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Analysis of damage to the rotor bars of induction machines
Henzel, Roman ; Michailidis, Petr (referee) ; Skalka, Miroslav (advisor)
This bachelor thesis deals with disorders of induction machines with focus on the failure or damage to the rotor bars or end rings. The work includes a literature research of the low resistance measurement, which can be used to determine the rotor bar resistance of the squirrel cage induction machine. The experimental measurement of the analyzed motor with the following conditions (short-circuit, no-load and load) is also includes. The magnetic model of the machine was described and created in MAXWELL and results were compared with the LabVIEW software (in order to verify the accuracy of the particular simulation). Analysis results evaluation of three phase squirrel cage induction machine with broken rotor bars was done.
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Impedance measurement of lead-acid accumulator properties
Vaculík, Sebastian ; Neoral, Jiří (referee) ; Abraham, Pavel (advisor)
This work deals with the new and unique four-point method measurement of the impedance characteristics for experimental positive electrode. The theoretical part provides a short introduction to the electrochemical power sources, including the lead-acid batteries, which were used for measurement. Furthermore, there is description of the principle of electrochemical impedance spectroscopy and analysis of obtained data by using the equivalent circuit, consisting of passive components. The experimental section is devoted to the description of the device, which is used for realization of connection of electrodes with Potenciostat VSP, and program which is used for the simplification of processing of results. The main aim of this bachelor thesis is to get better understanding of lead-acid accumulators and impedance measurements. At practical part of the thesis I performed first measurements by two-step method based on electrochemical impedance spectroscopy.
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Traction Drives with Asynchronous Motors
Běloušek, Josef ; Skala, Bohumil (referee) ; Richter, Aleš (referee) ; Patočka, Miroslav (advisor)
The first part of this work is devoted to the design of a traction asynchronous motor. The second part focuses on the developed method of the equivalent circuit parameters identification of the asynchronous motor in the form of -network. It is explained here that the equivalent circuit in the shape of a -network, alternatively of an inverse 'I-network, is exactly equivalent and fully-fledged to a T-network, although one of two stray inductances is formally missing. Furthermore, the relationships for the conversions of the T-network parameters to the -network parameters and back, and of the T-network to the inverse 'I-network and back are found. The third part deals with the calculation of the torque and the current characteristics of the asynchronous motor. A sensitive analysis of the torque characteristic is carried out on the individual parameters of the equivalent circuit of the asynchronous motor in the form of a -network and a method of the measurement by means of a flywheel is used for the torque characteristic measurement of the asynchronous motor. The fourth part focuses on the verification of the identified -network parameters in the Matlab-model of the traction drive.
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Mechanical Torque Analysis of Induction Machine Based on Magnetic Circuit Saturation
Skalka, Miroslav ; Bendl,, Jiří (referee) ; Voženílek, Petr (referee) ; Ondrůšek, Čestmír (advisor)
e main goal of this thesis is mechanical torque analysis of induction machine based on magnetic circuit saturation, oversaturated areas classification and the possibility of oversaturated areas reduction of their influence on machine properties. Whole problem is solved by finite element method in ANSYS program. Work is divided into the description and creating of electromagnetic model, a method of the induction machine equivalent circuit parameters determination, the electromagnetic field calculation by finite element method, experimental measurement using LabVIEW program with measurement accessories (PCIe card National Instruments), data processing program in DIAdem, results analysis of calculations in terms of magnetic circuit saturation, the influence of magnetic circuit material based on electromagnetic field distribution and the magnetic flux density along the air gap including spectral analysis using MATLAB and the electromagnetic torque and its parasitic torque components calculation.
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Change of voltage at LV terminals of a MV/LV power distribution transformer caused by changes in its load
Jandora, Jiří ; Bátora, Branislav (referee) ; Blažek, Vladimír (advisor)
The thesis deals with the use of distribution transformers, their integration into the electrical network, their properties, and principles and means of regulation according to changes in load. The introductory chapter is devoted mainly to the theoretical background concerning the functioning of the transformers. Even though it is not the focus of this thesis, a brief summary of their structure will be provided because it is presumed that not all the readers are familiar with this particular electrical network block and thus they should be explained how the transformer works. Then the ways of transformer regulation will be outlined. In the theoretical part, the important point for the reader is the substitution of the transformer by two-port network i.e. the equivalent circuit. The two-port network is a substitution of the connection properties by simple electric elements, which are not so problematic for further use. When dealing with the two-port networks in the chosen equivalent circuit, Blondel’s constants will be used. Blondel’s constants facilitate working with the basic network invariables of the circuit such as amperage, voltage and power. The second part of the thesis is devoted to solving a problem that involves the use of distribution transformers. The problem is as follows: there is a manufacturing plant with three transformers, each of them having rated power and nominal transformation ratio. The manufacturing plant is supplied by HV three-phase line with rated voltage and parameters given by the distribution point, where constant voltage is maintained. The task is to determine in what ways the voltage of the low voltage terminals of the transformers will change when changing the power from idling circuit to the rated load. The power factor should be constant. The method for solving this task has already been outlined in the theoretical part. The results are summed up in a simple chart completed with diagrams, which concisely describe the result of the research.
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Algorithms for the Control of the Induction Motor
Hundák, Vladimír ; Běloušek, Radim (referee) ; Patočka, Miroslav (advisor)
Hlavným cieľom tejto práce je vytvorenie simulácií rôznych algoritmov riadenia asynchrónneho motora a vzájomné porovnanie ich vlastností. Zaoberá sa taktiež možnosťami konfigurácie náhradného zapojenia na T-článok, -článok a -článok. Obsahuje jednak teoretický rozbor, a taktiež aj simulácie jednotlivých spôsobov riadenia spolu s podrobným návodom na ich realizáciu. Celkovo budú vykonané 3 simulácie – simulácia vektorového riadenia s orientáciou na rotorový tok, vektorového riadenia s orientáciou na statorový tok a simulácia takzvaného prirodzeného riadenia. Ide o úplne nový typ riadenia, ktorého autorom je vedúci tejto diplomovej práce. Jeho simulácia bola vôbec prvým pokusom o funkčnú realizáciu tohto typu riadenia.
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I-V characteristic on photovoltaic modules connected in parallel and in serial
Láník, Lukáš ; Vaněk, Jiří (referee) ; Křivík, Petr (advisor)
In mentioned theses there are described the basic tenets of the photovoltaic panels operation. There is described the progress of the photovoltaic panels. Theses is focused on the theoretical knowledges about the equivalent circuits and their aplication in the proposed simulation system. The goal of theses is to create the surroundings in the program Agilent VEE Pro 8.0 and to create the program for the simulation of the serial and paralel conjunction of the photovoltaic panels. The resultant program enables the simulation of the I – V and P – V characteristics of the real photovoltaic panels.
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Influence of shading on I-V characteristics of photovoltaic modules
Hájek, Tomáš ; Vaněk, Jiří (referee) ; Křivík, Petr (advisor)
The presented thesis is concerned with the principles of Photovoltaics. It describes the basic principles of photovoltaic panels functioning and the unique periods of their developement. The thesis is also focused on the theoretical knowledge of equivalent circuits of photovoltaic panels. The primary objective of the thesis is a project of simulation environment in the programme Agilent VEE Pro 8.0. The programme enables a simulation of I-U characteristics of real photovoltaic panels.
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Electromagnetic Field Calculation of IM for Different Equivalent Circuit Parameters
Skalka, Miroslav ; Schreier, Luděk ; Ondrůšek, Č.
This paper contains a calculation of electromagnetic field distribution of Induction machine for different equivalent circuit parameters due to the loads - each step is calculated for different rotor and stator currents. The definition of parameters and the real values of rotor and stator currents were presented on the XVI. Inter. Symposium on Electric Machinery in Prague. These data were used for a calculation of electromagnetic field distribution of Induction Machine (IM) by finite element method in ANSYS.
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