M. Enokizono

Rotational power loss of silicon steel sheet

Rotational power losses have been measured on nonoriented grain-oriented silicon steel sheets under different rotational flux conditions. Several methods have been proposed for this purpose. Among these, a method based on the measurement of the field quantities B/sub x/, B/sub y/, H/sub x/, and H/sub y/ seems to be the most convenient as far as the preparation of the test specimen is concerned. In this method, the rotational power loss P/sub r/ is measured as the torque loss generated from the angle of lag between the H-vector and the B-vector caused by the rotating field. The effect of the axis ratio of the rotational flux components and of the inclination angle of field strength relative to the rolling direction of a sample sheet on the rotational power loss was investigated with the method. This loss was compared with the conventional loss, which was shown as the sum of loss P/sub t/ in the x and y directions. Although in the nonoriented steel sheet P/sub t/ (conventional rotational loss) is larger than P/sub r/, in the grain-oriented steel sheet P/sub t/ is smaller than P/sub r/. When the field strength was applied in the nonoriented sheet at a 45 degrees angle from the rolling direction of the sheet, the rotational power loss reached minimum values. >

Effect of ordering on magnetic properties of 6.5-percent silicon-iron alloy

The effect of ordering on the magnetic properties such as magnetostriction, magnetic anisotropy, permeability, and coercive force of 6.5-percent silicon-iron alloy has been studied. The alloys were heat-treated at various temperature, and then quenched into oil. It was found that magnetostriction decreases with the growth of DO 3 structure and magnetic anisotropy decreases with the growth of B 2 structure. By oil-quenching from 500°C, permeability became a maximum and coercive force became a minimum. The effect is caused by the growth of DO 3 structure. The improvement of the magnetic properties of 6.5-percent silicon-iron alloy was attained by controlling the ordering in this alloy through the double heat treatment. The values obtained were maximum permeability μm = 52 000, initial permeability \mu_{i} = 4000 , and coercive force H c = 0.088 Oe measured at the maximum induction of 10 kG.

Recent researches on high silicon-iron alloys

Recent researches on high silicon iron alloys in our laboratory are presented. In the field of 6.5%Si-Fe alloy sheet, the substitution of 1.5% aluminum for silicon improves the cold workability and retains the good magnetic properties of 6.5%Si-Fe sheet. By a splat cooling technique, XSi.YAl.(100-X-Y). Fe ribbons ( 4.0\leqX\leq6.5, 0\leqY\leq2.5 ) in the crystalline state were prepared. They are remarkably flexible and can be easily cold-rolled, and after annealing are mechanically very soft. The good magnetic properties are obtained after annealing at 1200°C for 1hr in vaccum. The magnetic properties of 6.5%Si-Fe ribbon are improved by the double heat treatment. The initial permeability versus frequency curves for 6.5%Si-Fe ribbon are nearly flat up to 100kHz. The ribbon could be used in high frequency magnetic cores.

Magnetic field and loss analysis in an apparatus for the determination of rotational loss

The magnetic field and loss in an apparatus for the determination of magnetic properties of electrical steel under rotational flux conditions using field sensing coils (H-coils) is numerically analyzed by means of finite-element calculations in order to improve the accuracy of the apparatus. The method considered here is based on the determination of the field quantities and makes use of square-shaped samples and an air gap between the pole faces and the sample. The influence of various parameters is studied. The errors in field strength and loss decrease with decreasing gap, but for small gaps it is difficult to obtain circular rotational flux under sinusoidal primary voltage conditions. Furthermore, two different concepts of the determination of rotational loss are considered.

Magnetic properties of 6.5 percent silicon-iron ribbon formed by a melt spinning technique

Silicon-iron alloys containing 6.5 percent silicon can be formed into ribbons by a melt spinning technique. The ribbons obtained were 10-40 μm in thickness, 1-2 mm in width, and 5-10 m in length, and after annealing all of them were remarkably flexible so as to be bent 180°. The as-quenched ribbons are crystalline and are not amorphous. Low loss is maintained for frequencies up to 50 kHz for 15-μm thick 6.5 percent silicon-iron ribbons. The values obtained for as-quenched ribbon were relative permeability \mu_{R} = 6000 , and loss per cycle W_{f}/f= 30 mJ/kg, measured at a maximum induction of 0.8 T and frequency of 50 kHz.

Measurement of Iron Loss Using Rotational Magnetic Loss Measurement Apparatus

Several methods have been proposed for the measurement of the magnetic losses in electrical steel sheet in a rotating magnetic flux. The method considered here is based on determination of the field quantities and makes use of square specimens and an air gap between the pole faces and the specimen. We earlier reported the results of magnetic field analysis on this apparatus by the finite element method. In this paper we report a method for measuring rotational power losses together with measurement results.

Numerical Analysis of Accuracy of Rotational Magnetic Loss Measurement Apparatus

The magnetic field and loss in an apparatus for the determination of magnetic properties of electrical steel under rotational flux conditions using field sensing coils (H coils) is numerically analyzed by finite element calculations in order to improve accuracy. The method considered here is based on determination of field quantities and makes use of square-shaped samples and an airgap between the pole faces and the sample. Errors in field strength and loss are reduced by using optimum yoke construction and the double H-coil method.

Magnetic properties of 6.5% silicon-iron ribbon produced by splat-cooling technique

Abstract It has been found that the silicon-iron ribbons containing up to 6.5% silicon can be prepared by the splat-cooling technique. The obtained ribbons are very pliable in spite of high-silicon—iron alloys. Magnetic properties of this ribbon are discussed.

Simulation analysis of magnetic sensor for nondestructive testing by boundary element method

The use of a differential transformer-type magnetic sensor for nondestructive testing was simulated by boundary element analysis, taking the external electric secondary circuit, the eddy currents, and movements into account. The existence of an error caused by the narrow air gap is identified, an element subdivision method is proposed for decreasing the error, and this method is shown to be effective. The analytical results are shown to be in good agreement with the measurement results. It is shown that the output voltage pattern can be used to estimate the shape or size of a flaw. >

Boundary element analysis for the three-dimensional eddy current problem

The numerical implementation of the boundary-element method formulated for 3-D eddy-current problems is presented. In particular, the algorithm for solving these problems, together with the formulation for the magnetic vector potential and the electric potential using the Lorentz gauge, is discussed in detail. Based on accurate calculations of the numerical solution at interior points in the neighborhood of the boundary, the revised integration method shown earlier by the authors (1988) is extended to this 3-D magnetic field analysis for the steady-state. >