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  • Author or Editor: Miklós Kuczmann x
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This paper deals with the numerical analysis of a vector hysteresis measurement system, which is under construction in the laboratory. The aim is to build up a single sheet tester with round shaped specimen. The goal of simulations is to find out the main features of the measurement system. The 3D finite element method (FEM) with tetrahedral mesh developed in the laboratory has been applied for investigations of the nonlinear eddy current field problem. The characteristic of the magnetic material has been taken into account by the isotropic vector Preisach model. The nonlinearity has been handled by the polarization method and the nonlinear system of equations has been solved by the fixed-point technique. The first results are presented in this work.

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The aim of the present paper is to show a simple, but well applicable solution to generate arbitrary waveform of magnetic flux density in scalar hysteresis measurements. The paper deals with a possible realization of eliminating the effect of measurement noise as well. First, the measured signals have been transformed into the frequency domain, and after applying digital filter, the spectrum of the filtered signals have been transformed back to the time domain. The proposed technique results in an accurate noise removal algorithm. The paper illustrates a fast controlling algorithm applying the inverse of the actually measured hysteresis loop, and another proportional one to measure any distorted flux pattern. Developing the mentioned algorithms aims the controlling of a more complicated phenomenon, i.e. measuring the vector hysteresis characteristics.

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The paper deals with the numerical analysis of a vector hysteresis measurement system, which is now under construction. The measurement set up consists of an induction motor whose rotor has been removed, and its windings have been replaced to a special two phases one, which can generate a homogeneous magnetic field inside the motor. A round shaped specimen can be inserted into the arrangement. The two orthogonal components of the magnetic field intensity and of the magnetic flux density vectors can be measured by H -coils and B -coils, respectively. The Finite Element Method (FEM) with the T, Φ-Φ potential formulation has been applied in the simulations. The vector hysteresis property of the specimen has been approximated by the isotropic vector Preisach model, finally the nonlinear problem has been solved by the convergent fixed point technique. The aim of the present work is to focus on the design aspects of this kind of measurement system.

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The numerical analysis or design of an arrangement, which require electromagnetic field calculation, can be characterized by the electric and magnetic field intensities and flux densities. For determination of these field quantities in the electromagnetic field, one method is to find the solution of the partial differential equations of the field quantities under prescribed boundary conditions obtained from Maxwell’s equations. The Finite Element Method (FEM) is a possible technique to solve partial differential equations, which is based on the weak form of the weighted residual method. The paper presents some potential formulations, which can be used for solving static magnetic field problems and eddy current field problems with the help of FEM. Some examples are also presented at the second part of the paper.

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The paper presents and compares three potential formulations to solve nonlinear static magnetic field problems by applying the fixed-point technique and the Newton-Raphson scheme. Nonlinear characteristics have been handled by the polarization method in the two algorithms. The proposed combination of Newton-Raphson scheme and the polarization formulation result in a very effective nonlinear solver, because only the derivate of the characteristics, i.e. only the permeability or the reluctivity has to be used. That is why, this method can be prosperous to solve nonlinear problems with hysteresis, and it is faster than the classical fixed-point method.

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The paper presents a rotational single sheet tester, which can be used to measure vector hysteresis characteristics using specimen with round shape. The measured hysteresis characteristics in the two orthogonal directions present the uniaxial anisotropy of the material under test, which has been handled by the Fourier expansion of the measured Everett functions. The Fourier coefficients of the unknown vector 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. Comparisons between measured and simulated data show acceptable results.

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A comprehensive analysis of the finite element method based lamination modeling has been performed and the results are presented in this paper. The simulations are made in two subsequent steps. In the first step, the approximate magnetic field distribution inside the material with linear characteristics is determined assuming a bulk material having anisotropic conductivity and laminates are not taken into account. In the second step, the eddy current field inside the individual laminates is modeled. The boundary conditions of any individual sheets are obtained from the bulk model. The paper presents the advantages and the drawbacks of the applicable potential formulations. Results are compared with the quasi-static electromagnetic field obtained from a reference solution taking account of each laminate.

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The paper presents a modified version of the T.E.A.M. Problem No. 32 of the Compumag Society. The original problem is a measurement arrangement to study the magnetic flux density distribution inside an EI ferrite core. A finite element simulation of the device in the frame of COMSOL Multiphysics using the A -formulation has been worked out. First, the device has been realized, and a LabVIEW program has been implemented to measure the waveform of the voltage of B-coils. The geometry and the solution of the problem have been implemented in the frame of COMSOL Multiphysics, to calculate magnetic flux density at the points, where B-coils are on the core.

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The paper presents simulation results of a two-dimensional permanent magnet synchronous motor, which were calculated by the help of the Infolytica MotorSolve and of the COMSOL Multiphysics, as well. The simulation results were compared with each other focusing on the torque, the magnetic flux density and the magnetic potential of the permanent magnet synchronous motor.

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The aim of this paper is to give a unified comparison of non-overlapping domain decomposition methods for solving magnetic field problems. The methods under investigation are the Schur complement method and the Lagrange multiplier based finite element tearing and interconnecting method, and their solvers. The performance of these methods has been investigated in detail for two-dimensional magnetic field problems as case studies.

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