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Converter for supplying of the power LED diode
Puczok, Václav ; Huták, Petr (referee) ; Patočka, Miroslav (advisor)
The aim of this thesis is to design a grid-powered supply for supplying power LED used in illuminating application. The power supply consists of an input line filter which attenuates conducted high frequency signals (EMI filter), an active rectifier (PFC circuit) to improve the power factor and the main constant output current double-sided forward converter. It thoroughly focuses at design of the converter's power stage, mainly at pulse transformer, switching transistors, output rectifier and output filter. Main converter model was created in the Matlab-Simulink environment in order to simulate behaviour of the current loop. Final product of this work is a fully functional power supply and the main converter's model.
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Electronic power-supply for high-pressure lamps
Prachař, Petr ; Kubíček, Michal (referee) ; Šotner, Roman (advisor)
This paper describes the principle functions of high pressure sodium and metal halide lamps. Electronic control circuit involves specific feaures (dimming effect). The proposal is implemented with emphasis on high efficiency and high power factor. An important factor in the proposal is also possibility to connect a many types of high-pressure discharge lamps with different electrical properties. The output inverter operates in resonant mode at high frequency and it is controlled by a microprocessor. It is powered by a bridgeless buck power factor correction.
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Optimization of the active load of the source with dynamic output parameters
Halama, Petr ; Steinbauer, Miloslav (referee) ; Jirků, Tomáš (advisor)
This bachelor’s thesis deals with Power Factor Correction circuit, meant for the adjustment of the non-linear power source. Usually the PFC is designed for the power levels in the range of tens of Watts and more. New circuit will work at the power levels of maximally 1 W. Such control algorithm was designed, that the circuit represents the constant real load for an energy source. In the beginning of the work the Step-up converter topology was chosen as the best for next solution. More active PFC types were reviewed with the help of PSPICE simulator. In the next part of this project two of the analyzed circuits were implemented. Basic PFC for the demonstration of its principle and the half-bridge topology, which was selected on the basis of the analysis results.
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Power Factor Controllers for Switch-Mode Power Supllies
Gálus, Matej ; Steinbauer, Miloslav (referee) ; Murina, Milan (advisor)
The aim of this thesis is to design an active power factor correction (PFC) circuit for correcting a power factor of a switching power supplies. Various possible causes of bad AC mains power factor are discussed. Differences between linear and non-linear loads’ behaviour to AC mains are recognized and discussed. Various passive and active solutions for correcting current displacement and harmonic distortion are reviewed. Boost converter with quasi-resonant switching controlled by Texas Instruments’ UC3855 is chosen for highest total power factor for given power level against other topologies and its high efficiency and lower EMI against traditional boost converter. Various circuit parameters are simulated using PSpice. Complete circuit diagram for an 1kW output power level and worldwide mains voltage compatiblity is designed. After the device prototype was constructed, efficiency measurements were made and measured values are less than expected. This was apparently caused mainly due to absence of saturable reactor and implementation of resistive damping of the quasiresonant circuit’s parasitic resonance. Measured values of power factor are, however, very high and do meet the design expectations.
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Effect of Interlayer Composition on Bond Strength between FRC Framework and Composite Veneer
Ibarra, Jonatanh José ; Pavelka,, Vladimír (referee) ; Poláček, Petr (advisor)
Hlavním cílem této práce je studium aktuálního problému adheze mezi kompozitními materiály, a určení vlivu složení mezivrstvy v pevnosti adhezivního spoje mezi vláknové (FRC) a částicové (PFC) kompozity, používané ve stomatologii. FRC tyčinky byly vytvořené na bázi komerční dimetakrylatové pryskyřice a skleněných S vláken. PFC byl vytvořen ze směsi pryskyřic (bis-GMA a PEGDMA), plněných drceným barnatým sklem. Celkově bylo připraveno a vyzkoušeno 84 vzorků. Vzorky byly rozdělené do pěti hlavních skupin. První skupina byla vytvořena ze série vzorků bez mezivrstvy. Zbylé čtyři skupiny byly rozděleny dle složení mezivrstvy (tloušťky a druhu pryskyřic). Částicové kompozity vzorků se lišily obsahem plniva (0, 10, 40 hm %). FRC tyčinky byly stejné pro všechny vzorky. Univerzální testovací přístroj ZWICK Z010 byl použit k zjištění smykové pevnosti adhezivního spoje všech vzorků. Rastrovací elektronový mikroskop byl použít k pozorování místa porušení. Ze získaných výsledků vyplívá, že s přidáváním mezivrstvy mezi vláknovým a částicovým narůstá smyková pevnost spoje. Důležitost těchto výsledků je způsobená tím, že v posledních letech použití těchto materiálů ve stomatologii narůstá a adheze zůstává jeden z hlavních problémů při klinické praxi.
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