We have focused on stress magnetic anisotropy in various magnetic anisotropy of motor core materials. We have been developed a system for measuring the magnetic property vector under the various magnetic flux and stress conditions in order to clarify the between the stress and magnetic property. In this paper, we will measure the vector magnetic properties of a non-oriented electrical steel sheet under alternating and rotating magnetic flux conditions by applying the uniaxial and biaxial tensile stress. It was clear that the stress magnetic anisotropy changes by applying the uniaxial and biaxial tensile stress. In addition, a method for controlling the magnetic properties of the core material is presented with a high-frequency induction heating.

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High-speed motors are effective for achieving high power in small motors, but the increase in core loss due to highfrequency excitation is a problem. The most effective way to reduce core loss in a motor is to use a magnetic material with a thin thickness. However, to further reduce core loss, it is necessary to optimize the iron core shape by numerical analysis considering the detailed magnetic properties of the magnetic material to be used in a motor. Vector magnetic property analysis can obtain detailed core loss distribution in a motor and is useful as a tool to support the motor core shape design for core loss reduction. This paper presents investigation examples of core loss reduction in motor stator iron core using the vector magnetic property analysis which the authors have carried out.

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In this paper, the “Secondary Current Heating method,” which has been proposed in the previous reports, was used to heat-treat the laminated stator cores of actual motors to reduce iron loss. To evaluate the magnetic properties of the laminated stator cores including the teeth, an inner core was installed inside the stator to form a closed magnetic path with the two teeth, back yoke, and inner core. The air gap between the stator and the inner core causes the loops to be tilted compared to the B-H loop of the back yoke, though, it was found that the iron losses were reduced by about 30% in the laminated stator core after heat treatment.

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In recent years, in response to carbon neutrality, a variety of motor designs and motor developments have been progressing for various applications. This paper presents an example of the application of low-loss magnetic materials to motors and their effects. Although the motor is a mature product, we were able to confirm that it is still possible to improve output density and reduce loss through improvements in soft magnetic materials.

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In this study, a new tool having an electric field as well as a magnetic field to the micro-processing on the inner surface of a cylinder using magnetic compound fluid (MCF) was developed, and its fixed-point processing characteristics were investigated. The tool consists of ring spacer stacked between ring permanent magnets. An electric field was applied between the rims of the two ring permanent magnets. It was elucidated that the tool has the feasibility of the stable application of the electric field during a long period. It was also clarified that there is the correlation between the torque acting on the tool and the amount of material removal per both processing area and distance at the application of the electric field.

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It is predicted that the demand for electric equipment that can achieve high efficiency and energy savings will continue to increase However, there are concerns about resource depletion of materials for high-performance magnets, which are essential for highly efficient electric equipment. We considered reducing the amount of rare metals by increasing the coercive force through grain boundary diffusion of heavy rare earth materials and by separating the magnets of linear motors. The results showed the possibility of significantly reducing the usage of rare materials such as Dy and Tb. Furthermore,in order to evaluate the basic performance of the electromagnetic suspension, a prototype linear motor using divided permanent magnets was fabricated and its thrust characteristics were evaluated. As a result, it was confirmed that the expected thrust characteristics could be obtained.

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