From the viewpoint of high performance of electrical devises, four types of high Si steel sheets have been developed. A 6.5%Si steel sheet shows low iron loss and low magnetostriction so it contributes to high efficiency and low noise in electrical equipment. A Si gradient electrical steel sheet which has gradient distribution of Si throughout sheet thickness with higher concentration of Si at the surface layer of the steel sheet. The Si gradient steel shows low iron loss in high frequency range, so it suitable for high frequency motors. A Si localized steel sheet shows even lower iron loss than Si gradient steel sheet, so it is used in high frequency reactors. A high magnetic flux density Si gradient steel sheet has high permeability and high saturation magnetization, so it is suitable for high torque motors.

　This paper reviews the historical background of grain-oriented electrical steel, ORENTCORE HI-B, and the relevant technology. This magnetic material contributes mainly to large power transformers, and its development is supported by the magnetic domain theory, the observation, and the application techniques to the electrical devices.

　This contribution introduces a fabrication method of Fe-Ni-system bilayer ribbons with positive and negative magnetostriction constants and improvement of soft magnetic properties using the magnetoelastic effect for high-frequency driving magnetic applications. We used an electroplating method to prepare a Fe₆Ni₉₄/Fe₅₆Ni₄₄ bilayer ribbon and measured the magnetic properties of a toroidal core with the ribbon. The shape of the hysteresis loop changed depending on the inner layer (inner magnetic phase), indicating that the induced anisotropy’s direction by the magnetoelastic effect changed depending on the inner layer. The increase in the coercivity over frequency was suppressed when the Fe₅₆Ni₄₄ layer was on the inner side, suggesting that controlling the anisotropy’s directions reduces eddy current losses. We conclude that a bilayer ribbon with different signs of magnetostriction constants is attractive for reducing coercivity (iron losses) under high frequency driving.

　Iron dust cores manufactured by powder metallurgy and pressure forming insulated iron particles have a high degree of freedom in shape, making them suitable for small motor cores, reactor cores, inductors, etc. However, the magnetic properties of the iron dust core are not as good as those of conventional laminated cores because an insulating materials and silicone resin are used between the iron particles to reduce eddy current loss. The author succeeded in shaping powdered iron cores without using silicone resin. This time, the results of varying the pressure force required when shaping powder iron loss without using a binder from 30kN to 200kN are represented. By increasing the shaping force, the magnetic permeability and density significantly increased, and although the eddy current loss did not change, the hysteresis loss significantly decreased.

　In recent years, accurate magnetic properties of electrical steel sheet have been needed to develop high efficiency electromagnetic devices. IEC standard, Epstein frame and the single sheet tester is often used for magnetic property measurement, especially for commercial transactions. But they are not proper to material evaluation, because of their poor accuracy. Therefore, we have developed a unique single sheet tester that features H coil method and stress load option for magnetic analysis and design of high efficiency electromagnetic devices. In this paper, we disclose an overview of our practical single sheet tester (S-SST), and introduce recently standardized single sheet testers for amorphous strip and magnetostriction properties.

　A multiple-degree-of-freedom (multi-DOF) motor can constitute small-sized and high-speed systems capable of performing complicated motions. Furthermore, the prospects for applications to industrial instruments via a direct drive are promising. This study aimed to develop a medium-sized rotary-linear motor of a few kW power or more with rotational and translational motion capacity. Here we present a method for increasing the output of a rotary-linear base on salient pole field, which can enable the use of soft magnetic materials with low eddy-current loss as iron cores. First, a method is presented for magnetize the salient poles using the d-axis armature current. Next, we confirm the torque and thrust characteristics using the proposed method. We find that the proposed method has a higher output than the reluctance torque.