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Switching driver for high power LEDs with higher efficiency
Doležal, Miroslav ; Háze, Jiří (referee) ; Šteffan, Pavel (advisor)
Problems in swithing converter and power losses in this circuit describe these master’s theses. Power losses have the primar influence on the total effectivity circuit. The first chapter deal swith principle of basic parts switching converter (buck, boost, buck-boost). The power losses on main elements used in switching circuit (diode, transistor) are explained in the next part this thesis. Theory of synchronous rectifiction for reduction of losses. A choice of two integrated circuit useful for future design of LED driver working in buck-boost mode is on the end of the theoretical part. The practical part is fosud on the design of circuits (with integrated circuits chose in the theoretical part) including schematic diagram, calculation of parts and PCB layout. The build samples are evaluated by set of measurements in the field of effeciency, temperatures of components, stability output LED current, EMC and soon. Finally the particular parameters of both tested circuits are compared
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Drivers for power switching transistors GaN MOSFET
Fiala, Zbyněk ; Pazdera, Ivo (referee) ; Vorel, Pavel (advisor)
The thesis describes the procedure during the proposal of the driver circuits for the GaN MOSFET transistors, which are known for their fast switching especially. In the first instance of this thesis the issue of GaN MOSFET transistors is described and also the thesis describes the different types of MOSFET transistors in the way of their electrical and mechanical attributes. The specific type driver circuit is stated in the thesis, which was selected in the semestral thesis. For this circuit the boost converter with an output power 600W and high switching frequency 800kHz was proposed as an attempt measurement circuit. This boost converter was measured after its construction was done. The waveforms captured by the oscilloscope are commented also. In the conclusion the assessment is done about this new technology of power switching transistors.
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HAM Station Log Book for Linux
Kaluža, Jan ; Růžička, Richard (referee) ; Šimek, Václav (advisor)
The goal of this bachelor's thesis is to design and implement an amateur radio logbook software for a GNU/Linux operating system. After the short introduction there are described existent logbook applications together with analysis of their advantages and disadvantages. Based on this analysis the logbook application is designed and implemented. Finally, there is a summary and discussion of possibilities for further improvements.
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Synchronization and Backup od Data under OS Linux
Marťák, Adam ; Rychlý, Marek (referee) ; Očenášek, Pavel (advisor)
This bachelor's thesis deals with synchronisation and backup of data under Linux OS. The aim of this paper is to design and implement a custom tool for data synchronisation and backup for Linux OS. The solution was inspired by the program Git. The architecture peer-to-peer was used to implement the project. The tool uses a database to store metadata and data itself. Based on testing, it was found that the tool has a certain overhead during the data synchronisation and the process of backing up. These results are discussed and other proposals are submited in the conclusion.
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Ray-tracing Using IPP Library
Kukla, Michal ; Havel, Jiří (referee) ; Hradiš, Michal (advisor)
Master thesis is dealing with design and implementation of ray-tracing and path-tracing using IPP library. Theoretical part discusses current trends in acceleration of selected algorithms and also possibilities of parallelization. Design of ray-tracing and path-tracing algorithm and form of parallelization are described in proposal. This part also discusses implementation of adaptive sampling and importance sampling with Monte Carlo method to accelerate path-tracing algorithm. Next part is dealing with particular steps in implementation of selected rendering methods regarding IPP library. Implementation of network interface using Boost library is also discussed. At the end, implemented methods are subjected to performance and quality test. Final product of this thesis is server aplication capable of handling multiple connections which provides visualisation and client application which implements ray-tracing and path-tracing.
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Methods for Analysis of Switched Circuits
Kovář, Jan ; Ondráček, Oldřich (referee) ; Kalous, Jaroslav (referee) ; Kolka, Zdeněk (advisor)
The dissertation deals with simulations of the DC-DC converters in their basic configurations (Buck, Boost, Buck-boost, Cuk, SEPIC). In the first part of the thesis derivation of transfer functions Line-to-Output (LTO) and Control-To-Output (CTO) can be found. These symbolic responses are derived for three types of basic converters (Buck, Boost, Buck-boost) using well-known average model [1]. Derived expressions are very complicated. For reduction of these expressions symbolic approximation method was used, however the generality is lost. The average model was used to for decreasing the computational effort of analysis of DC-DC converters in the time domain. For these simulations VHDL-AMS language was used. The main topic of the thesis is harmonic balance method, which was adapted to DC-DC converters. Because conditions and assumptions for LTO and CTO functions are very different, harmonic balance method was derived into two variants. For obtaining of LTO response, duty cycle of switching signal can be considered as constant in time. Spectrum of this signal is simple as follows from well-known sinc function. For obtaining of CTO response PWM modulation must be used. Compared to sinc function spectrum of PWM modulation is richer (contains more combination frequencies). Many types of PWM modulation is described in [31]. For simulation PWM modulation with uniform sampling in two variants (single and double edge) was used. Non-ideal switching of PWM switch was modeled by PWM pulse with defined slew rate. Last section deals with comparison of all derived functions (LTO, CTO, modulation type, defined slew rate) with well-known averaged model.
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Analysis of switched-mode LED drivers
Stehlík, Ota ; Vyskočil, Pavel (referee) ; Kubíček, Michal (advisor)
The aim of this thesis is to design, produce and verify the operation of two different LED drivers for automotive industry, which controls the ultra-bright white LEDs. At the beginning of a brief introduction explaining the principle of operation of LEDs. Furthermore theory describes the functions of all three basic drivers involved as buck, boost and buck-boost. Based on the requirements are selected ICs suitable for this implementation, theoretically described their block diagrams including the individual diagrams and eventually these samples are made, revived and measured their parameters.
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Driver for LED automotive lights
Christen, Jiří ; Vochyán, Josef (referee) ; Dřínovský, Jiří (advisor)
This master's thesis deals with a design and realization of a LED driver that is based on integrated circuits NCV78703 and NCV78723 from ON Semiconductor. The aim of the project is to create a demonstration application with these integrated circuits for the use of company. The circuits can be especially used for driving LED automotive lights. The driver is controlled with a microcontroller also providing a communication with a software running on a PC via USB interface. This software enables to simply modify parameters of the driver in order to adjust an intensity of LEDs.
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Passive PFC filters for SMPS
Matejov, Michal ; Červinka, Dalibor (referee) ; Drápela, Jiří (advisor)
This work deals with theory of switched power sources. There is description of the ways for connection and their practice purposes. In the next parts there are defined requirements on input supply circuit for these sources, especially for the form of output current. There are mentioned the basic connecting methods of PFC circuits and these methods modify the output current to meet the requirements of specification ČSN EN 61000- 3- 2. In the next parts there are shown simulations of PFC circuits made by Pspice application. Further is the basic description of sources construction for the sources which were used for testing and measuring. The final part deals with evaluation of the measuring on the chosen computer’s source. It compares between the manufacturer’s solutions and PFC circuit made by ourselves.
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The usage of brachytherapy in treatment of breast cancer
BURIANOVÁ, Klára
This project is dealing with comparsion of results treatment with both methods (HDR therapy and electron therapy) at patients who was threated in oncology department in České Budějovice in years 2001 - 2003. The results of treatment both methods (numer of relapses, cosmetic effekt) have to equivalent. It was realized on the base of searching in medical documentation and post processing.
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