Acceleration of convergence characteristic of the ICCG method

The effectiveness of renumbering for the incomplete Cholesky conjugate gradient (ICCG) solver, which is usually applied to direct solvers, is examined quantitatively by analyzing 3D standard benchmark models. On an acceleration factor which is introduced to obtain convergence quickly, indices for determining the optimum value of the acceleration factor, which minimizes the number of iterations, are discussed. It is found that the renumbering is effective to use with the ICCG solver, and the solver using the acceleration factor gives a good convergence characteristic even in the case when the conventional solver fails to provide convergent solutions</p

Improvement of measuring accuracy of magnetic field strength in single sheet testers by using two H coils

The accuracy of the measured magnetic field strength of single sheet testers using an H coil[1-4] is examined by finite element analysis. An improved measuring method which uses two H coils is proposed from this investigation. It is clarified that the best measuring method of magnetic field strength is the improved two H coil method. The validity of the new method is confirmed by experiments. </p

Investigation of effectiveness of various methods with different unknown variables for 3-D eddy current analysis

Computer codes using the A-&#966;, A-&#966;-&#937;, A*-0&#937;-E, T-&#937;, and E-&#937; methods were developed. The effects of the volume ratio of the conductor region to the whole region, the shape of the conductor, and the ratio of the hole region to the conductor region on the computer storage, the CPU time, and the accuracy of the methods are investigated systematically using a few simple models. The effect of the conductivity of the conductor is also examined. The computer storage, the CPU time, and the error are found to increase with increase of the volume ratio of the conductor region to the whole region. The computer storage and the CPU time are affected by the shape of the conductor in some methods of analysis. The error of the A*-&#937;(E-&#937;) method is larger than that of the other methods</p

Influence of lamination orientation and stacking on magnetic characteristics of grain-oriented silicon steel laminations

Analytical and experimental investigations have been carried out upon the behaviour of flux in laminations, where the rolling directions of adjacent sheets are reversed. The paper clarifies the mechanism of the greatly different magnetic characteristics between such laminations and usual ones, where the rolling directions of adjacent sheets are coincident.</p

New technique for producing a strong multi-pole magnet

A new technique for producing strong multipole magnet is developed. A cylindrical magnet oriented with its easy axis of magnetization perpendicular to the cylinder axis is magnetized by a multipole magnetizer. This procedure results in a multipole magnet with a flux density almost sixty percent greater than the flux density produced by a multi-pole magnet which is not oriented. The technique is especially effective for producing small cylindrical magnets with many poles and agreement of a theoretical analysis with experimental results is very good, with deviations of no more than a few percent.</p

A New Application of Transient Recorder to Magnetic Measurements (Part I: Core Loss Measurement at Very Low Frequencies)

A new method have been developed based upon analogue-to-digital conversion techniques and memories. The method involves the scaling of operating frequency from "real" to "optimum" for the power loss measurement. The advantages of using this techniques are as follows: (1) extreme availability at lower frequency region, (2) high accuracy and high stability, (3) simple measuring procedure, (4) digital indication. This method can be measured the power losses over the frequency range 0.1Hz to 1kHz for magnetic circuit and d.c. to 1kHz in such a purely resistive circuit. We estimate the accuracy of this core loss measuring system within 1.0% over all these frequency range. Using this system, specific core losses of the various grades of silicon iron have been measured in the frequency range 0.1Hz to 200Hz

On the continuity of the magnetizing current density in 3-D magnetic field analysis with edge element

The effects of the continuity of the magnetizing current density on the convergence of the incomplete Cholesky conjugate gradient method and the accuracy of the calculated flux densities are investigated by imposing different continuity conditions for both nodal and edge elements. It is shown that the continuity condition should be imposed precisely in the case of edge elements </p

Direct finite element analysis of flux and current distributions under specified conditions

When the flux distribution of a magnetic circuit is analyzed by using the conventional finite element method, the magnetizing currents must be given. Therefore, if the flux distribution is specified, it is difficult to obtain the distributions of magnetomotive forces or configuration of magnets producing the specified field distribution by the conventional finite element method. New methods which are called the &quot;finite element method taking account of external power source&quot; and the &quot;finite element method with shape modification&quot; have been developed. The processes of calculation in these methods are contrary to the conventional technique. These new methods have the following advantages: (a) If there are many unknown independent magnetizing currents, these currents are directly calculated by the new method. (b) When a flux distribution is specified, the optimum shapes of the magnets can be directly calculated. (c) As these new methods need no repetition, computing time can be considerably reduced. The principles and the finite element formulations of these new methods are described, and a few examples of application of these methods are shown. These new methods make it possible to design the optimum magnetic circuits by using the finite element method.</p

New design method of permanent magnets by using the finite element method

A new method for determining the shapes and sizes of magnets which produce the prescribed flux densities by using the finite element method has been developed. In this paper, the new technique is explained briefly, and then the finite element formulation for non-linear analysis is derived. Finally, the usefulness of the technique is shown by applying this method to the design of magnetic circuits.</p

Application of the finite element method to the design of permanent magnets

A new method of determining the lengths of magnets in a magnetic circuit by using the finite element method has been developed. This method has the advantage that the lengths of magnets which produce the prescribed flux distribution can be directly calculated. In this paper, the error of this method is discussed at first, and then an example of application determining the shape of a magnet is shown. This method is effective for the design of magnetic circuits consisting of several permanent magnets and the determination of the shapes of magnets.</p