|
|
Study of the Ta2O5 insulating layer degradation
Velísek, Martin ; Majzner, Jiří (referee) ; Sedláková, Vlasta (advisor)
The aim of the thesis is to examine the dielectric function Ta2O5 insulating layers in tantalum capacitors. The capacitor plugged in the regular mode represents a MIS structure of reverse direction. Three different factors can be determined for the residual current of the component according to its charge transmission mode: the ohmic, Pool–Frenkel, tunnel and Schottky. An apparatus was constructed by the author of the thesis to measure the temporary connection between residual current and rise of temperature of the tantalum capacitors. Annealing of three different sets of tantalum capacitors made by different producers was performed at the temperature of 400 K and nominal voltage of 35 V during the period of 20 days.The experiment has proved the residual current in the electric field changes with rising temperature in time as a result of the ion movement. The singular factors of the residual current are influenced during the process. By the “ion movement” is meant the ion drift influenced by the attached electric field and diffusion caused by the concentration gradient. First, the samples were being annealed for c. 2 x 106 s, and then the residual current was being regenerated under the voltage of 5 V for 106 s. The residual current values increased considerably after annealing, and decreased again to more or less the original level after the regeneration, some of the samples reaching even values bellow the original level. The VA characteristics of the samples measured before and after the process of controlled obsolescence, and after the regeneration prove not only a change in parameters of the different current factors, but also a change of the current transmission mechanism employed in the process.
|
|
|
Study of CdTe sensor properties
Vašíček, Martin ; Holcman, Vladimír (referee) ; Grmela, Lubomír (advisor)
This Bachelor Thesis is focused on studies of CdTe detector characteristics. It is to describe the analysis of transport and noise characteristics of CdTe samples at different temperatures. Evaluation of our results proves that CdTe junction behaves like an antiseries connection of a pair of diodes. The courses of VA characteristics are noted for linear or slightly exponential growth. When temperature is growing , conductivity of the samples is growing too. Our measurements demonstrated difference in conductivity of samples tested at the same temperature. It is also obvious that within very low range of frequencies the factor of noise 1/f is dominating. From 10Hz frequency the effect of thermal noise prevails.
|
|
| |
|
|
Design of VA-characteristic meter
Štěpnička, Martin ; Szabó, Zoltán (referee) ; Steinbauer, Miloslav (advisor)
The thesis describes the design of a measuring device volt-ampere characteristics of PN junction suitable for measuring characteristics of stabilizing diodes. Describes the basic principle of PN junction and related events. Part of the text discusses how to minimize the adverse parasitic effects. Furthermore, the proposal deals with an AC adapter suitable for this device. With that analyzes marginally rectifiers, stabilizers and filters. The following is a description of the device for measurement, principle of communication with the computer and the method of data processing. The annex contains schematic design, printed circuit boards and part list.
|
|
|
V-I characteristic of solar cells
Kaderka, Tomasz ; Křivík, Petr (referee) ; Vaněk, Jiří (advisor)
The theoretical part is to outline the possibilities of solar energy conversion, learn about the issues solar cells and describe the history of photovoltaics and photovoltaic energy conversion. Then describe principle of the measurement VA characteristics of photovoltaic cells. This issue is not as easy as it seems at first sight, because the solar cell isn’t a linear component, which is very easy to measure. Analysis of VA characteristic of photovoltaic cells affects parameters such as: light intensity, temperature, serial and parallel resistance, the slope of the light source, and more. The practical part deals with creating a workplace for automatic measurement of VA characteristics of photovoltaic cells in the LabVIEW. Challenge is to create a functional program, which automatically measures the VA characteristics not only in the lighted cells, but also in the shaded cell (diode mode). The program calculates the power and important parameters, such as short-circuit current, open circuit voltage, maximum power, current and voltage at maximum power article. The program allows you to export the measured values to a text file. In the last chapter of this work is made control measurements of three samples of monocrystal photovoltaic cell by the measuring workplace. The measurement is compared with the reference device Solar Cell Tester.
|
|
|
Photovoltaic system with sun-tracker
Riabov, Mikhail ; Křivík, Petr (referee) ; Vaněk, Jiří (advisor)
The aim of the bachelor thesis " Model of photovoltaic system with solar tracker“ is to apprise with principles of operation of solar systems. We will focus on the tracking system, which is turning itself depending on the position of the sun. In the theoretical part we will describe the principle of operation of photovoltaic cells and solar systems. In the practical part of the work we will compare the parameters of the static and dynamic solar system and make decision, which of these systems is more profitable for use.
|
|
|
Photovoltaic System With Sun-Tracker
Riabov, Mikhail
The aim of the semestral work "Photovoltaic system with sun-tracker“ is to apprise with principles of operation of solar systems. We will focus on the tracking system, which is turning itself depending on the position of the sun. In the theoretical part we will describe the principle of operation of photovoltaic cells and solar systems. In the practical part of the work we will compare the parameters of the static and dynamic solar system and make decision, which of these systems is more profitable for use.
|
|
|
Photovoltaic system with sun-tracker
Riabov, Mikhail ; Křivík, Petr (referee) ; Vaněk, Jiří (advisor)
The aim of the bachelor thesis " Model of photovoltaic system with solar tracker“ is to apprise with principles of operation of solar systems. We will focus on the tracking system, which is turning itself depending on the position of the sun. In the theoretical part we will describe the principle of operation of photovoltaic cells and solar systems. In the practical part of the work we will compare the parameters of the static and dynamic solar system and make decision, which of these systems is more profitable for use.
|
|
|
Design of VA-characteristic meter
Štěpnička, Martin ; Szabó, Zoltán (referee) ; Steinbauer, Miloslav (advisor)
The thesis describes the design of a measuring device volt-ampere characteristics of PN junction suitable for measuring characteristics of stabilizing diodes. Describes the basic principle of PN junction and related events. Part of the text discusses how to minimize the adverse parasitic effects. Furthermore, the proposal deals with an AC adapter suitable for this device. With that analyzes marginally rectifiers, stabilizers and filters. The following is a description of the device for measurement, principle of communication with the computer and the method of data processing. The annex contains schematic design, printed circuit boards and part list.
|
|
| |
guest ::
