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Electromagnetic analysis and modeling of a solid rotor induction machine
Bílek, Vladimír ; Vítek, Ondřej (referee) ; Bárta, Jan (advisor)
Tato diplomová práce se zabývá elektromagnetickou analýzou a modelováním asynchronního stroje s plným rotorem. Tato práce tedy zahrnuje literární rešerši na téma vysokootáčkových elektrických strojů s porovnáním s klasickými elektrickými stroji s převodovkou a popisem jejich výhod či nevýhod, rozdělení vysokootáčkových elektrických strojů s plnými rotory a srovnání jejich výhod či nevýhod, kde se tato práce nejvíce soustřeďuje na vysokootáčkové asynchronní stroje s plnými rotory a jejich použití v průmyslu. Dále se tato práce zabývá metodami výpočtu elektrických asynchronních strojů s plnými rotory. Proto jsou zde uvedeny a popsány metody výpočtu stroje mezi které patří analytické metody i metoda konečných prvků. Vzhledem k povaze elektrických strojů s plnými rotory je hlavně kladen důraz v této práci na výpočet stroje pomocí metody konečných prvků ve 2D prostoru s využitím korekčních činitelů konců plných rotorů, které jsou zde velmi detailně popsány a rozděleny. Na základě dostupné literatury je vypočítaný elektrický stroj s plným rotorem pomocí MKP analýzy. Elektromagnetický výpočet stroje je automatizován pomocí skriptu vytvořeného v Pythonu. Dalším hlavním cílem této práce je popis tzv. náhradních modelů, uvedení jejich výhod či nevýhod, použití v jiných průmyslových odvětvích a hlavně použití náhradních modelů na elektrický stroj s plným rotorem. S využitím náhradních modelů je dále optimalizovaný vybraný asynchronní stroj s plným rotorem a to pomocí programů SymSpace a Optimizer. Pro samotnou optimalizaci byly uvažovány 3 návrhy stroje, které byly na závěr mezi sebou porovnány a to hlavně z hlediska jejich elektromagnetického výkonu.
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Effect of voltage variant of a frequency converter on asynchronous motor parameters
Pavlas, Michal ; Bílek, Vladimír (referee) ; Bárta, Jan (advisor)
This bachelor thesis is focused on literature researches, dealing with the properties of controlled drives with asynchronous machines. The work describes the possibility of operation of a three-phase asynchronous machine directly powered from a single-phase network without a frequency converter. In the next part, the research is focused on a theme dealing with the influence of harmonics of the converter on the parameters of an asynchronous motor. Subsequently, specific test methods for determining the losses and efficiencies of AC motors powered by frequency converters are described on the basis of the IEC 60034-2-3 standard. The last part of this bachelor thesis is devoted to the assessment of the influence of the voltage variant of the frequency converter on the parameters of the asynchronous motor.
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Electromagnetic calculation of an induction machine using an open source program
Bílek, Vladimír ; Mach, Martin (referee) ; Bárta, Jan (advisor)
This bachelor thesis deals with issues of finite element method and its use for electromagnetic calculation of induction machine. The first part of the thesis deals in details about finite elementh method, where the thesis describes the procedure of calculation of electromagnetic model and its use in simulation software. The second part contains and compares the list of paid and open-source simulation programs. The third part describes the creation of the specified electromagnetic model. The fourth part of thesis represents program ELMER, program's posibilites and how to set up scripts for simulation. The fifth part compares simulation results with measurments on real induction machine. The last part is the overall evalution of the thesis.
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Comparison of machine learning training sampling schemes for induction machine modeling
Bílek, Vladimír
The aim of the paper is to demonstrate the modelingof an induction machine using a chosen machine learningtechnique, followed by a comparison of the training samplingschemes for this technique. A simple 3-phase induction machinewith an axially slitted solid rotor has been selected for the casestudy, where FEM-based program Ansys Electronics Desktophas been used for its calculation. A total of 3 training schemeswere considered and compared with each other for the machinelearning technique. Some of the comparison results are given anddiscussed at the end of this paper. The described methodologycan be used to accelerate the design and optimization of any typeof electrical machine.
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Torque-speed characteristic optimization of an induction machine using machine learning
Bártková, Tereza ; Klíma, Petr (referee) ; Bílek, Vladimír (advisor)
Purpose of this work is optimization of given electrical machine based on combination of selected methods. The first chapter introduces machine learning in general. Its fundamental approaches and typical problems are analyzed together with some of the actual algorithms. The topic of optimization is introduced in the following chapter - its purpose and explanation of its concepts. The limitations we face while optimizing designs are demonstrated on two basic methods. Several popular algorithms are described, that could possibly be used in the context of electrical machines' optimization. One of the goals is reached in the third chapter - the choice of machine learning method in combination with optimization algorithm. The fourth chapter deals with matters of creating the induction machine geometry and subsequently its electromagnetic model for the following analysis. Details of geometric dimensions and electromagnetic parameters are introduced as well as calculation of end winding leakage inductance, one phase winding resistance and resistance and inductance between bars. There is also a brief description of the tools used for creating the model. The next chapter presents results of the electromagnetic analysis of the model. The process of creation on surrogate models of a given machine is described in the sixth chapter. It comprises the sensitivity analysis, creation of the initial training data and active learning. Next chapter deals with the optimization of the given machine utilizing surrogate models and selected optimization algorithms. The last chapter compares original machines' characteristics to those of optimized geometries.
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Effect of voltage variant of a frequency converter on asynchronous motor parameters
Pavlas, Michal ; Bílek, Vladimír (referee) ; Bárta, Jan (advisor)
This bachelor thesis is focused on literature researches, dealing with the properties of controlled drives with asynchronous machines. The work describes the possibility of operation of a three-phase asynchronous machine directly powered from a single-phase network without a frequency converter. In the next part, the research is focused on a theme dealing with the influence of harmonics of the converter on the parameters of an asynchronous motor. Subsequently, specific test methods for determining the losses and efficiencies of AC motors powered by frequency converters are described on the basis of the IEC 60034-2-3 standard. The last part of this bachelor thesis is devoted to the assessment of the influence of the voltage variant of the frequency converter on the parameters of the asynchronous motor.
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Pupils' Problems and Mistakes when Manipulating Algebraic Expressions
Bílek, Vladimír ; Vondrová, Naďa (advisor) ; Žalská, Jana (referee)
The thesis focuses on mistakes and problems in manipulations with the algebraic expressions occurring to pupils at the second level of Elementary school. The thesis is divided into a theoretical and experimental part. The theoretical part contains description of manipulations with algebraic expressions, selected results of international comparative surveys, and an analysis of related foreign research. Analysis of three series of textbooks, according to which pupils involved in the experimental project are taught, is essential for understanding of possible origins of their mistakes. The classification of mistakes in manipulations with algebraic expressions is included. At the core of the work is the experimental part aiming to identify problems and mistakes of pupils when manipulating and working with algebraic expressions. The participants of the research consisted of six third-grade pupils of an eight-year Grammar school (13-14 years old) and eight ninth-grade pupils of an Elementary school (14-15 years old). Test used for my experiment came from the GA ČR project Critical parts of mathematics in primary school. The investigation was carried out individually with each pupil by the method of monitoring clinical interviews over the solution of the test tasks. The obtained data was qualitatively...
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Floor function and fractional part of the real number
Bílek, Vladimír ; Novotná, Jarmila (advisor) ; Pilous, Derek (referee)
The aim of my bachelor thesis is to acquaint the reader with the floor function, ceiling functions and with fractional part of the real number, and show the feasibility of selected equations of one unknown that contains the floor functions of the real number. In the introductory part of my thesis, necessary concepts, notations and definitions of these functions are defined. The main part of the work is devoted to a description of strategies for finding solutions to following four types of equations: , and . Derived general procedure for solving the first equation and a description of the strategy for finding solutions to the remaining three equations are the greatest benefits of my thesis. The procedures are demonstrated by examples in each chapter. The final section covers some types of unsolved problems from different areas of mathematics concerning this topic.
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Sensitivity Analysis Of An Induction Machine With A Solid Rotor
Bílek, Vladimír
The main focus of this paper is to show the results of sensitivity analysis of an inductionmachine with a solid rotor. For the case study, a three-phase induction machine with a squirrel cage ischosen. However, the rotor of this machine is replaced with an axially slitted solid rotor. The electromagneticmodel is analyzed by transient simulation using the FEM-based program Ansys maxwell.For the sensitivity analysis, several parameters are changed in a wide range to see the difference inthe machine overall performance. Some of the results of these simulations are shown and discussedat the end of this paper.
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