Wyniki 1-10 spośród 27 dla zapytania: authorDesc:"Miklós KUCZMANN"

Nodal and Edge Finite Element Analysis of Eddy Current Field Problems

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Eddy current field problems can be solved by different potential formulations based on the "quasi-static" Maxwell's equations. The potential formulations are obtained using a vector potential and a scalar potential, the most widely used techniques are the A,V-A, the T,Φ-Φ formulations and their combinations. Vector potentials can be approximated by nodal or edge finite elem[...]

The polarization method combined with the Newton-Raphson technique in magnetostatic field problems

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Nonlinear magnetic field problems can be solved by using the polarization method. After applying the Finite Element Method (FEM), a system of nonlinear equations can be derived, which can only be solved by iterative techniques. The fixed point iteration scheme and the Newton- Raphson technique are the most widely used algorithms to solve nonlinear equations. The first is known as a convergent, b[...]

Identification of Dynamic Hysteresis Model

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The paper presents a measurement system which can be used to prepare measured data to identify the Preisach hysteresis model. The identification is based on the Everett function. A fast and memory efficient realization of the model will be shown which is very useful in numerical field analysis techniques. The dynamic extension of the static model is based on the loss separation formula, and the measured excess magnetic field has been approximated by a feed-forward type neural network. The developed model has been inserted into a finite element procedure. Streszczenie. W artykule zaprezentowano system pomiarowy do przygotowania danych, do identyfikacjj modelu Preisacha pętli histerezy. Identyfikacja oparta jest na funkcji Everetta. Pokazana jest szybka i pamięciowo efektywna metoda ide[...]

Vector Hysteresis Measurement and Simulation

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The paper presents a Preisach model of hysteresis to simulate the vector hysteresis properties of ferromagnetic materials. The vector behavior has been studied using a single sheet tester with a round shaped specimen at low frequency, and the magnetic flux density vector has been controlled. An inverse vector Preisach hysteresis model has been developed and identified by applying the measured data. Finally, the inverse model has been inserted into a finite element procedure to study numerically the measurement system. Streszczenie. Artykuł przedstawia model Preisacha pętli histerezy służący do symulacji właściwości wektora histerezy w materiałach magnetycznych. Badanie wektora histerezy prowadzone jest przy użyciu SST (single sheet tester) dla nislich częstotliwości ze sterowaniem we[...]

Nonlinearity in the finite element simulations

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The paper presents the four possible nonlinear schemes to solve nonlinear static magnetic field problems and eddy current field problems by the fixed point technique while using the polarization formulation to linearize the nonlinear curve of the constitutive law of ferromagnetic materials. The finite element method (FEM) has been chosen as a numerical tool to present the applicability of the technique. Streszczenie. Artykuł przedstawia cztery możliwe nieliniowe schematy rozwiązywania nieliniowych problemów pola magnetycznego statycznego i pola prądów wirowych . Przydatność opracowanych modeli została numerycznie wykazana przy użyciu MES.(Nieliniowość w symulacjach elementami skończonymi) Keywords: FEM, nonlinear constitutive law, polarization formulation, fixed point method. Słowa kluczowe: MES, nieliniowe prawa konstytutywne, sformułowanie polaryzacyjne, metoda punktu ustalonego. Introduction The paper presents the well known fixed point technique [1] to solve nonlinear static magnetic field problems and eddy current field problems in the presence of nonlinear characteristics of ferromagnetic materials. Simple functions as well as more powerful models, like the Preisach model, are introduced in the fixed point scheme. Maxwell’s equations can be represented by the help of potentials. Scalar potentials and vector potentials can be used to calculate the electromagnetic field quantities and to decrease the number of unknown vector functions. Partial differential equations can be obtained after the introduction of potentials which solution can be obtained by the help of numerical techniques, such as the finite element method (FEM). FEM approximates the true solution of a problem using a discretization in space and in time. The insertion of nonlinear characteristics into numerical techniques can be worked out by the use of the polarization formulation which results in a linearized form of the nonlinear equations. The obtained e[...]

Measurement and simulation of vector hysteresis

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The paper presents a rotational single sheet tester (RSST) which can be used to measure vector hysteresis characteristics inside a specimen with round shape. The measured hysteresis characteristics in the orthogonal directions presents uniaxial anisotropy. It has been handled by the Fourier expansion of the measured Everett functions. The Fourier coefficients of the unknown Everett function have been identified by the modification of a previously implemented algorithm. In the identification task linearly and circularly polarized measured data have been taken into account. Streszczenie. Artykuł przedstawia obrotowy tester jedno-arkuszowy (RSST), który może być wykorzystany do pomiaru wektora histerezy w obiekcie o kształcie okrągłym. Mierzona w prostopadłych kierunkach pętla histerezy posiada jednoosiową anizotropię. Problem został rozwiązany przez użycie rozwinięcia Fouriera pomierzonych funkcji Everetta. Współczynniki Fouriera nieznanej funkcji Everetta zostały zidentyfikowane poprzez modyfikację zaimplementowanego algorytmu. W zadaniu identyfikacji wzięto pod uwagę liniowo i kołowo spolaryzowane dane pomiarowe. (Pomiar i symulacja wektora histerezy) Keywords: Everett function, Preisach model, Vector hysteresis characteristics. Słowa kluczowe: funkcja Everetta, model Preisacha, charakterystyka wektora histerezy Introduction Different types of single sheet testers have been designed and manufactured to measure vector hysteresis properties of soft magnetic materials [1-10]. The Rotational Single Sheet Tester with a specimen with round shape (R-RSST) has been used in this study [9-10]. The Preisach model of hysteresis is the most widely applied simulation technique to approximate measured hysteresis curves [11,12]. The vector Preisach model is able to simulate vector behaviors of the field quantities inside the materials under test [11], i.e. the phase lag between the magnetic field intensity vector and the magnetic flux density vecto[...]

Feeding models of wire antennas

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Antenna parameters (e.g. input impedance, radiation pattern) can be measured in Full Anechoic Chambers (FAC). The simulated input impedance is depending on the applied feed model. The most frequently used models are the current probe model, the voltage gap generator, the magnetic frill generator and the waveguide port which are presented in this paper focusing on a simple example, a monopole antenna situated above a ground plane. The Finite Element Method (FEM) has been used in the numerical field analysis. Streszczenie. Parametry anteny (np. impedancja wejściowa, własności promieniowania)mogą być zmierzone w komorze bezodbiciowej. Zasymulowana impedancja wejściowa zależy od modelu zasilania anteny. Najczęściej spotykane modele: model sondy prądowej, generator napięciowy ze szczeliną, frill generator, oraz falowód, pokazane są w artykule z naciskiem na prosty przykład anteny jednobiegunowej umieszczonej nad płaszczyzną gruntu. Metod elementów skończonych została użyta w analizie numerycznej. (Modele zasilania anten obwodowych) Keywords: antenna feeding, antenna parameters, finite element method. Słowa kluczowe: zasilanie anteny, parametry anteny, metoda elementów skończonych Introduction The most important measured parameters of an antenna are the input impedance and the radiation pattern. Other parameters, such as the reflection coefficient or the voltage standing-wave ratio can be calculated from the input impedance, the directivity as well as the gain can be obtained from the radiation pattern. The simulated input impedance is depending on the applied feed model that is why it is very important to know the advantages and the disadvantages of the feeding models. The most frequently used models are the current probe model, the voltage gap generator, the magnetic frill generator and the waveguide port. This paper presents the above mentioned approaches through a monopole antenna situated above a ground plane. The Finite Element Met[...]

Parallel Finite Element Method

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The paper presents the domain decomposition method as a tool to cut the finite element mesh into smaller sub-meshes. Smaller mass matrices can be assembled and solved in a parallel way, i.e. the solution time can be decreased by this method. The finite element method has been chosen as a numerical tool to present the applicability of the technique. Streszczenie. Artykuł przedstawia metodę dekompozycji obszaru jako narzędzie do podzielenie siatki elementów skończonych na mniejsze obszary. Mniejsze macierze układu mogą być składane rozwiązywane w sposób równoległy - czas rozwiązywania może być w tym podejściu zmniejszony. Do przedstawienia skuteczności metody została wybrana metoda elementów skończonych, (Równoległa metoda elementów skończonych) Keywords: finite element method, parallel computing, domain decomposition method. Słowa kluczowe: metoda elementów skończonych, obliczenia równoległe, metoda dekompozycji obszaru. Introduction The finite element method (FEM) is a numerical tool to solve electromagnetic field problems [1-4]. It is based on the weak formulation of the partial differential equations obtained from Maxwell’s equations and on the finite element discretization of the geometry of the problem to be analyzed. The system of linear equations can be solved by specialized solvers according to the symmetry of the sparse mass matrix. Anyway, the solution of three dimensional problems with a huge number of unknowns can be very time consuming. The finite element mesh can be decomposed into smaller sub-meshes with equal number of finite elements (Fig. 1). These are also called subdomains. The submeshes can be handled by the independent processors of a supercomputer or the independent computers of a computer grid. The equations according to the sub-meshes can be assembled in an independent, i.e. parallel way. There are nodes and edges shared by two or more subdomains. The number of such nodes and edges should be decrea[...]

Temperature and frequency dependent Preisach model DOI:10.15199/48.2018.04.02

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Ferromagnetic hysteresis is present in the operation of most electrical engineering equipments, e.g. electric motors, transformers, components for power electronics and so on. The phenomena occurs power losses in these devices that must be taken into account during the design phase. Accurate power prediction can only be performed by accurate models. Preisach modeling and Jiles-Atherton techniques are the most fruitful techniques to take hysteresis into account [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12]. In this paper, taking the temperature effects into consideration at different frequency of the source field is presented. Measured hysteresis loops depending on the frequency and the temperature are shown and compared with the identified extended Preisach model. The measurement system The detailed description of the measurement system can be found in [13, 14]. Here a short presentation is given. The block diagram of the developed measurement system is shown in Fig. 1. Fig. 2 presents a photograph about the setup. Hysteresis characteristics have been measured using a toroidal shape core made of laminated soft magnetic material (M250-35A manufactured by the ArcerolMittal company). The magnetic field inside the specimen has been generated by the current i(t) flowing in the primary coil with Np = 94 turns. The arbitrary waveform of current has been generated by LabVIEW functions. The time variation of the magnetic field intensity results in a time varying magnetic flux (t) inside the specimen, finally the effect of this flux can be measured by the secondary coil wound on the core. The secondary coil has Ns = 121 turns which output is the induced voltage u(t). The magnetic field intensity is calculated from the current of the primary coil: (1)     p , N i t H t l  where l = 163mm is the mean length of the core. The magnetic flux density is obtained from the induced voltage of t[...]

Nonlinear Simulation of a Magnetic Flux Leakage Measurement System

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The paper presents the building up of a computer controlled measurement system based on National Instruments Data Acquisition card and National Instruments LabVIEW software package. The aim of this research is to detect surface cracks on steels by applying a Magnetic Flux Leakage (MFL) testing method. First, a finite element based procedure has been implemented to analyze the arrangement. One im[...]

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