T. Nakata

Comparison of various kinds of edge elements for electromagnetic field analysis

A new type of 2nd order edge element is proposed. Various kinds of triangular edge elements for 2-D electromagnetic field analysis are discussed in terms of the definition of vectorial variables, shape functions and accuracy. It is illustrated that the new edge element is more favourable than other 2nd order edge elements from the standpoints of accuracy and selection of variables. The new element can be extended easily to higher order elements and to 3-D elements.

Acceleration technique of waveform control for single sheet tester

An effective acceleration technique using digital feedback to control the flux waveform of a single sheet tester has been developed. In this technique, the waveform of the applied voltage is pre-estimated using the equivalent circuit equation. The convergence characteristic of the proposed method using the new technique is compared experimentally with a conventional method.

Practical analysis of 3-D dynamic nonlinear magnetic field using time-periodic finite element method

A practical 3-D finite element method using edge elements for analyzing stationary nonlinear magnetic fields with eddy currents in electric apparatus, in which the flux interlinking the voltage winding is given, has been proposed. The method is applied to the analysis of magnetic fields in the Epstein frame. >

An improved numerical analysis of flux distributions in anisotropic materials

The method for analyzing flux distributions in transformer cores made of grain-oriented silicon steel is improved in order to reduce error in calculation due to anisotropy in magnetic materials. A model to verify the improved method is proposed, and the calculated results are compared with measured ones. >

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. >

Magnetostriction measurements with a laser Doppler velocimeter

A new method for measuring the magnetostriction of silicon steel sheet using a laser Doppler velocimeter has been developed. This method has the following advantages: (a) non-contact measurement, (b) better resolution (less than 4/spl times/10/sup -8/ m under the condition that the error is within 1%) than conventional methods, (c) measurement of magnetostriction in any direction of anisotropic material and (d) little operator skill required. >

Numerical analysis of flux distributions in cores made of anisotropic materials

Abstract In order to analyze the flux distributions in anisotropic materials, the magnetic characteristics along arbitrary directions, which are quite different from those along the rolling and transverse directions, should be taken into account. This paper reviews the recent progress in measuring magnetic characteristics and computational techniques for evaluating the flux distribution in anisotropic materials.

Three dimensional computation of force in a novel brushless DC linear motor

The flux distribution and static form of a novel brushless DC linear motor were calculated using 3D finite element analysis. An analytical model to increase the force-to-volume ratio of the motor was also validated by numerical analysis. Experimental and numerical results show excellent correlation.

3-D time-periodic finite element analysis of magnetic field in non-oriented materials taking into account hysteresis characteristics

Problems in analyzing 3-D stationary nonlinear magnetic field in non-oriented material taking into account hysteresis characteristics and eddy current, such as finite element formulation and convergence of nonlinear iteration, are discussed.

Effects of geomagnetism and residual magnetism on single sheet testers for amorphous magnetic material

Abstract The effects of geomagnetism and residual magnetism in various types of single sheet testers (SST) on magnetic characteristics, such as the power loss of amorphous magnetic material, have been investigated. It has been clarified that the measured accuracy is affected significantly by the directions of the yoke. The single-yoke types show unfavorable performance when used outside a magnetic shielding room (MSR). If the yoke is not demagnetized, the horizontal double-yoke type requires a MSR. However, the performance of the vertical double-yoke type is acceptable even in the case without a MSR.