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Magnetics, IEEE Transactions on

Issue 6 • Date November 1983

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Displaying Results 1 - 25 of 112
  • [Front cover and table of contents]

    Publication Year: 1983 , Page(s): 0
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    Freely Available from IEEE
  • A three dimensional eddy current formulation using two potentials: The magnetic vector potential and total magnetic scalar potential

    Publication Year: 1983 , Page(s): 2284 - 2287
    Cited by:  Papers (18)
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    A formulation of the three dimensional eddy current problem is presented. The magnetic vector potential is used in regions with source currents and conducting material and the total magnetic scalar potential is employed elsewhere. The continuity of the normal component of flux density and tangential component of field intensity are used to couple the two potentials on the interface between regions. The formulation leads to a symmetric system amenable to traditional solution techniques. The formulation is also valid for static problems with modification that are easily implemented. View full abstract»

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  • Complementary energy methods in the computation of electrostatic fields

    Publication Year: 1983 , Page(s): 2288 - 2291
    Cited by:  Papers (9)
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    It is shown how complementary energy methods can be applied to problems involving the calculation of electrostatic fields. The results obtained using such methods provide error bounded solutions to the system energy, and may be compared with those found through application of the conventional finite element method. To illustrate the technique the classical problem of a cylindrical tank, half filled with a charged liquid, is investigated. Comparisons are made on the basis of computer C.P.U. time, and core storage requirements, for a given degree of accuracy in total system energy. The question of local error in primary field quantities is also examined. View full abstract»

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  • Developments and experience in the fourier element method

    Publication Year: 1983 , Page(s): 2292 - 2295
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    The Fourier element method, which was developed for rapid calculation of magnetic fields in the end regions of generators, has been transformed by automatic mesh generation and algebraic manipulation. The first allows the entire geometry to be specified by the coordinates of the cross-sectional corners, presented in any order. The second, applied especially to combinations of modified Bessel functions, has divided by five the computation in setting up the stiffness matrix. Experience in applying the method to the end regions of large generators bas shown it to be easy to use, fast, and in accord with measurements. View full abstract»

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  • A spectral method for field computation

    Publication Year: 1983 , Page(s): 2296 - 2299
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    A method is presented for computating static electric and magnetic fields in which the solution is expressed as a linear combination of orthogonal basis functions. For certain configurations, this method has the advantages of eliminating the usual network of finite elements, and the solution of a large system of linear equations. View full abstract»

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  • Second order air-gap element for the dynamic finite-element analysis of the electromagnetic field in electric machines

    Publication Year: 1983 , Page(s): 2300 - 2303
    Cited by:  Papers (9)
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    To obtain a dynamic analysis for the electromagnetic field in electric rotating machines working under unbalanced conditions or supplied by non sinusoidal current we previously conceived a first order Air-Gap-Element (AGE-1). Such an element allows to keep a constant topology while the rotor is moved ; in fact the relative position of the rotor is automatically taken into account by the method [1], [2]. In the present paper a second order Air-Gap-Element (AGE-2) is developed to be consistent with second order isoparametric finite elements, using the FLUX field computing program [3] which gives more accurate calculations. Moreover the use of AGE-2 permits us to consider a solution domain corresponding to either two pole-pitches or one pole-pitch To optimize the computing time spent on solving the equation system, we used the SICCG method [4]. The paper contains the development details of the AGE-2 and examples showing the merits of the proposed model. View full abstract»

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  • A search for faster magnetic field routines for curved conductors

    Publication Year: 1983 , Page(s): 2304 - 2306
    Cited by:  Papers (7)
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    Computer packages such as GFUN3D and TOSCA, used for solving magnetostatic problems, depend on accurate and fast routines to obtain the source fields from conductors. The author compares three available algorithms for curved conductors and concludes that here is an area where further research could result in a significant saving of computing time. View full abstract»

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  • Mutually constrained partial differential and integral equations for an exterior field problem

    Publication Year: 1983 , Page(s): 2307 - 2310
    Cited by:  Papers (4)
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    A new implementation of the mutually constrained partial differential and integral equation method for the exterior 2-dimensional field problem is described. It is shown, that the method is applicable to exterior problems in an inhomogeneous medium. The inhomogeneity is considered in the finite element procedure and in boundary element method, where an adequate Green's function is applied. The temperature distribution around a three-cable system is then computed as an illustration. The eddy-current losses in the cable sheaths are calculated using the Fredholm integral equation of the second kind. View full abstract»

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  • Dual and complementary energy methods in electromagnetism

    Publication Year: 1983 , Page(s): 2311 - 2316
    Cited by:  Papers (13)
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    The use of dual and complementary variational formulations of the electromagnetic field equations is reviewed and the usefulness of such techniques explored. Particular attention is devoted to the efficient implementation of these methods in conjunction with the finite element method, and wider areas of application discussed. The use of such techniques in the development of a general structure for the field equations is outlined, and examples chosen from electrostatics, magnetostatics and time varying problems show how error bounded solutions may be achieved. View full abstract»

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  • A magnetostatic 2 1/2- dimensional field calculation program for turbogenerators

    Publication Year: 1983 , Page(s): 2317 - 2320
    Cited by:  Papers (1)
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    A finite difference program is described which calculates the magnetic field strength and flux density in a turbogenerator. The mathematical model incorporates solid or laminated iron components with non-linear permeabilities. The fields are evaluated in the r-z plane and vary periodically in the circumferential direction. The program is therefore well suited to three-dimensional end region problems. Use of the program shows how the leakage fields at the core back of a generator vary when radial cooling ducts are introduced. The importance of this for different duct configurations and generator operating voltage is evaluated. View full abstract»

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  • Finite element computation of three-dimensional electrostatic and magnetostatic field problems

    Publication Year: 1983 , Page(s): 2321 - 2324
    Cited by:  Papers (9)
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    Three-dimensional field solutions have been of considerable interest in electric machine field problems for a number of years. However, only with the advent of large scale computers, numerical analysis methods, developments in grid generation and graphics display techniques computation of three-dimensional magnetic fields has become somewhat tractable. In this paper, the progress made by the authors' company in three-dimensional field computation for scalar and vector field problems is presented. Several applications and comparison of solutions with test results, where available, and other methods are included. New computational techniques employing mixed scalar and vector formulations are introduced and comparison of results in one case with those obtained by direct methods is presented. View full abstract»

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  • Three dimensional eddy current calculation using a network method

    Publication Year: 1983 , Page(s): 2325 - 2328
    Cited by:  Papers (3)
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    First order finite element or finite difference approximations to the electric and magnetic scalar potential Poisson equations are represented by network models. The resulting linked-circuit problem is solved using nodal variables for the larger, magnetic part of the problem and mesh variables for the smaller, conducting region. This method of solution is shown to compare favourably, in terms of number of variables, with conventional finite element techniques. A surface impedance model is also presented for the solution of saturated eddy-current problems. This model uses actual iron B/H curves rather than the approximations usually employed. Both calculation methods are verified using experimental results. View full abstract»

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  • The Galerkin method of weighted residuals applied to the restricted magnetostatic scalar-potential boundary-integral equation in three dimensions

    Publication Year: 1983 , Page(s): 2329 - 2332
    Cited by:  Papers (2)
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    The point-matching method for the numerical solution of the magnetostatic scalar-potential boundary-integral equation in three dimensions has been found to suffer from limited accuracy and heavy computational costs. Experiments with the Galerkin weighted-residual scheme show significant improvements in accuracy for a given amount of computation. The formulation is restricted to the situation where currents are excluded from magnetized regions; the latter are restricted to constant permeability in this report. View full abstract»

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  • Boundary Galerkin's method for three-dimensional finite element electromagnetic field computation

    Publication Year: 1983 , Page(s): 2333 - 2336
    Cited by:  Papers (14)
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    Electromagnetic field problems are often formulated as boundary value problems in unbounded regions. For this reason, the application of conventional numerical methods, such as the finite element method, is difficult. The paper describes a new technique to circumvent this difficulty. The technique is based on the reduction of the field equations in unbounded space to equivalent boundary Galerkin's criterion. Such criterion can be combined with the volume Galerkin's criterion for regions occupied by conductors. A new quasi-finite-element discretization based on the coupled boundary/volume Galerkin's criterion is presented. View full abstract»

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  • Combination of finite and boundary elements for magnetic field analysis

    Publication Year: 1983 , Page(s): 2337 - 2339
    Cited by:  Papers (4)
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    A procedure is proposed which utilizes combined Finite Elements Method and Boundary Elements Method for magnetic field analysis. Given a region constituted by sub-regions, some of which require a dense discretization, the field analysis is carried out by using the Finite Elements Method, and the Boundary Elements Method is used for the other sub-regions which require a large discretization. The procedure is applied for studying the magnetic field due to a coil and the obtained results are compared with the values given by formulas known in the scientific literature[5]. View full abstract»

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  • Current distribution in generator main connections

    Publication Year: 1983 , Page(s): 2340 - 2343
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    Heavy copper busbars are used to carry the current between turbogenerators and generator transformers in U.K. power stations. At each end of the busbars an arrangement of many flexible braided parallel interconnectors are used between the busbars, the generator and the transformer. Within such a group of parallel interconnectors, the electromagnetic interaction induces a non-uniform current distribution as a result of which uneven heating of braids may occur. The computer-oriented technique described predicts current distributions in three-phase arrangements of parallel rectangular conductors. The paper discusses theory and distributions in three-phase arrangements. Comparison of computed and experimental results, relating to two installations, is also included. View full abstract»

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  • The H-gradient method for magnetostatic field computations

    Publication Year: 1983 , Page(s): 2344 - 2347
    Cited by:  Papers (3)
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    A new method for approximating magnetostatic field problems is given in this paper. The new method approximates the scalar potential for the magnetic intensity and is based on a volume integral formulation. The corresponding algorithm is similar to that obtained from coupled differential and boundary integral approaches. Convergence results in computations are compared with results for the usual volume integral method used in GFUN3D. View full abstract»

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  • Application of the hybrid finite element, finite difference technique to the solution of multistrand conductor problems

    Publication Year: 1983 , Page(s): 2348 - 2351
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    An algorithm for the application of a hybrid finite element, finite difference technique for the solution of linear conductor problems has been developed. This paper describes the implementation of the technique to single layer helically spiralling conductor strand geometries. Such conductor configurations occur in hollow conductors with magnetically neutral spacers. However, the technique can also be used as an approximation to the solution of expanded conductor or ACSR conductor problems if it is assumed that the core wires remain substantially magnetically neutral. The influences of conductor pitch and strand diameter or equivalent circuit parameters are illustrated by considering a number of different configurations. Theoretical samples which are physically similar to actual ACSR specimens are analyzed in order to infer the inductive role of the core strand. View full abstract»

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  • A combined finite element and loop analysis for nonlinearly interacting magnetic fields and circuits

    Publication Year: 1983 , Page(s): 2352 - 2355
    Cited by:  Papers (12)
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    A general technique is described for combining a finite element representation of a quasi-stationary nonlinear magnetic field problem and the loop equations for all circuits, moving or stationary, which interact with the field. Various power quantities associated with the field and with each independent circuit loop can be estimated directly. Methods are presented for time integration of the first-order matrix differential equation describing both field and circuits. Saturating nonlinearities are treated iteratively. In particular, a transient problem in an idealized induction motor is solved. When permitted to reach steady state this solution yields points on the torque versus slip curve for the motor. View full abstract»

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  • Application of the finite element technique to continuation problems of stationary fields

    Publication Year: 1983 , Page(s): 2356 - 2359
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    The paper deals with the application of the finite element technique to the extrapolation of stationary fields. The problem of continuation of the field potentials derived from the experimental data has been solved. The main idea is based on the application of one of the regularisation methods for solving an ill-conditioned, under- or overdetermined algebraic system of equations. Numerical calculations performed in the paper show the possible applications of the proposed method. View full abstract»

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  • BEM analysis of spectral response from finite pole-length heads on perpendicular media

    Publication Year: 1983 , Page(s): 2360 - 2363
    Cited by:  Papers (1)
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    The Boundary Element Method (BEM) is used to solve for the fields from high-permeability, finite pole-tip gapped heads, with and without a permeable layer beneath the recording medium. The underlayer enhances the recording and playback performance for perpendicular magnetization by increasing both perpendicular fields and field gradients. Reciprocity is used to find the spectral (frequency) response for both sine-wave and square-wave perpendicular magnetizations. Regions of low spectral response, geometrically induced by the finite pole-tips, are more pronounced with the underlayer than without, and are explored for various pole-lengths. View full abstract»

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  • Axisymmetric formulation for boundary integral equation methods in scalar potential problems

    Publication Year: 1983 , Page(s): 2364 - 2366
    Cited by:  Papers (4)
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    Axisymmetric geometries often appear in electromagnetic device studies. The authors present an original formulation for Boundary Integral Equation methods in scalar potential problems. This technique requires only 2D boundary in the r-z plane and evaluation of the equations only on those boundaries. View full abstract»

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  • The multiple multipole method in electro- and magnetostatic problems

    Publication Year: 1983 , Page(s): 2367 - 2370
    Cited by:  Papers (11)
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    We describe a semi-analytical method which may be applied to solve problems where either the Laplace or the Helmholtz equations are involved. The core of the MMP method is a general and very flexible multipole expansion of regular solutions of the Laplace or Helmholtz equations which allows the use of simple and inexpensive numerical techniques even in cases with complicated boundaries. After the theoretical description of the MMP method we will report about our experience using this method implemented in a computer program for the calculation of two-dimensional electro- and magnetostatic problems. View full abstract»

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  • Automatic computation of optimum origins of the poles in the multiple multipole method (MMP-Method)

    Publication Year: 1983 , Page(s): 2371 - 2374
    Cited by:  Papers (4)
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    This paper gives a strategy to calculate the optimum origins of the poles in the multiple multipole method, which contains as a special case the charge method (method of images). The field, given finally as a linear combination of basis functions fiis built up one function after another. For each basis function one has to solve a nonlinear problem in two or three independent variables. View full abstract»

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  • The contribution of the finite-element method to the design of electrical machines: An industrial viewpoint

    Publication Year: 1983 , Page(s): 2375 - 2380
    Cited by:  Papers (9)
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    The priorities in an industrial organisation differ somewhat from those in academic institutions. This paper describes finite-element electromagnetic and electric field programs developed by an industrial research laboratory for use by engineering departments, and outlines experience obtained. Typical applications 2-dimensional, quasi-3-dimensional, and 3-dimensional programs, including somewith iron non-linearity and eddy currents, are described. Data generation, post-processing and the economics of computation are discussed. The paper concludes with a brief look at future developments. View full abstract»

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Aims & Scope

IEEE Transactions on Magnetics publishes research in science and technology related to the basic physics and engineering of magnetism, magnetic materials, applied magnetics, magnetic devices, and magnetic data storage.

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Editor-in-Chief
Pavel Kabos
National Institute of Standards and Technology