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Subwoofer for PA applications
Tylich, Ondřej ; Červinka, Dalibor (referee) ; Martiš, Jan (advisor)
The content of the bachelor´s thesis is theoretical knowledge in the field of loudspeaker baffles, their construction and design of the subwoofer according to the assignment. The work describes various types of used loudspeaker baffles. Their properties are defined for each of them. Some of the simulation programs are used for proper design. A suitable speaker is selected for the subwoofer application in PA technology. The parameters of the selected loudspeaker are verified by measurement. Based on these parameters, the design of the selected loudspeaker is calculated. Furthermore, the thesis addresses deals with the complete design process of the baffle for the selected speaker and its subsequent construction. After the construction, the port is tuned to the selected parameters. The resulting parameters of the designed subwoofer are verified by measuring the amplitude and frequency characteristics.
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Efficiency Improvement and Optimization of High Power Switching Converters
Martiš, Jan ; Dudrik,, Jaroslav (referee) ; Peroutka,, Zdeněk (referee) ; Vorel, Pavel (advisor)
This thesis focuses on optimization and increasing the efficiency of high-power DC/DC switching converters with transformer (switching power supplies). The work focuses mainly on using converters with flyback topology for high power, even though it is a common belief that this type of converter is not suitable for high power. This topology was selected because of potentially better achievable parameters, especially the efficiency, in comparison to a commonly used forward converter – in a flyback converter, losses are produced only in one magnetic component (transformer) in contrast to two components (transformer and inductor) in the forward converter. Compared to resonant and quasi-resonant converters, the flyback converter is easily controllable in the whole output voltage and current range. To make the flyback converter favorable for a high-power use, some innovative circuit modifications were made and modern semiconductor and passive components were used. Theoretical part of the work deals with efficiency optimization of the flyback converter, based on analytical solution. Operating parameters of the converter – switching frequency and parameters of the transformer (flux density and numbers of turns) are commonly only guessed or chosen from experience. The objective of this part is a mathematically exact determination of these parameters to achieve lowest total losses of the converter for given input parameters. In a certain case, it was possible to obtain the final solution analytically, in other cases the final solution step had to be done with a help of software. A prototype of a 12-kW switching power supply with a flyback converter was constructed to validate the proposed solutions and methods. The power supply fits into a space of only 33x33x16 cm. Modern semiconductors based on the silicon-carbide (SiC) technology (MOS-FET transistors and diodes) were used. After bringing the converter to a full-power operation, an efficiency of 96.8 % of the DC/DC converter was measured. High efficiency was obtained for a wide range of output parameters. A certain comparison with a forward converter with the same output parameters is done in the work. Not only from an efficiency point of view, the flyback converter seems very perspective.
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Plasma speaker - audio modulated electric arc
Klein, Ondřej ; Červinka, Dalibor (referee) ; Martiš, Jan (advisor)
The bachelor thesis deals with design and realization of electric arc modulated by audio signal. It is also known as plasma speaker. Absence of any mechanical components gives membranless speaker no frequency limitation. The design consist of single circuits as power sources for power and control section, control electronics, which modulates the signal, and power section, which reproduce signal in form of sound.
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Soldering gun with Li-Ion battery supply
Bartoš, Miroslav ; Vorel, Pavel (referee) ; Martiš, Jan (advisor)
This master‘s thesis deals with the design of battery powered soldering iron. The soldering iron will be placed in the plastic box from a conventional transformer soldering iron. First, we need to find the parameters of the original transformer soldering iron. Then design a synchronous step-down converter, driver of converter, BMS circuits, and component placement in a plastic box. The battery-powered soldering iron was successfully revived and tested, the final parameters of the converter are: voltage 0.4 V at 80 A current. The total power on the soldering wire is 32 W. Technically, this is a very interesting alternative to the classic version of the soldering iron, which can be used for assembly or repairs in poorly accessible locations.
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Apparatus for electromagnetic levitation
Kondys, David ; Vorel, Pavel (referee) ; Martiš, Jan (advisor)
This paper deals with magnetic levitation. It is divided into two main chapters. At the beginning of the first chapter, it discusses the types of magnetic levitation and describes their use in practice. It then focuses on the MAGLEV high-speed trains that use magnetic levitation. The second chapter is about the practical fabrication of equipment to demonstrate magnetic levitation. In the beginning, it discusses possible designs of magnetic levitation and evaluates this. Next, it simulates the chosen design and produces a graph from the simulations describing the force required to pick up a preselected object. It also discusses possible distance sensors that may be useful for this design. Finally, it describes the practical fabrication of the device design, i.e., the fabrication of the solenoid coil and the solenoid holder. Finally, it evaluates the measured values when the device is started.
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Charger for a battery supply of an oscilloscope
Novák, Miroslav ; Martiš, Jan (referee) ; Vorel, Pavel (advisor)
This bachelor thesis deals with the design and construction of a battery charger for an oscilloscope battery source. The output parameters of this charger are: output voltage 4.1 V and output current 15 A. The charger is designed as a flyback converter controlled by the integrated circuit UC3844. First, the possible topologies of the inverter are described. Then the selected flyback converter and the subsequent design of the power parts and the control circuit are described. Then the measurement where the transformer leakage was too large is described. Therefore, the following section describes the modification of the charger design, which uses a snubber network to eliminate the effect of leakage. This is followed by a description of the mechanical design of the charger. Finally, measurements of the charger are documented, testing problems are described, and the results obtained are evaluated.
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Electronic ballast for power LEDs
Vágner, Richard ; Martiš, Jan (referee) ; Červinka, Dalibor (advisor)
This diploma thesis deals with design of power LED driver. This driver contains electronic ballast circuits, converters, filters and control circuits. Overviews of circuits used in practice are listed along with analysis of power LED and considering options for selecting an appropriate design solution. Thesis describe principle of electroluminescense, creating of the device, its structure and problematics of current source supply. Including detailed overview of converters, ballasts and topologies used in lighting systems with the selection of a suitable solution for the final device with an output power of 50 W. The thesis contains cooling dimensioning for selected power LEDs, input circuit with EMI filter, bridge rectifier, boost converter and flyback converter with pulse transformer.
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