This paper describes about the core loss (magnetic power loss, iron loss) reduction method for upgrading high efficiency motor. It is difficult to achieve the core loss reduction of motor by using conventional technique. Therefore we proposed the vector magnetic characteristic technology which is constructed magnetic characteristic analytical method, evaluation method of magnetic materials, and the building factor problem. Furthermore as an important magnetic characteristic, magnetostriction phenomena based on new viewpoint are introduced and its numerical simulation results.

The Barkhausen signal was used for the non-destructive evaluation methods in order to evaluate residual stress levels in ferromagnetic materials. However, it cannot be said that this technique has been established completely because the evaluation is usually not done under controlled magnetic flux conditions. When the magnetic field is applied into the materials by the exciting coil, material characteristics will change, therefore, controlling the magnetic flux condition is required for the precise evaluation of magnetic materials. Some results of the residual stress level evaluation using Barkhausen signals under the controlled magnetic flux condition measured from different tensile stressed specimens are shown and discussed them for high efficiency motors in this paper.

The magnetic gear is a device to transmit the motion and/or the torque without contact. Many types of magnetic gears are researched and developed. One is like conventional mechanical gear. This type is researched in long time and some of them become the commercial products. But, a weak point of this type is low usage rate of magnets. So recently the harmonic magnetic gears attract the attention for the high transmission torque and the high usage rate of magnets. This paper reports the recent trend of the researches in the magnetic gears.

Set of basic equations for magnetic fluids are introduced considering internal rotation. Derivation process of the basic equations based on thermodynamics and conservation laws is explained in this paper. Basic equations are obtained from the conservation laws of mass, liner momentum, angular momentum and energy. Basic equations are expressed as dimensionless form and dimensional parameters are defined.

Actuators and sensors using the magnetostriction phenomenon have been studied and put into practical use many heretofore. This paper describes the basis of the magnetostrictive phenomenon, showed the magnetomechanical coupling factor. Then, this paper shows a number of researches that applies magnetostrictive material presented in the Symposium on Electromagnetics and Dynamics, describes the trend of the content of the recent presentations.

Magnetic and Magnetorheological (MR) fluids are formed by small magnetic particles suspended in a fluid such as water or oils. In the absence of an external magnetic field, these suspensions behave as a non-Newtonian fluid. When an external magnetic field is applied to these fluids, magnetic dipole moments are induced in the magnetic particles and many clusters of magnetic particles are formed along the magnetic field direction. Since magnetic and MR fluids are opaque, it is very difficult to analyze the inner structure using common optical methods. Ultrasonic propagation velocity and attenuation in magnetic and MR fluids change with the application of an external magnetic field. It seems that the formation of clustering structures influences on ultrasonic propagation properties. Therefore, the author proposed a qualitative analysis of these structures by measuring properties of ultrasonic propagation. In this review article, we summarized our previous experimental results.