. Les ASI utilisent généralement une chaîne de conversion DC/DC+DC/AC ayant un rendement aux alentours de et sont souvent employées de façon continue. L’objectif de cette thèse est donc d’étudier un convertisseur DC/AC triphasé réversible en puissance susceptible de fonctionner en abaisseur et en élévateur de tension pour atteindre un rendement souhaité de 98% avec un minimum de 97,5%. L’étude s’oriente vers des architectures de convertisseurs peu conventionnelles, l’utilisation de semi-conducteurs grand gap (SiC) et de composants passifs à faible pertes. Une méthode de comparaison rapide qui est à la fois analytique et numérique est présentée pour dimensionner ces architectures en se basant sur les caractéristiques fournies par les constructeurs. La solution ‘Gradateur Onduleur Différentiel’ a été jugée comme la plus adaptée à nos besoins. Les choix techniques pour ce convertisseur sont détaillés, puis une étude de faisabilité présentée. Le convertisseur retenu est non linéaire et sa commande utilise des principes de fonctionnement atypiques, différentes stratégies de régulation sont donc présentées. Des tests sont effectués pour valider la commande mise en place et réaliser les essais fonctionnels et mesures de rendement. Enfin les résultats sont comparés aux prévisions et la solution proposée est finalement globalement comparée à la chaîne de conversion AC/DC+DC/DC classique.

Στην παρούσα διπλωματική εργασία περιγράφεται η εφαρμογή μη γραμμικών μεθόδων ελέγχου στους Boost και Buck Boost DC-DC μετατροπείς που χρησιμοποιούν την τεχνική PWM. Συγκεκριμένα αναφερόμαστε στην μέθοδο ελέγχου βασισμένη σε παθητική σχεδίαση (PBC) καθώς και στην βασισμένη σε παθητική σχεδίαση μέθοδο ορισμού εσωτερικής ζεύξης και απόζευξης (IDA-PBC) και παρουσιάζουμε τα αποτελέσματα των εξομοιώσεων μέσω του προγράμματος Matlab-Simulink. Τέλος παρουσιάζεται ένας νέος μη γραμμικός-δυναμικός ελεγκτής, ικανός να διαμορφώσει την τάση εξόδου ανεξάρτητα από τον τύπο του φορτίου για τον DC-DC boost μετατροπέα. / The current diploma thesis discusses the application of nonlinear control methods for Boost and Buck Boost DC-DC converters using Pulse-Width-Modulation technique. Specifically we refer to the Passivity Based Control (PBC) as well as the Interconnection and Damping Assignment-Passivity Based Control (IDA-PBC) and Matlab-Simulink’s simulation results are presented. Finally, a new nonlinear dynamic control scheme suitable for DC-DC boost converter is introduced, capable of regulating the converter output at the desired level independently from the kind of the load.

Conselho Nacional de Desenvolvimento CientÃfico e TecnolÃgico / Este trabalho aborda os efeitos de afundamentos de tensÃo em Acionamentos de Velocidade VariÃvel â AVVs para mÃquinas de corrente alternada, conversores estÃticos de dois estÃgios (retificador-inversor) amplamente utilizados no controle de velocidade e traÃÃo. O estudo tem como objetivo analisar o comportamento dos AVVs diante de afundamentos de tensÃo simÃtricos e assimÃtricos e tÃcnicas de aumento de suportabilidade para estes equipamentos, destacando-se o uso de conversores boost. SÃo apresentados resultados de simulaÃÃes computacionais e de ensaios laboratoriais de um conversor boost desenvolvido para aumentar a tolerÃncia de AVV a afundamentos de tensÃo. Nos ensaios de laboratÃrio foram levantadas as curvas de tolerÃncia do AVV para afundamentos de tensÃo dos tipos A, B e E e comparadas aos limites estabelecidos pela curva SEMI F47 0706 do instituto EPRI. O AVV mostrou-se sensÃvel aos afundamentos tipo A e E com imunidade de tensÃo remanescente de atà 0,7pu na barra CC do AVV. Foram ainda feitos ensaios experimentais com o conversor boost conectado ao AVV sob condiÃÃes de afundamentos de tensÃo severos dos tipos A e E. A anÃlise do conjunto AVV-MIT sob os demais tipos de afundamentos de tensÃo (B, C, D, F e G) foi feita por simulaÃÃo computacional usando um modelo previamente validado pela comparaÃÃo com os resultados experimentais. Os afundamentos dos tipos A, E, F e G, que podem provocar o desligamento do AVV, foram tambÃm analisados por simulaÃÃes computacionais com a conexÃo do conversor boost ao barramento CC do AVV. Para a avaliaÃÃo do comportamento do AVV com e sem o conversor boost foram obtidas as curvas de tensÃo do barramento CC, tensÃo de saÃda do AVV, tensÃo de entrada do conversor boost, e de correntes de entrada do AVV, do conversor boost e de saÃda da fonte. Conforme os resultados de simulaÃÃes e experimentais o conversor boost pode mitigar afundamentos do tipo A para atà 0,5pu e todos os outros tipos de afundamentos atà nÃveis de interrupÃÃo, isto Ã, 0pu. Comparados os resultados com as simulaÃÃes de outras soluÃÃes abordadas no trabalho, o conversor boost se mostrou como a melhor alternativa do ponto de vista tÃcnico. / This work investigates the effects of voltage sags on Adjustable Speed Drives â ASDs of AC machines, static converters of two stages (rectifier-inverter) widely used on speed and torque control. The goal is to analyse the behavior of the ASDs under symmetrical and asymmetrical voltage sags and the approaches to improve the ASD low voltage ride-through capability with emphasis to the boost converter technique. Computational simulations and experimental results of a boost converter designed to operate when the ASD is under voltage sags are presented. The tolerance curves of the ASD were obtained in laboratory for voltage sags types A, B and E and compared to the SEMI F47 0706 curve of the EPRI institute. The ASD was shown sensitive for voltage sags types A and E with immunity for remaining voltages up to 0.7pu on the DC link. Experimental tests were performed to evaluate the response of the boost converter operation when the ASD is under severe voltage sag conditions of types A and E. The set ASD-induction motor was modelled for the simulation tests and the model validation was performed by comparison with experimental results. The analysis of the ASD and the three-phase induction motor under voltage sags B, C, D, F e G were carried out by computational simulations. The voltage sag types A, E, F and G which can turn off the ASD were also analyzed by computational simulation with the boost converter connected to ASD DC bus. The curves of DC link voltage, the ASD output voltage, the boost input voltage and the input currents of the ASD, the boost converter and the source were plotted for evaluation of the ASD behavior with and without the boost converter. The simulation and experimental results have shown that the boost converter can mitigate voltage sags type A up to 0.5pu and all other types of voltage sags up to 0pu. The boost converter has proved a suitable solution to improve the ASD voltage sag ride through capability.

CoordenaÃÃo de AperfeÃoamento de Pessoal de NÃvel Superior / This work presents procedures for modeling a Buck-Boost converter based on offline parametric identification techniques, with employment of black box and gray box models. For the identification of the control-to-output-voltage transfer function, the nonlinear Hammerstein model is employed, a particularly interesting structure to identify DC-DC converters for its ability to incorporate nonlinear static characteristic aside from the dynamic behavior of the plant. The identification of the mentioned transfer function is achieved from input and output data, obtained in simulations. In order to identify transfer function parameters, a restricted least squares algorithm is used. As for the identification of the control-to-inductor-current transfer function, a linear black box first order model is considered, with its parameters being determined from systemâs frequency response. In order to show the modelâs utility, a control system is designed based on the identified expressions. The control system employed is the digital version of type 3 compensator for the voltage loop and type 2 compensator for the current loop, both operating under or logics. The identification results of the system presented excellent agreement between the obtained parametric models and the converterâs behavior, showing the reliability of the identification techniques employed in this work. Furthermore, the control system designed from the identified transfer functions presented good performance, providing stability and quick disturbance rejection, bolstering the validity of parametric identification methods applied to the Buck-Boost converter. / Este trabalho apresenta procedimentos para a modelagem de um conversor Buck-Boost com base em tÃcnicas de identificaÃÃo paramÃtricas offline com emprego de modelos matemÃticos tipo caixa preta e caixa cinza. Para a identificaÃÃo da funÃÃo de transferÃncia que relaciona a tensÃo de saÃda e a razÃo cÃclica, à empregado o modelo nÃo linear de Hammerstein, estrutura particularmente interessante para aplicaÃÃo em identificaÃÃo de conversores CC-CC por incorporar a caracterÃstica estÃtica nÃo linear da planta de forma dissociada ao seu comportamento dinÃmico. A identificaÃÃo da funÃÃo de transferÃncia citada à feita a partir de dados de entrada e saÃda do sistema, medidos em simulaÃÃo. Para determinaÃÃo dos parÃmetros da funÃÃo de transferÃncia que relaciona a tensÃo de saÃda e a razÃo cÃclica, à utilizado um algoritmo de mÃnimos quadrados nÃo recursivo com restriÃÃes. Quanto à identificaÃÃo da funÃÃo de transferÃncia que relaciona a corrente no indutor e a razÃo cÃclica, à empregado um modelo caixa preta linear de primeira ordem, sendo os parÃmetros de tal modelo determinados a partir da resposta em frequÃncia do sistema. Visando mostrar a utilidade dos modelos paramÃtricos, à realizado um projeto de controle com base nas expressÃes identificadas. O sistema de controle adotado à a versÃo digital de um compensador tipo 3 para a malha de tensÃo e de um compensador tipo 2 para a malha de corrente, que operam de forma alternada segundo a lÃgica ou. Os resultados de identificaÃÃo do sistema apresentam uma excelente concordÃncia entre os modelos paramÃtricos obtidos e o comportamento do conversor, mostrando a confiabilidade das tÃcnicas de identificaÃÃo empregadas nesse trabalho. Adicionalmente, o sistema de controle projetado a partir das funÃÃes de transferÃncia estimadas apresentou bom desempenho, garantindo estabilidade e rÃpida rejeiÃÃo a distÃrbios, reforÃando a validade dos mÃtodos de identificaÃÃo paramÃtrica aplicados ao conversor Buck-Boost.