National Repository of Grey Literature 16 records found  1 - 10next  jump to record: Search took 0.00 seconds. 
Losses Analysis in Electric Machines under Special Conditions
Bulín, Tomáš ; Rafajdus, Pavol (referee) ; Skala, Bohumil (referee) ; Ondrůšek, Čestmír (advisor)
This thesis deals with the analysis of magnetic losses in electrical machines and the possibilities of their measurement. Magnetically soft and hard materials are very prone to changing magnetic properties. They can be changed simply by changing the temperature of the material or different stresses induced in the material, resulting in different results. These changes are important to keep in mind when an electric machine is being designed. The original parameters of the affected materials can be restored by annealing or grinding. These methods release the induced stresses within the material. Due to these effects, it is also important to know how to measure magnetic parameters. Each way has its own specifics and has a certain error of the measurement. When the machines for higher efficiency, rpm or higher temperatures are designed, it is advisable to know how their magnetic properties changed. This thesis deals with the properties of different materials, their measurements and finally simulation of the chosen electric machine with the application of the measured results.
CHANGES IN ELECTRICAL STEEL SHEETS INDUCED BY HEAT TREATMENT
Bulín, Tomáš ; Švábenská, Eva ; Hapla, Miroslav ; Ondrušek, C. ; Schneeweiss, Oldřich
Surface coating of electrical steel sheets is very important due to minimizing eddy current losses in electrical machines. The quality of coating can differ according to the composition. The coating layer has limited heat stability and after crossing of the guaranteed temperature it can be significantly degraded and its insulation properties may change importantly. The aim of this study is to describe changes in parameters of magnetic behavior of the non-oriented Si electrical steel sheet due to degradation of the coating by annealing in air. The parameters were acquired from the measuring of magnetic hysteresis loops on two types of samples with different excitation. The basic information on structure was obtained by optical microscopy. Acquired data are compared between samples with the damaged coating layer by annealing and the original coating layer. The results are discussed from the point of view of the possibility of using sheets with damaged insulation in electrical machines.
CHANGES IN ELECTRICAL STEEL SHEETS INDUCED BY HEAT TREATMENT
Bulín, Tomáš ; Švábenská, Eva ; Hapla, Miroslav ; Ondrušek, C. ; Schneeweiss, Oldřich
Surface coating of electrical steel sheets is very important due to minimizing eddy current losses in electrical machines. The quality of coating can differ according to the composition. The coating layer has limited heat stability and after crossing of the guaranteed temperature it can be significantly degraded and its insulation properties may change importantly. The aim of this study is to describe changes in parameters of magnetic behavior of the non-oriented Si electrical steel sheet due to degradation of the coating by annealing in air. The parameters were acquired from the measuring of magnetic hysteresis loops on two types of samples with different excitation. The basic information on structure was obtained by optical microscopy. Acquired data are compared between samples with the damaged coating layer by annealing and the original coating layer. The results are discussed from the point of view of the possibility of using sheets with damaged insulation in electrical machines.
Production Comparison of High Voltage Winding of Dry Transformers
Mrajca, Miroslav ; Bulín, Tomáš (referee) ; Ondrůšek, Čestmír (advisor)
This bachelor thesis deals with the history, importance, usage, construction and principle of the operation of transformers. The thesis also focuses on the detailed description of the parts which the dry power transformer is composed from, as well as the description of their manufactory and following assembly into one unit. The thesis contains the comparison of different technologies of manufactory of higher voltage winding and magnetic circuit. The thesis contains a process of design of the dry transformer with an example of calculation. The output is a comparison of different high voltage winding technologies in terms of production costs and winding factor.
Problems with Magnetic Measurement of 41CrMo4 Steel
Bulín, Tomáš
This article deals with a problem of measuring a soft magnetic material with different geometrical dimensions. Steel 41CrMo4 was chosen as tested solid material. Two geometrical dimensions of this material were measured from the view of magnetic properties and compared each other. It is very difficult to determine proper commutation and hysteresis curve because eddy currents occur in every solid material.
Axial magnetic flux generator for small hydro power plant
Tauš, Michal ; Bulín, Tomáš (referee) ; Ondrůšek, Čestmír (advisor)
This bachelor thesis deals with a design of axial permanent magnet generator. The first part is devoted to the overview of machines driven by permanent magnets and the comparison of axial machines. In the next part the thesis deals with the design of the machine with axial magnetic flux based on the specified parameters. In the last part, the real properties are verified by ANSYS Maxwell simulations.
Design of synchronous spoke motor
Kopecký, Jan ; Bulín, Tomáš (referee) ; Knebl, Ladislav (advisor)
This thesis is focused mainly on the theoretical research of permanent magnet synchronous motors. In addition, various methods of designing the motor‘s magnetic circuit are discussed and their advantages and disadvantages are compared. The reluctance network method is analyzed more thorough, because this method is used for motor designing process. In the last part the results obtained by reluctance network are compared with the results evaluated by finite element method.
Design of linear motor with permanent magnets
Čech, Jan ; Bulín, Tomáš (referee) ; Knebl, Ladislav (advisor)
The first part of this thesis deals with the study of linear motors. The introduction of the thesis deals with the brief description of the linear motor, including its accessories. This part explains principle of linear motors, their general advantages and disadvantages. The next section contains an overview and division of the currently used linear motors. Each type of currently used linear motors is briefly introduced and also its principle and characteristics are described, including its specific application. The second part of the thesis deals with the design of an equivalent magnetic circuit model of a linear iron-core linear motor. Hereafter, the proposed design will be used to simulate the distribution of magnetic flux in the linear motor. The evaluated flux-density distribution in the air gap is later compared with the results obtained with finite element method. The thrust is then calculated from the flux-density and the estimated value is compared with the value listed in datasheet.
Nanoscale phases on surface Fe-6Si magnetic sheets
Švábenská, Eva ; Roupcová, Pavla ; Král, Lubomír ; Bulín, Tomáš ; Vondráček, Martin ; Foldyna, Josef ; Čechal, J. ; Schneeweiss, Oldřich
Analysis of the nanoscale phases which appear on the surface Fe-6Si samples were carried out after the various treatments – grinding and etching, annealing, and water jet abrasion. The basic information on structure, chemical and phase composition was obtained by X-Ray Powder Diffraction (XRD), Scanning Electron Microscopy with EDX, Glow Discharge Optical Emission Spectrometry (GDOES), Mössbauer Spectroscopy and X-ray Photoelectron Spectrometry (XPS). The results show high stability of the surface phase composition after the mechanical and heat treatments. Results obtained from the surface analysis in micrometer depth (XRD, EDX, GDOES) do not show any changes after the different treatments. Iron oxides were detected in XPS and conversion electron Mössbauer spectra (CEMS) which analyze the surface composition in a nanometer scale. In addition to, fine changes in atomic ordering on the surface can be observed after mechanical and heat treatments in the CEMS spectra.
Measurement of the magnetic properties of materials using LabVIEW
Šolc, Martin ; Bulín, Tomáš (referee) ; Huzlík, Rostislav (advisor)
In this thesis LabVIEW program and its development environment is described. After that the most used current transducers, their working principles and their properties are analyzed. Next part is dedicated to curves of magnetic hysteresis of ferromagnetic materials. Practical part of bachelor´s thesis is dedicated to measuring BH curves of torroidal core transformer. The measuring was made possible by LabVIEW program, using digital integration in LabVIEW, analog integration with RC cell, voltage converter and current transducer ITN 12-P Ultrastab. In the last part of the bachelor´s thesis I evaluate the measurements.

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