Switching device power losses place critical limits on the design and performance of high-frequency integrated DC-DC converters. Especially, the layout of metal interconnects in lateral power MOSFETs has a profound effect on their on-resistances and conduction power losses. This thesis presents an analytical interconnect modeling and layout optimization technique for large-area power MOSFETs. The layout optimization of 24V LDMOS transistors in the area of 1 mm2 has achieved an improvement of 55 % in its on-resistance. The simulation result has been verified by experimental measurements on a test chip fabricated in TSMC 0.25 µm HV CMOS technology. In addition, this thesis presents an optimized output stage design methodology for the implementation of a 4 MHz, 12V to 1V integrated DC-DC converter. A segmented output stage scheme is employed to increase the converter efficiency at light load conditions. The peak efficiency of 84% was achieved at load current of 2 A.

Switching device power losses place critical limits on the design and performance of high-frequency integrated DC-DC converters. Especially, the layout of metal interconnects in lateral power MOSFETs has a profound effect on their on-resistances and conduction power losses. This thesis presents an analytical interconnect modeling and layout optimization technique for large-area power MOSFETs. The layout optimization of 24V LDMOS transistors in the area of 1 mm2 has achieved an improvement of 55 % in its on-resistance. The simulation result has been verified by experimental measurements on a test chip fabricated in TSMC 0.25 µm HV CMOS technology. In addition, this thesis presents an optimized output stage design methodology for the implementation of a 4 MHz, 12V to 1V integrated DC-DC converter. A segmented output stage scheme is employed to increase the converter efficiency at light load conditions. The peak efficiency of 84% was achieved at load current of 2 A.

The paper discusses a design of a matrix LED display for car rear combination lamps and its power supply. It provides basic information about converters, light, and electronics requirements in the automotive industry. The design of individual circuits, printed circuit board, and firmware are analyzed. Predefined animations have safety, practical, and design functions. The innovative solution presents a new level of communication between the vehicle and its environment. The purpose is to increase safety and improve traffic flow.

This thesis proposes a control system to widen the bandwidth of piezoelectric transducers (PZTs) for vibration energy harvesting while extracting maximum power. A straightforward complex conjugate match achieves maximum power transfer only at a single frequency while requiring an impractically large inductance. The proposed system intends to address these problems. It incorporates a bi-directional DC/DC converter with feed-forward control to achieve a complex conjugate match over a wide range of frequencies.  Analysis of the proposed system and simulation results are presented to verify validity of the proposed method. / Master of Science

Fuel cells provide a clean and highly efficient energy source for power generation; however, in order to efficiently utilize the energy from fuel cells, a power conditioning system is required. Typical fuel cell systems for stand-alone and utility grid-tied stationary power applications are found mostly with low nominal output voltages around 24 V and 48 V, and power levels are found to be 3 to 10 kW [1][2]. A power conditioning system for such applications generally consists of a dc-dc converter and a dc-ac inverter, and the dc-dc converter for low-voltage, high-power fuel cells must deal with a high voltage step-up conversion ratio and high input currents. Although many dc-dc converters have been proposed, most deal with high input voltage systems that focus on step-down applications, and such dc-dc converters are not suitable for low-voltage, high-power fuel cell applications. Multiphase isolated dc-dc converters offer several advantages that are very desirable in low-voltage, high-power fuel cell applications. First, a multiphase is constructed with paralleled phases, which increase power rating and current handling capability for high input current. Second, an interleaving control scheme produces a high operating frequency with a low switching frequency, and the high operating frequency reduces size of passive components. Thirdly, use of a transformer provides electrical isolation and a high conversion ratio. Lastly, several multiphase converters are capable of soft-switching operation, which increases converter efficiency. This thesis examines two highly efficient, soft-switching dc-dc converters that are targeted for fuel cell applications. The thesis also describes the converters' basic operating principles and analyzes performance for low-voltage, high-power fuel cell applications. 5-kW prototypes for each converter are built and tested with a fuel cell simulator. Experimental switching waveforms and efficiency profiles are shown to support the described basic principles and the analysis. Major features and differences between these two converters are also discussed. / Master of Science

Η παρούσα διπλωματική εργασία πραγματεύεται το σχεδιασμό και την κατασκευή διάταξης φόρτισης του κινητήρα ενός ηλεκτροκίνητου οχήματος. Η εργασία αυτή εκπονήθηκε στο Εργαστήριο Ηλεκτρομηχανικής Μετατροπής Ενέργειας του Τμήματος Ηλεκτρολόγων Μηχανικών και Τεχνολογίας Υπολογιστών της Πολυτεχνικής Σχολής του Πανεπιστημίου Πατρών. Κύριος σκοπός της διπλωματικής εργασίας είναι η κατασκευή ενός αμφίδρομου ηλεκτρονικού μετατροπέα ισχύος, που θα ελέγχει μια μηχανή συνεχούς ρεύματος ξένης διέγερσης, η οποία συνδέεται μέσω ενός συστήματος μετάδοσης με τον κινητήρα ενός ηλεκτροκίνητου οχήματος. Απώτερος στόχος είναι η εξομοίωση όλων των πιθανών φορτίων που ασκούνται σε έναν κινητήρα κατά την κίνηση του οχήματος. Αρχικά αναλύεται το φορτίου του κινητήρα κατά την κίνηση του οχήματος και αναζητούνται τρόποι για την εξομοίωση και τη σύνδεση των εξωτερικών δυνάμεων που ασκούνται στο όχημα με τη ροπή της μηχανής. Στη συνέχεια αναλύθηκε ο αμφίδρομος ηλεκτρονικός μετατροπέας που χρησιμοποιήθηκε για τον έλεγχο της μηχανής συνεχούς ρεύματος και αναζητήθηκαν οι κατάλληλες μέθοδοι για τον έλεγχο του συγκεκριμένου μετατροπέα. Το επόμενο βήμα ήταν η προσομοίωση του συνολικού συστήματος φόρτισης προκειμένου να εξακρθωθεί η ορθή λειτουργία του πριν την κατασκευή, με χρήση του λογισμικού MATLAB/SIMULINK. Τέλος, μελετάται και κατασκευάζεται στο εργαστήριο η πειραματική διάταξη, με τη χρήση της οποίας διεξάγονται οι μετρήσεις για την επιβεβαίωση και την αξιολόγηση της θεωρητικής μελέτης. / This thesis discusses the design and manufacture of a charging device intended for an electric vehicle motor. The work was conducted in the Laboratory of Electromechanical Energy Conversion, Department of Electrical and Computer Engineering, School of Engineering, University of Patras. The main purpose of this thesis is to manufacture a bidirectional electronic power converter able to control a DC motor which is connected with the engine of an electric vehicle via a transmission system. The ultimate goal is to simulate all possible loads exerted on a motor during the vehicle movement. Initially we analyze the load on the engine during vehicle movement and seek ways to simulate and combine the external forces acting on the vehicle with the engine torque. In the sequel the bidirectional electronic power converter used to control the DC motor is analyzed and appropriate control methods are investigated. The next step is to simulate and validate the overall system functionality using MATLAB / SIMULINK, before actually proceeding with the manufacture. Finally, an experimental setup is prepared in our lab, the results of which are utilized to confirm and evaluate the aforementioned theoretical study.

Increasing the power density of power electronic converters while reducing or maintaining the same cost, offers a higher potential to meet the current trend inrelation to various power electronic applications. High power density converters can be achieved by increasing the switching frequency, due to which the bulkiest parts, such as transformer, inductors and the capacitor's size in the convertercircuit can be drastically reduced. In this regard, highly integrated planar magnetics are considered as an effective approach compared to the conventional wire wound transformers in modern switch mode power supplies (SMPS). However, as the operating frequency of the transformers increase from several hundred kHz to MHz, numerous problems arise such as skin and proximity effects due to the induced eddy currents in the windings, leakage inductance and unbalanced magnetic flux distribution. In addition to this, the core losses whichare functional dependent on frequency gets elevated as the operating frequency increases. Therefore, this thesis provides an insight towards the problems related to the high frequency magnetics and proposes a solution with regards to different aspects in relation to designing high power density, energy efficient transformers.The first part of the thesis concentrates on the investigation of high power density and highly energy efficient coreless printed circuit board (PCB) step-down transformers useful for stringent height DC-DC converter applications, where the core losses are being completely eliminated. These transformers also maintain the advantages offered by existing core based transformers such as, high coupling coefficient, sufficient input impedance, high energy efficiency and wide frequencyband width with the assistance of a resonant technique. In this regard, several coreless PCB step down transformers of different turn’s ratio for power transfer applications have been designed and evaluated. The designed multilayered coreless PCB transformers for telecom and PoE applications of 8,15 and 30W show that the volume reduction of approximately 40 - 90% is possible when compared to its existing core based counterparts while maintaining the energy efficiency of the transformers in the range of 90 - 97%. The estimation of EMI emissions from the designed transformers for the given power transfer application proves that the amount of radiated EMI from a multilayered transformer is lessthan that of the two layered transformer because of the decreased radius for thesame amount of inductance.The design guidelines for the multilayered coreless PCB step-down transformer for the given power transfer application has been proposed. The designed transformer of 10mm radius has been characterized up to the power level of 50Wand possesses a record power density of 107W/cm3 with a peak energy efficiency of 96%. In addition to this, the design guidelines of the signal transformer fordriving the high side MOSFET in double ended converter topologies have been proposed. The measured power consumption of the high side gate drive circuitvitogether with the designed signal transformer is 0.37W. Both these signal andpower transformers have been successfully implemented in a resonant converter topology in the switching frequency range of 2.4 – 2.75MHz for the maximum load power of 34.5W resulting in the peak energy efficiency of converter as 86.5%.This thesis also investigates the indirect effect of the dielectric laminate on the magnetic field intensity and current density distribution in the planar power transformers with the assistance of finite element analysis (FEA). The significanceof the high frequency dielectric laminate compared to FR-4 laminate in terms of energy efficiency of planar power transformers in MHz frequency region is also explored.The investigations were also conducted on different winding strategies such as conventional solid winding and the parallel winding strategies, which play an important role in the design and development of a high frequency transformer and suggested a better choice in the case of transformers operating in the MHz frequency region.In the second part of the thesis, a novel planar power transformer with hybrid core structure has been designed and evaluated in the MHz frequency region. The design guidelines of the energy efficient high frequency planar power transformerfor the given power transfer application have been proposed. The designed corebased planar transformer has been characterized up to the power level of 50W and possess a power density of 47W/cm3 with maximum energy efficiency of 97%. This transformer has been evaluated successfully in the resonant converter topology within the switching frequency range of 3 – 4.5MHz. The peak energy efficiency ofthe converter is reported to be 92% and the converter has been tested for the maximum power level of 45W, which is suitable for consumer applications such as laptop adapters. In addition to this, a record power density transformer has been designed with a custom made pot core and has been characterized in thefrequency range of 1 - 10MHz. The power density of this custom core transformer operating at 6.78MHz frequency is 67W/cm3 and with the peak energy efficiency of 98%.In conclusion, the research in this dissertation proposed a solution for obtaining high power density converters by designing the highly integrated, high frequency(1 - 10MHz) coreless and core based planar magnetics with energy efficiencies inthe range of 92 - 97%. This solution together with the latest semiconductor GaN/SiC switching devices provides an excellent choice to meet the requirements of the next generation ultra flat low profile switch mode power supplies (SMPS).

L'avion plus électrique est un concept qui a le vent en poupe chez les principaux constructeurs du domaine de l'aéronautique. Dans ce domaine, comme dans d'autres, les besoins en énergie électrique sont croissants et nécessitent de mettre en place des systèmes de conversion d'énergie fiables, performants et modulaires. Ces systèmes de conversion sont souvent couplés avec des systèmes de stockage d'énergie (type batterie) permettant dans certaines situations de rendre l'avion énergétiquement autonome grâce à une source de puissance indépendante des principaux organes de production d'énergie. Cette interconnexion batterie - réseau de bord présente un rapport de tension élevé ce qui, ajouté aux fortes valeurs de courant de la basse tension, en fait un objet particulièrement complexe à réaliser.L'objectif de cette thèse est de concevoir de manière optimale un convertisseur de puissance isolé permettant l'interconnexion d'un bus basse tension 28 V (typiquement des batteries) à un bus haute tension 540 V (réseau de bord de l'avion) avec une puissance échangeable d'environ 12 kW. Elle se déroule dans le cadre d'un projet ANR (quatre partenaires universitaires, associés à l'entreprise AIRBUS) dont l'une des tâches est le développement d'outils de conception pour l'électronique de puissance. Le travail correspondant comprend une contribution à cette tâche sous forme de la construction de modèles des principaux composants intervenant dans un convertisseur, modèles destinés à être intégrés dans les routines d'optimisation. Pour cette raison, ils seront analytiques (physique, empiriques, mélange des deux).Ces modèles seront ensuite insérés dans un outil global développé dans une autre thèse du projet, à l'aide duquel différentes architectures de convertisseurs seront comparées afin d'en déduire la meilleure solution pour le cahier des charges énoncé précédemment. Un prototype du convertisseur retenu sera finalement réalisé en utilisant des technologies avancées, pour conduire une validation expérimentale. / The electric aircraft tends to become widespread at all the main manufacturers of the domain of the aeronautics. Needs do not stop growing and require setting up reliable, efficiency and modular systems of conversion of energy. These systems of conversion are often coupled with systems of storage of energy (battery) allowing in certain situations to make the punctually autonomous aircraft energetically thanks to a source of power independent from main organs of power production. This interconnection battery - network of edge presents a very high report of rise of tension what, added to the high current value of the battery bus, in fact a particularly complex object to be realized.The objective of this thesis is to design in an optimal way a converter of power isolated allowing the interconnection of a low-voltage bus 28V (typically batteries) in a high-voltage bus 540V (network of edge of the aircraft) with an exchangeable power about 12 kW. It takes place within the framework of an ANR project (four university partners + AIRBUS) the development of tools of conception of which one of the tasks is for the ENP. The corresponding work includes a contribution to this task in the form of the construction of models of the main components occurring in a converter, model intended to be integrated into the routines of optimization. For that reason, they will be analytical (physical, empirical or mix both).These models will then be inserted into a global tool developed in another thesis of the project, by means of which various architectures of converters will be compared to deduct the best solution from it for the previous specifications. A prototype of the reserved converter will be finally realized by using advanced technologies, to lead an experimental validation.

<p>A Sliding Mode Control System for a Bidirectional DCDC Converter was designed and a low voltage prototype was constructed. The control system based its decisions solely on the latest available measurements, which improves performance when changing operative quadrant, since no memory needs reinitializing (such as for PI and state prediction methods). A boost control philosophy was presented, based on a current source approximation. The control was found to be stable without steady-state errors when the variance of the input/output dynamics was high.</p><p>The target application for the DCDC Converter is an EV (Electric Vehicle) with a flywheel driveline, which puts additional requirements of the converter. Among these are current and voltage control, bidirectionality, and a broad input voltage range.</p><p>Simulations were performed in Simulink prior to physical implementation, proving functionality of the proposed control system. The physical implementation of the control was done on a digital signal processor with code compiled from C. A median filter was designed to increase measurement efficiency for the current sensors which had shot-like noise distortions.</p>

A Sliding Mode Control System for a Bidirectional DCDC Converter was designed and a low voltage prototype was constructed. The control system based its decisions solely on the latest available measurements, which improves performance when changing operative quadrant, since no memory needs reinitializing (such as for PI and state prediction methods). A boost control philosophy was presented, based on a current source approximation. The control was found to be stable without steady-state errors when the variance of the input/output dynamics was high. The target application for the DCDC Converter is an EV (Electric Vehicle) with a flywheel driveline, which puts additional requirements of the converter. Among these are current and voltage control, bidirectionality, and a broad input voltage range. Simulations were performed in Simulink prior to physical implementation, proving functionality of the proposed control system. The physical implementation of the control was done on a digital signal processor with code compiled from C. A median filter was designed to increase measurement efficiency for the current sensors which had shot-like noise distortions.