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DISCONNECTOR PARALLEL CURRENT PATHS OPTIMIZATION
Görig, Tomáš ; Tůma, Jan (referee) ; Dohnal, Petr (advisor)
The objective of this master´s thesis is diagnostic the actual disconnector current path that is unevenly stressed by nominal current. The most stressed parts are excessively heated. In next part are projected a few options to optimize the current path. The options are verified by simulation. The best option is recommended to the submitter.
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Influence of skin effect, proximity effect and air gap on winding losses of HF inductors and transformers
Pitner, Tomáš ; Cipín, Radoslav (referee) ; Martiš, Jan (advisor)
The bachelor's thesis deals with power losses in the windings of high-frequency inductors and transformers. A detailed mathematical and qualitative analysis of the skin effect, proximity effect and leakage flux of air gap is performed, supplemented with the results of computer simulations using the finite element method. The thesis introduces analytical and numerical methods for calculating power losses in the windings of inductors and transformers and describes suitable measurement methods, which are further used in the thesis. For selected geometries of inductors and transformers, AC resistances of their windings are calculated using FEM and the results are compared with measurements on constructed prototypes. The winding geometries are also compared between each other.
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Skin effect in high-speed electrical machines.
Klíma, Petr ; Bárta, Jan (referee) ; Mach, Martin (advisor)
This master thesis deals with the suppression of the skin and proximity effects in high-speed machines. The first part summarizes the general knowledge of high-speed machines. The second part is devoted to the principle and possible suppression of consequences caused by skin and proximity effects. The third part shows the simulation results of models of a synchronous machine with permanent magnets. The results of these simulations reveal the consequences of skin and proximity effects. In addition, design measures are proposed to limit these and other undesirable phenomena to achieve the highest possible efficiency.
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FEM analysis of overcurrent trip unit
Makki, Zbyněk ; Augusta, Zbyněk (referee) ; Valenta, Jiří (advisor)
The aim of the project was to prepare the given model of the current path in the environment of the SolidWorks programme, in order to simulate the flow path in the environment of the Ansys programme, where there was calculated the distribution of current density,voltage drops and heat loss on the the specified current track according to specified conditions. The obtained results are analyzed at the conclusion of this work.
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Combined Electron Beam Lithography
Krátký, Stanislav ; Mikulík, Petr (referee) ; Škereň,, Marek (referee) ; Kolařík, Vladimír (advisor)
This thesis deals with grayscale e-beam lithography and diffractive optical elements fabrication. Three topics are addressed. The first topic is combined grayscale e-beam lithography. The goal of this task is combining exposures performed by two systems with various beam energies. This combined technique leads to a better usage of both systems because various structures can be more easily prepared by one electron beam energy than by the other. The next topic is the optimization of shape borders of exposing structures that are defined by image input. The influence of such optimization on exposure data preparation is evaluated, as well as the exposure time and the change of optical properties of testing structures. The possibility of deep multilevel diffractive optical element fabrication in plexiglass blocks is researched as the third topic. Plexiglass can replace the system of a resist and a substrate. A new approach to writing down the structures by electron beam is presented, minimizing thermal stress on the plexiglass block during the exposure. The writing method also improves the homogeneity of exposed motifs. A method for computing the exposure dose for specific multilevel structures was designed. This method is based on the existing model of proximity effect computation and it minimizes the computing time necessary to obtain the exposure doses.
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The construction for the innovative Jecklin Disk microphone technique
Strážnický, Martin ; Musil, Jaroslav (referee) ; Jirásek, Ondřej (advisor)
The thesis deals with the design and subsequent measurement of the parameters of the Jecklin disc pair microphone array. The theoretical part deals with human hearing, microphone characteristics and types of stereo microphone technology. The practical part focuses on the measurement of the directivity and width of the stereo image when changing the configuration of the array. The measured results are then verified in practice by recording acoustic musical instruments.
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Influence of skin effect, proximity effect and air gap on winding losses of HF inductors and transformers
Pitner, Tomáš ; Cipín, Radoslav (referee) ; Martiš, Jan (advisor)
The bachelor's thesis deals with power losses in the windings of high-frequency inductors and transformers. A detailed mathematical and qualitative analysis of the skin effect, proximity effect and leakage flux of air gap is performed, supplemented with the results of computer simulations using the finite element method. The thesis introduces analytical and numerical methods for calculating power losses in the windings of inductors and transformers and describes suitable measurement methods, which are further used in the thesis. For selected geometries of inductors and transformers, AC resistances of their windings are calculated using FEM and the results are compared with measurements on constructed prototypes. The winding geometries are also compared between each other.
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