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Calculation of electrodynamic forces in 250 A circuit breaker
Görig, Michal ; Dohnal, Petr (referee) ; Valenta, Jiří (advisor)
This master’s thesis deals with the calculation of electrodynamic forces breaker BD250NE305. Main tasks in this semester project is to study the theoretical analysis of individual parts specified breakers. Processing theoretical analysis of these forces. Creating a 3D model current path and sheets quenching chamber single phase circuit breaker in Autodesk Inventor Professional 2012. Another challenge is the subsequent export the model into the simulation program ANSYS Maxwell. After simulation, the specified conditions must be processed and the results of the present work is to evaluate.
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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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Parameters identification of the asynchronous machine substituting circuit
Běloušek, Radim ; Cipín, Radoslav (referee) ; Patočka, Miroslav (advisor)
Mathematical model and substituting circuit both include several parameters, which is important to determine for a control. This work is target on identification of parameters of substitute circuit of the asynchronous machine in -network form. The work is divided into several main units. In the first of them are shown the methods of identification of asynchronous machine on the selected machine. The measuring of torque characteristic by classical way with dynamometer and by dynamically with fly-wheels is shown in the next part of this work. The final part of this work is devoted to interpretation and comparison of achieved results.
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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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Independent Traction Drive with Low-Voltage Induction Machine
Matucha, Tomáš ; Skalický, Jiří (advisor)
This work deals with creation of an exact mathematical model of a traction drive with low-voltage induction machine (28 V) which is fed from accumulators. This model was developed in MATLAB – Simulink and consists of induction machine model, inverter model and load model. Vector Control was added to models connected together. This complex model allows considering many effects into simulations. These effects are commonly neglected, although they have significant influence on drive behaviour, especially by using low-voltage machine. It is impact of magnetic circuit saturation, impact of temperature and skin effect on winding resistance, impact of inverter nonlinearities such as on-state voltage drops on switching elements, dead times and transistors switching times. The attention was paid to determination of losses in drive parts. The correctness of the model was verified at laboratory workplace established for this purpose. The laboratory drive can be controlled by a microprocessor or by using MATLAB and dSPACE application. The influence of compensations of inverter nonlinearities and DC-link voltage ripple on higher harmonics of inverter output currents was analyzed. Furthermore, the control, which decreased resistive losses, was solved.
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Simulation of Heat Transfer in Low-Voltage Switchboard MNS - Optimization of Heat Transfer into The Switchboard
Czudek, Aleš ; Maxa, Jiří (referee) ; Vyroubal, Petr (advisor)
The thesis includes diagnostics temperature field of industrial low voltage. Place of origin, flow and heat transfer are important aspects in the design of the switchgear, especially in terms of proper equipment layout. The correctness of the design of the switchgear is verified by measuring the practical temperature field during testing or in work mode. To determine the temperature profile, it is necessary to measure the temperature at various points of the switchgear, either contact or contactless method. Measurements are performed on standardized low voltage switchboards, which are located power elements. The goal is to replace costly and time-consuming field testing switchgear efficient simulation of the temperature field mathematical model developed switchboards.
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Special small induction motor
Trubák, Vojtěch ; Mach, Martin (referee) ; Hájek, Vítězslav (advisor)
This term paper is focused on theory and calculation of an induction motor with solid rotor. It is divided into six chapters, the first one being an introduction and the last being a conclusion. Second chapter is dedicated to magnetism. There is briefly description of a skin depth of a conductor and calculation method for impedance of a conductive solid. Third chapter is focused on theory of an induction machines, their construction, equivalent circuit and some of their properties. Fourth chapter is dedicated to calculation of an induction motor with solid rotor and its parameters. Fifth chapter is comparing results of calculation done in fourth chapter for an already existing motor with measured values.
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