This master´s thesis puts mind to choice and suggestion of suited type of DC/DC tension converter for power supply of power LED. It shows comparison of available types of accumulators in The Czech Republic and types of DC/DC converters used in construction of the sample. The choice of available source of energy is subordinated to final weight and size of a battery. There are also some explicit requirements for the smallest possible size and highest effictivity. So the choice is aimed only for converters with a simple coil and minimum numbers of switching elements to realize the converter, for example by SMT technology. One of many possibilities is LTC3453 circuit, which is described in this thesis, assembled and measured. On the basis of this circuit the next two samples are assembled. Here I try to suppress problems from previous circuit and expand it´s possibilities by adding the control of luminance via the microcontroller ATtiny. Then is introduced the basic description of flashlight Petzl MYO XP which is available in stores.

The aim of this diploma thesis is to study the resonant converters operation. This paper is concretely specialized to design and implementation the LLC resonant converter with output power about 350 watts. LLC resonant converter is prospective solution for similar applications. The general advantages are that the power MOSFETs are working on zero voltage switching condition, which reduce the switching loss and improve EMI performance. The detailed design for the LLC resonant tank characteristics presented in this paper, which fully guarantees the ZVS condition. This study is based on replacing the rectifier and load by an equivalent resistance applies the first harmonics approximation and the assumption that the current trough the diodes of the output rectifier has a sinusoidal waveform.

The first part of this work describes the design and implementation of switch-mode power supply for control circuits for 12/2x24V 4.5A fuel cells. The introduction picks the issue of power sources in electromobiles and final design and implementation of switching power suply. The next part deals with the issues of fast-charger and generators for power transistors. It describes the structure of DC converter and control and protectin circuits of quick-charger. In the end this work describes selected driver circuits and charge tests on fast-charger as evidenced by measurements.

This master thesis deals project and realization of universal transistor converter for power electronics course. For this converter was at the same time designed control circuit and drive circuit. Next part is about the design of compact converter for DC. This converter is controlled by a microprocessor Freescale.

L'amélioration de la compacité et du rendement des convertisseurs à découpage est une problématique centrale en électronique de puissance; elle l'est encore plus à bord des satellites où chaque gramme et chaque watt comptent. Chacun des nombreux émetteurs et récepteurs radiofréquence qui équipent les satellites de télécommunication a besoin d'être alimenté par diverses tensions, converties de façon isolée à partir du bus principal de distribution de puissance. En raison des lourdes contraintes thermiques, de fiabilité et de résistance aux radiations qui pèsent sur les composants électroniques dans les applications spatiales, les degrés de liberté pour améliorer les alimentations sont restreints, en tout cas avec les technologies actuelles de semiconducteurs qualifiés (couteuses et très en retrait des performances de l'état de l'art). La commercialisation assez récente de transistors de puissance en nitrure de gallium (GaN) à canal normalement bloqué, présentant des caractéristiques électriques supérieures à celles des meilleurs MOSFET de puissance en silicium, est prometteuse sur ce point. En effet leur robustesse intrinsèque aux radiations semble permettre leur emploi dans des convertisseurs spatiaux. Le but de ce travail est l'évaluation des apports possibles de cette technologie dans la réalisation d'alimentations DC/DC isolées pour des équipements typiques des charges utiles des satellites de télécommunication. Le fonctionnement à des fréquences de découpage plus élevées avec ces composants plus performants doit, au premier abord, réduire l'encombrement des convertisseurs à rendement égal (voire meilleur) tout en continuant à respecter le cahier des charges spécifique à chaque application. La pertinence de cette hypothèse et l'architecture de mise en œuvre la plus adéquate ont été explorées pour l'alimentation faible puissance d'un récepteur RF, avec réalisation et comparaison de plusieurs maquettes de démonstration. Afin d'aborder des convertisseurs de plus fortes puissances, une étude théorique et expérimentale des pertes par commutation dans les jambes de pont de transistors GaN a été menée. Un programme de calcul de performances a été développé en Python et mis en œuvre pour identifier l'optimum global du dimensionnement d'un convertisseur Dual Active Bridge destiné à l'alimentation d'un amplificateur RF de puissance (250 W DC). Une maquette prototype a été réalisée et a démontré l'intérêt de la topologie et des composants GaN dans cette application, tout en mettant en évidence la prédominance des pertes haute fréquence des composants magnétiques parmi les pertes totales du convertisseur. Ce dernier point s'avère finalement être la principale limitation de l'approche, précieuse pour l'ingénierie, de dimensionnement optimal par le calcul : les modèles actuellement existants d'estimation des pertes dans les éléments magnétiques se révèlent insatisfaisants pour prédire les performances de ce type de convertisseur. / Improving the compactness and efficiency of switching converters is a central issue in power electronics; even more so in satellites where every gram and every watt counts. Each of the many radio-frequency emitters and receivers onboard telecommunications satellites need to be powered by various voltages, converted in an isolated way from the main power distribution bus. Due to the strong thermal, reliability and radiation hardness constraints applying to electronic components in space applications, available degrees of freedom for improvement of power supplies are limited - at least with current qualified semiconductor technologies (which are both expensive and far behind state-of-the-art performance). The recent commercialization of gallium nitride (GaN) normally-off power transistors, having superior electrical characteristics compared to the best silicon power MOSFET, is promising on that regard. Indeed, their intrinsic radiation hardness seems to allow their use in space-grade converters. The aim of this work is the evaluation of how this technology can help improve the design of isolated DC/DC power supplies for typical hardware units of telecommunications satellite payloads. Operation at higher switching frequencies with these better performing components should, in principle, reduce converters' footprint while keeping the same (or better) efficiency level and still obeying each application's specific requirements. The accuracy of this hypothesis as well as the most adequate implementation architecture have been explored for the low power supply of a RF receiver, including realization and comparison of several demonstration boards. In order to approach higher power converters, a theoretical and experiment study of switching losses in GaN transistor bridge legs has been performed. A performance computation software has been developed in Python and used to identify the global optimum of the design of a Dual Active Bridge converter for a power RF amplifier (250 W DC). A prototype board has been built and demonstrated the interest of both the topology and GaN devices in this application, while clearly showing that high-frequency losses in magnetic components dominate total converter loss. This last issue happens to be the main limitation of the approach - precious to the engineer - of optimum design by computation: currently existing models for power loss estimation in magnetic elements are not satisfactory to predict performances of this type of converter.

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Over the past few years, the use of LEDs within the automotive and avionic industries has increased due to their high efficiency, durability and wide range of light brightness. As the use of LEDs within these industries grows, a need for reliable, high performance drivers becomes more relevant. Companies are implementing LEDs for applications involving adaptive lighting or simple dimming features. This thesis shows implementation of various non-isolated analog converters integrated with digital dimmers to achieve these adaptive lighting systems. Adaptive lighting systems involve reading an input from an external source (brake pedal or steering wheel) and changing the brightness and/or pattern of the brake/headlights to convey more information to the driver and their surroundings. The analog converters will implement Linear Technology’s LED driver IC’s, while the digital dimmers comprise of microcontrollers and discrete components. The design, simulation, and hardware verification will showcase the abilities of these analog converters. Results will demonstrate the proposed applications for both adaptive front and brake lighting.

DC-DC power converters play an important role in powering telecom and computing systems. With the speed improvement and cost reduction of digital control, digital controller is becoming a trend for DC-DC converters in addition to existed digital monitoring and management technology. In this thesis, digital control is investigated for DC-DC converters applications. To deeply understand the whole control systems, DC-DC converter models are investigated based on averaged state-space modeling. Considering half-bridge isolated DC-DC converter with a current doublers rectifier has advantages over other topologies especially in the application of low-voltage and high-current DC-DC converters, the thesis take it as an example for digital control modeling and implementation. In Chapter 2, unified steady-state DC models and small-signal models are developed for both symmetric and asymmetric controlled half-bridge DC-DC converters. Based on the models, digital controller design is implemented. In Chapter 3, digital modeling platforms are established based on Matlab, Digital PID design and corresponding simulation results are provided. Also some critical issues and practical requirements are discussed. In Chapter 4, a DSP-based digital controller is implemented with the TI's DSP chip TMS320F2812. Related implementation methods and technologies are discussed. Finally the experimental results of a DSP-based close-loop of HB converter are provided and analyzed in Chapter 5, and thesis conclusions are given in Chapter 6.

This work is focused on exploring advanced solutions for space power management and distribution (PMAD) systems. As spacecraft power requirements continue to increase, paralleled by the pressures for reducing cost and overall system weight, power electronics engineers will continue to face major redesigns of the space power systems in order to meet such challenges. Front-end PMAD systems, used to interface the solar sources and battery backup to the distribution bus, need to be designed with increased efficiency, reliability, and power density. A new family of integrated single-stage power converter structures is introduced here. This family allows the interface and control of multiple power sources and storage devices in order to optimize utilization of available resources. Employing single-stage power topologies, these converters control power flow efficiently and cost-effectively. This is achieved by modifying the operation and control strategies of isolated soft-switched half-bridge and full-bridge converters--two of the most popular two-port converter topologies. These topologies are reconfigured and utilized to realize three power processing paths. These paths simultaneously utilize the power devices, allowing increased functionality while promising reduced losses and enhanced power densities. Each of the proposed topologies is capable of performing simultaneous control of two of its three ports. Control objectives include battery or ultra-capacitor charge regulation, solar array maximum power point tracking (MPPT), and/or bus voltage regulation. Another advantage of the proposed power structure is that current engineering design concepts can be used to optimize the new topologies in a fashion similar to the mother topologies. This includes component selection and magnetic design procedures, as well as achieving soft-switching for increased efficiency at higher switching frequencies. Galvanic isolation of the load port through high-frequency transformers provides design flexibility for high step-up/step-down conversion ratios. It further allows the converters to be used as power electronics building blocks (PEBB) with outputs connected in different series/parallel combinations to meet different load requirements. Utilizing such converters promises significant savings in size, weight, and costs of the power management system as well as the devices it manages. Chapter 1 of this dissertation provides an introduction to the requirements, challenges, and trends of space PMAD. A review of existing multi-port converter technologies and digital control techniques is given in Chapter 2. Chapter 3 discusses different PMAD system architectures. It outlines the basic concepts used for PMAD integration and discusses the potential for improvement. Chapters 4 and 5 present and discuss the operation and characteristics of three different integrated multi-port converters. Chapter 6 presents improved methods for practical digital control of switching converters, which are especially useful in complex multi-objective controllers used for PMAD. This is followed by conclusions and suggested future work.

In this Dissertation, which concentrates on discrete modeling for control purposes of DC/DC converters and simulation through symbolic techniques. A Unified Discrete State-Space Model for power converters in CCM is presented. Two main approaches to arriving at the discrete model are used. The first approach involves an impulse function approximation of the duty cycle modulation of the converter switches, and this approach results in a small signal discrete model. The Second approach is direct and does not involve any approximation of the modulation, this approach yields both a large signal nonlinear discrete model and a linear small signal model. Harmonic analysis of the converter's states at steady-state is done for steady-state waveform acquisition, which increases the accuracy of the model especially for finding the control to inductor current frequency response. Also the harmonic Analysis technique is used to both obtain the response of the converter to a load transient and to finding the optimal duty cycle response that minimizes the disturbance. Finally the Discrete model is verified for the Half-Bridge DC/DC topology for its three main control schemes (Asymmetric, Symmetric, DCS). A GUI platform in MATLAB is presented as a wrapper that utilizes the models and analysis presented in this thesis. Symbolic simulation techniques are developed in general manner for linear piecewise circuits and then through State-Space formalism specialized for DC/DC converters. A general symbolic solver programmed in JAVA that implements said techniques is presented.