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This paper presents measured results of the 2-D vector magnetic characteristics of ultra-thin electrical steel sheets for high-efficiency high-speed motors. Generally, Non-oriented electrical steel sheets with 0.2–0.5 mm of thickness are used for motor cores. However, their thicknesses are not appropriate to use for cores of high-speed motors. We newly developed “Ultra-thin electrical steel sheet” with 0.08 mm of thickness to reduce the core loss of high-speed motors. The magnetic characteristics of the Ultra-thin electrical steel sheets are almost equal to NO (35A300) under exciting frequency of 50 Hz. Since the thickness of the steel sheet is very thin as 0.08 mm, eddy currents are hardly generated under high frequency. As the result, it was confirmed that the iron loss was decreased by 53% when we compare the iron loss of the motor used ultra-thin electrical steel sheets (0.08 mm) to that of the motor used conventional electrical steel sheets (0.35 mm) under the condition of 10 000 rpm.

The magnetic properties of electrical steel sheets, which are used as core materials in numerous electric-powered machines, tend to deteriorate due to residual stress and external loads during manufacturing processes. Previously, we reported our measurement results for the residual stress distribution in a motor core and clarified that sheer stress, along with tensile and compressive stress, exists in the core’s plate and surface, which makes it necessary to evaluate the magnetic properties of the core material under various stress conditions. In this paper, we report the results of an investigation into the effects of an arbitrary shear stress on the vector magnetic properties of a non-oriented electrical steel sheet under both alternating and rotating conditions.

In this paper, we consider the improvement of the stator structure of the self-propelled rotary actuator, whose rotational axis is parallel to the exciting magnetic field. The stator of the actuator is constructed from the grain-oriented electrical steel sheet. The relation between the rolling direction of the steel sheet and the direction of the exciting magnetic field is important for the starting torque and rotational stability of the actuator’s rotor. Therefore, we analyze the rotor in consideration of the rolling direction using the finite-element method that introduced the complex E&S model, which is able to express the 2-D vector magnetic properties. As a result, we estimate the suitable setting direction of the rolling direction in the steel sheet of the actuator’s stator by this analysis.

The viscosity of a magnetorheological fluid (MRF) changes with the magnetic field; however, the behavior of magnetic particles in an MRF under the application of a magnetic field has not been fully clarified. In our previous work, we proposed a real-time observation system in which the torque is simultaneously measured. Textured poles concentrated on a magnetic field, increasing the transfer of torque. In this paper, the behavior of magnetic particles, such as the formation, fracture, and sliding of clusters, in the presence of textured poles as well as the transfer of torque was investigated by in situ observation using our torque measurement system. With increasing depth of the pole texture, the magnetic-field gradient increased, the magnetic field at the edges of the texture increased, the clusters became concentrated in a narrower region, and the maximum torque increased. These results are expected to lead to the design of more efficient torque transfer devices using MRFs.

We have reported the measured results for the magnetic properties of a non-oriented electrical steel sheet under various magnetic flux and stress conditions and proposed a new vector magnetic characteristic analysis technique to consider the stress effect on the motor core. In this paper, the stress effect on the magnetic flux density vector, magnetic field strength vector, and magnetic power loss is examined to improve the performance of electric motors. Thus, the assumed stress distribution is applied to the local part of a stator core, and the vector magnetic characteristic analysis is performed using stress-complex $E$ and $S$ modeling. From these results, the loci of the magnetic field strength vector and the magnetic power loss differed by changing the stress distribution. It was possible to decrease the magnetic power loss by applying a controlled local stress distribution.

In order to reduce acoustic noises and vibrations of electrical machines caused by magnetostriction, it is necessary to make clear the distribution of magnetostriction on magnetic core. The distribution of magnetostriction has been visualized by measured two-dimensional magnetostriction of electrical steel sheet and vector magnetic characteristics analysis technique. The distributions of vector magnetic characteristics and magnetostriction and the relationship between the magnetic flux density vector and two-dimensional magnetostriction have been made clear in the method.

The magnetic properties of electrical steel sheet deteriorates due to residual stress, which occurs during the manufacturing process. Therefore, it is important to know the relationship between the magnetic property and the residual stress in order to utilize electrical steel sheets effectively. This paper presents the effect of residual stress on the magnetic properties of motor cores in a rotating machine. First, the local residual stress distribution of the motor core is measured using an X-ray stress measurement system. Next, the magnetic properties of the motor cores for the different residual stress distributions are measured using a single sheet tester. Based on these results, the maximum permeability and magnetic power loss differed depending on the sample, each of which had a different residual stress. In addition, we attempt to measure the inductance of the motor core in order to easily evaluate the magnetic property. The difference in the inductance of each sample was obtained based on the excitation voltage and frequency measured using an LCR meter. It is very useful to evaluate the inductance in order to easily determinine the difference in the residual stress.

In this paper, the improvement of magnetic properties of oriented electrical steel sheets has been examined by using a laser irradiation system. It is well known that magnetic properties in the rolling direction of oriented electrical steel sheets can be improved by applying laser stress into the surface of the steel sheets. However, the laser stress effect to 2-D vector magnetic properties, which can consider the anisotropy of magnetic properties, has not been revealed. Therefore, vector magnetic properties are evaluated in detail after applying laser stress, and the rotational iron loss can be reduced by laser stress. This paper presents the detailed measured results and discussions on the effect of laser stress to the 2-D vector magnetic properties of oriented electrical steel sheets.

This paper presents iron loss distributions in divided-stator model cores calculated with the finite-element method considering vector magnetic properties. The magnetic anisotropy and rotational iron loss were considered using the dynamic E&S modeling. In this paper, we discuss the differences of the calculated results depending on the direction of the magnetic anisotropy in the divided cores. Moreover, the effect of difference of the junction position of the divided-stator cores on the total iron loss is investigated.

In electrical equipment, such as transformers and motors, rotating magnetic fluxes occur at T-joint parts and back yoke parts. It is therefore necessary to understand the magnetic properties and magnetostrictions under several rotating flux conditions. This paper presents measured vector magnetic properties including 2-D magnetostriction of a nonoriented electrical steel sheet (including a 6.5%SiFe sheet), a grain-oriented electrical steel sheet, and a permendur sheet under rotating flux conditions. The relationship among the magnetic flux density vector, the magnetic field strength vector, and the 2-D magnetostriction is clarified in comparison of the various electrical steel sheets. Furthermore, from the measurement results, suitable materials are suggested for equipment.

Recently, progress of intelligent materials has played a big role in the development of science and technology. We have tried to develop ferromagnetic shape memory alloys to expand application range of the nonmagnetic shape memory alloys, which are typical intelligent material. However, we have not yet obtained a sufficient result, because the magnetic property and the shape memory effect (SME) are in a relation of tradeoff. We have then tried to develop ferromagnetic shape-memory alloys as a composite material using the single-roll melt spinning technique. They are bilayer ribbons consisting of a shape memory layer (Fe-Mn-Cr-Si-B) and a magnetic layer (6.5 wt%Si-Fe-B). The developed bilayer ribbons showed fragile and quite low SME. In this paper, to improve the both shape memory and magnetic properties, effect of Si contents (from 3.5% to 6.5%) of Si-Fe/Fe-Mn-Cr-Si-B bilayer ribbon is investigated.

Magnetic properties of nonoriented electrical steel sheets are influenced by mechanical stress because they exhibit the phenomenon of magnetostriction. Therefore, it is necessary to clarify the relationship between magnetic properties and magnetostriction under mechanical stress. This paper presents the results of measurements of the vector magnetic properties and the magnetostriction of a nonoriented electrical steel sheet under biaxial stress. The loci of the magnetic field strength vector and the 2-D magnetostriction are measured under both biaxial stresses. The magnetic power loss and the peak-to-peak value of the magnetostriction in an arbitrary direction decreased due to the applied biaxial tensile stress. It can be concluded that it is possible to improve the magnetic properties and reduce the magnetostriction of an electrical steel sheet by applying biaxial tensile stress.

To reduce power loss of transformers further from now on and to raise efficiency, we have measured magnetic property distributions in a three-phase tripod V-connection transformer model core. For the measurement, we have developed a localized vector magnetic property measurement system consisting of a three-axis positioning system, a vector magnetic sensor (V-H sensor), and PC. The measured results showed that rotational magnetic fluxes with a large axis ratio were generated in the V-junction parts of the transformer model core, and large iron loss was observed. To reduce the iron loss near the V-junction parts, we have tried to change local magnetic characteristics of the electrical steel sheet near the V-junction parts by using laser irradiation. The effect of the laser irradiation on the local magnetic properties is evaluated by measuring distributions of the local magnetic properties.

Electrical steel sheet that is used as a core in electrical machines deteriorates due to residual stress and external stress. The magnetic properties and stress need to be clarified in order to effectively utilize electrical steel sheet in electrical machines. We have measured the residual stress distribution in a motor core using an X-ray stress measurement device and clarified not only the tensile and compressive stress distributions, but also the shear stress distribution. In this study, a new measurement system is developed for determining vector magnetic properties under shear stress. The vector magnetic properties of the non- oriented electrical steel sheets under the alternating magnetic flux and rotating magnetic flux conditions were measured with the developed system. As the result, it was clear that the magnitude of the magnetic field strength vector and the magnetic power loss along the direction of about 135 ◦ increased by applying the shear stress.

This paper presents a modeling of vector magnetic properties considering residual stress effects in electrical steel sheets. Because the practical phenomenon is too complicated, complex variable expressions are applied to the modeling used in the characteristic analysis with the FEM. We call this stress-complex-E&S modeling. The validity of the developed modeling was verified in comparison with the measurement. The result shows that the developed method is very effective to reduce necessary conditions in the approximate expression of the material coefficients depending on stress.

In this paper, vector magnetic properties measurement and magnetic characteristics analysis of a non-oriented electrical steel sheet under high magnetic flux is presented. At first, the vector magnetic property of the non-oriented electrical steel sheet under the high magnetic flux condition is measured. Next relationships between the magnetic flux density vector $B$ and magnetic field strength vector $H$ of ring core model is simulated by using the database of measured vector magnetic property and a dynamic integration type E&S modeling. As the results, the difference of the maximum magnetic flux density $\vert B\vert_{\max}$ , the maximum magnetic field strength $\vert H\vert_{\max}$ distribution and the local hysteresis loops in the ring core model is obtained by increasing the exciting voltage. In particular, it was clarified that $\vert H\vert_{\max}$ distribution and locus of $H$ vector was effected due to the magnetic anisotropy of the non-oriented electrical steel sheet strongly.

This paper presents the newly proposed heating method named “secondary current heating method” to reduce the iron loss on laminated electrical steel sheet cores for high-efficiency electrical motors. It is well known that the magnetic properties of electrical steel sheets, which are used for electrical motor cores, are deteriorated by the residual stress during manufacturing of the electrical motors, and then the iron loss of the laminated electrical steel sheet cores of the electrical motors increases inevitably. The newly proposed secondary current heating method can improve the magnetic properties on laminated electrical steel sheet cores and reduce the iron loss of them in the very short time in comparison with conventional methods. In this paper, the electromagnetic and heating characteristics of the specimens by the proposed method were confirmed, and then it was applied into the laminated cores to reduce iron loss.

This paper presents measured local vector magnetic properties in a transformer type model core made of a laser-scratched grain-oriented electric steel sheet by using a vector-hysteresis (V-H) sensor. The V-H sensor consists of B-needle probes for measurement of the magnetic flux density vector B and double H-coil for measurement of the field strength vector H. The distance between the B-needle probes was shortened to be 2.5 mm and a 2 mm × 2 mm-sized double H-coil was mounted on the sensor head to realize higher resolution. The measurement accuracy of the B-needle probes was confirmed with a spatial probe, which can change the needle distance from 2 mm to 20 mm. The results show that the detailed local two-dimensional vector magnetic properties depending on laser-scratches are measurable with the developed new sensor.

This paper presents a modeling of vector magnetic properties including effects from residual stress in electrical steel sheets. In simplification we have started development of the modeling from the complex-variable E&S (CES) modeling and additionally considered magneto-elastic effect. We call this stress-complex E&S (SCES) modeling. The developed method was applied to analyze a PM motor model core for verification of the modeling. The iron losses and the building factor can be estimated in the simulation.

This paper presents a frequency sweeping excitation and spectrogram method (FSES method) by magnetic sensor for non-destructive testing of hardened carbon steel. High frequency induction heating can make changes in the microstructure and residual stress. As a result, the magnetic properties such as magnetic permeability, magnetic coercivity and remanent magnetization in materials are changed. This makes it possible to evaluate the hardening conditions by using the FSES method. We tried to examine the degree of yield strength which varies with hardened conditions. Controlling and evaluating of yield strength are very important for actual industrial products.

In the conventional eddy current testing (ECT), it is difficult to estimate wall thinning from outside of pipes without removing the covered materials due to the large lift-off between a pipe surface and a sensor. In order to overcome this difficulty, a long-pulsed excitation system has been developed with a magnetic sensor, by which the magnetic flux can be penetrated deeply inside pipes because of low frequency and small induced eddy current. In this paper, the numerical results and measured results of the newly developed long-pulsed excitation system are shown. The results show the effectiveness of the proposed long-pulsed method for a large lift-off evaluation to wall thinning.

Electrical steel sheet in actual rotating machines is magnetized under alternating and rotating magnetic flux conditions. In addition, the magnetic properties of the electrical steel sheet are affected by mechanical stress strongly and are deteriorated due to the residual stress during the manufacturing process. Therefore, it is important to know the magnetic properties under various stress and magnetic flux conditions. In this paper, we investigated the effect of the mechanical stress on vector magnetic property under alternating magnetic flux conditions. Basing on the results, we can conclude that the vector magnetic property of the electrical steel sheet depends on the mechanical stress and the excitation direction. Therefore, it is important to consider the vector magnetic property with the mechanical stress in the design of the electrical machine.

This paper presents analyzed results of a surface permanent magnet motor by using the complex E&S modeling. The complex E&S modeling is developed to consider the vector magnetic properties simply in optimization procedures with the finite element method although there is a limitation that is restricted by the complex approximation. The conventional E&S modeling is very time-consuming because of strong magnetic nonlinearities and low-convergence property, therefore it is not suitable to use in technical designing. The calculated results with the complex E&S modeling are compared with one of the conventional E&S modeling for verification. The results demonstrate that the complex E&S modeling is very useful in designing under consideration of the rotational magnetic loss and magnetic anisotropy.

Detailed design of machines incorporating permanent magnets requires precise knowledge of materials' magnetization characteristics. Nd-Fe-B magnets are known for their “hard” properties and thorough characterization of these magnets in easy and hard directions requires very strong magnetic fields (in the range of MA/m). Application of such high fields results in high voltages induced in the pick-up coils-in presented case the induced voltage reaches up to 50-60 V. Signal is acquired using precise NI ADC accepting input voltage in range of ± 5 V max. This means that direct connection between pick-up and ADC is not possible. Obvious solution to this problem is to decrease number of turns in pick-up coils, however for high quality results the number of turns should be large and ideally an integer. The ADC could be exchanged but fast, precise and high-input-voltage ADC is not cost-effective. Additionally, especially in case of slow ADCs, transitions present in magnetization signal can exceed available bandwidths distorting the results. Perfect solution to highlighted problems is the attenuation of the signals and their further digital reconstruction. Attenuation might be performed using active integrators-reported error are in the level of 1% in ~3 MA/m field. It might be also based on passive devices-preferred approach eliminating input voltage limits and power considerations for the pick-up system. Reconstruction might be done on the basis of the model of an attenuator or reconstructive filtering (equalization). Two types of attenuators are presented in this paper. RC attenuator which provided reversible spectrum and amplitude adjustment and R attenuator affecting only the amplitude of the signal. Reconstruction error from RC attenuator was on the level of ±0.1% in the most important part of the signal. R attenuator provided comparable error with added merit of very easy de-attenuation procedure which makes it an attractive solution for high field measurements. Some results from Nd-Fe-B magnet characterization in ~11 MA/m (~14 T) field using similar R attenuator device are presented. Proposed passive attenuators made this high field characterization possible.

This paper presents measured 2-D vector magnetic properties of a Fe-Si-B amorphous sheet. The relationship between the magnetic flux density and field strength vector under alternating and rotating flux conditions is clarified by using the 2-D vector magnetic property measurement system. The magnetic anisotropy in plane was observed and it was changed depending on the flux density level. Moreover the iron loss depending on the maximum flux density is shown.

In recent years, high-power electric motors have been mounted on mobile platforms such as electric vehicles. These motors are required to be compact, lightweight, and highly efficient. The reduction of core loss that occurs in electrical steels is an important factor in efficiency. Because core loss is ultimately converted into heat, it can be estimated by measuring the amount of heat generated. Methods for directly measuring the core loss in electrical steel sheets with thermistors and thermocouples have been proposed, but in these methods, many constraints complicate the measurements. In addition, the measurements are not suitable for a large number of sampling points. The aim of this study is to measure the distribution of core loss in electrical steel sheets by using thermography.

Recently, progress of the intelligent materials plays a big role in development of science and technology. We have ever tried to develop ferromagnetic shape-memory alloys to expand the application range of the common nonmagnetic shape-memory alloys, which are typical intelligent material. However the saturation magnetization and the shape-memory effect were in a relation of the trade-off, so we could not get a good result. In this study, we tried to develop ferromagnetic shape-memory alloys as a composite material by using the single-roll melt-spinning technique. They are bilayer ribbons, which have both shape-memory layer and magnetic layer.

This paper presents a non-destructive evaluation study on a radiator with cooling fins as a complex shaped specimen. Radiator structures are used in various heat exchangers, such as automobiles, air conditioners and refrigerators. An eddy current testing method, namely multi-frequency excitation and spectrogram method (MFES), was employed to detect a defect on the radiator tube surrounded by cooling fins. Overall, experimental results suggested that the influence of cooling fin is not as noticeable as that of the defect signals.

This paper deals with a numerical modeling of nonlinear magnetic properties of ferromagnetic shape memory alloys (FSMAs). In order to design new magnetic actuators by using the FSMAs, it is necessary to develop an effective engineering modeling, which can represent the nonlinear magnetic properties depending on stress and temperature. This paper presents measured relationship among stress, temperature and magnetic properties of a Fe-based FSMA. On the basis of the measured result, we have developed a numerical modeling with an arc-tangent function. The modeling is applied to analyze a simple example for verification and the calculated results demonstrate its applicability in numerical simulations.

This paper presents results of iron-loss evaluation of an induction motor model core by using the finite element method considering two-dimensional vector magnetic properties. We propose a new iron-loss calculation method considering higher harmonic components of the flux density waveforms caused by the secondary slot ripples. Influence of the harmonic components on the total iron loss is clarified numerically. In addition, reduction of rotational iron losses is investigated by making holes at the tooth base parts. The results show that the rotational magnetic flux distribution is effectively controlled by making holes. In this paper, obtained knowledge about iron-loss control with holes in the stator core is presented and discussed.

This paper presents results obtained from a numerical simulation of the magnetization distribution of Nd-Fe-B magnets. In the initial magnetization process, we have used the three-dimensional Variable Magnetization and Stoner-Wohlfarth (VMSW) method. In the residual magnetization process and demagnetization process, we have used the magnetization equation of motion. Magnetization equation of motion can be described by the Landau-Lifshitz-Gilbert (LLG) equation. The calculation results were compared with the measured results to verify the accuracy of the numerical simulation.

This paper presents an improved integral-type E&S modeling for applications under high magnetic flux density conditions. In the conventional integral-type dynamic E&S modeling, we assumed linear increment of higher harmonic components including in the magnetic field strength waveforms versus the magnetic flux density. However the higher harmonic components decrease after getting a peak value in rotational magnetization process around saturation region (1.6T – 1.8T). Improvement of the integral-type dynamic E&S modeling for the high magnetic flux conditions was investigated in comparison with the measured one and verification with a simple problem was demonstrated in this paper.

This paper presents measured iron loss properties of a rotating machine's stator core at each manufacturing stage. It is well known that the magnetic properties deteriorate in constructed cores due to stress in manufacturing process and the iron loss increases in comparison with one of the ideal material used in designing, and then the building factor becomes more than one. In this paper, knowledge obtained in development of a simplified evaluation method of iron losses in actual stator co res of rotating machines is presented.

This paper presents results of magnetic characteristic ana lysis of a magnetic flux concentration type surface magnet motor. Firstly influence of number of the rotor poles on the to rque characteristics was examined for fixed stator construc tion and then some constructions of the permanent magnet array were tested to reduce the cogging torque. Their magnetic flux distributions and torque characteristics were calculated by using the finite element method. Permanent magnets with strong magnetism are widely used in daily life. Especially, role of the permanent magnet material used in the motors is very important for our social life, because we can reduce input energy and improve efficiency by using the perma nent magnets. The magnetic energy of the permanent magnets is directly converted into the rotational force, without supplying current to generate the magnetic field of the field system such as the three-phase s ynchronous motors. Miniaturization of the motors utilizing the permanent magnets has being done with progress of the performance of the permanent magnet materials. Recently, technology to generate a strong magnetic filed ove r 4T in a local region by combining the NdFeB permanent magnets has been developed. As a result, it came to be able to obtain larger magnetic energy than that of the magnet pole's surface due to the resid ual magnetization. There is a possibility of a further characteristic improvement of the permanent magnet motors by using the powerful energy produced by combining the NdFeB permanent magnets. However, the applications of strong magnetic field to the permanent magnet motors are limited and a new appl ied technology has not progressed yet. In order to develop a small size and high power motor, higher magnetic flux density in the air gap needs to increase torque and power under a constant revolution speed. Concentration type permanent magnet arrangement is one of the effective solutions to generate high magnetic flux density as mentioned in the above. We have developed a new surface permanent magnet synchronous motor by using the concentrated permanent magnet arrangements. The same magnetic poles of the assembling permanent magnets on the rotor surface are faced to each other to generate larger magnetic flux density in the air gap. We call this the concentrated surface permanent magnet synchronous motor (CSPMSM). In this paper, the torque characteristics depending on magnet arrangements are numerically examined by using the finite element method (FEM).

This paper presents results of magnetic characteristic ana lysis of a three-phase generator utilizing grain-oriented silicon steel sheets. In the analysis, the finite element met hod taking account of the two-dimensional magnetic properties is used to make clear rotational iron loss distributions. In this pa per, the knowledge obtained in the numerical simulations by means of the integration-type dynamic E&S modeling is reported. Also, the measurement results of a prototype generator designed with the magnetic characteristic analysis are shown.

This paper presents magnetic characteristic analysis of an induction motor model core considering two-dimensional vector magnetic properties. In order to reduce rotational i ron losses, which generate in the stator core, we tried to make holes at the tooth base parts. As a result, the rotational flux distrib ution was effectively controlled by making holes. The results showed that reduction of the total iron loss might be possible by find ing out effective holes' size, shape and position.

This paper presents a frequency sweeping excitation and spectrogram(FSES) method to evaluate hardness and hardening depth of carbon steels by using electromagnetic methods. Magnetic properties of carbon steel samples under different hardening temperature condition are examined by using the FSES method. The results show that the magnetic properties of the hardened carbon steels differ depending on the hardening temperature. It can be said that the FSES method is useful to evaluate the hardening depth and the hardness.

To prevent accidents caused by the accumulation of fatigue damage, it is important to evaluate fatigue damage in stainless steel, a widely used structural material. SUS430 (ANSI430) is a ferritic stainless steel. It is well known that the electromagnetic properties of SUS430 such as permeability and resistivity, change due to fatigue damage. The eddy current method can detect change in the electromagnetic properties of SUS430. In this research, the eddy current method using the pancake-type coil was used to find fatigue damage in SUS430. The pancake-type coil was put on a specimen made of SUS430, and excited with alternating current. When a pancake-type coil and a specimen are adjacent, the change in permeability and resistivity of the specimen due to fatigue influences coil constants such as inductance L and phase angle ? of impedance. In our experiment, L and ? clearly depended on an increase in the bending stress and the number of stress cycles. It can, therefore, be said that L and ? are clearly influenced by fatigue damage. In this paper, the results of investigating the relationships between the amount of fatigue damage, bending stress, L, and ? are reported.

The velocities of magnetic domain wall displacements during reversal magnetization in a nano-wire were simulated as a function of impurity and defect densities in the host spin lattice, by using Monte Carlo method. The magnetic domain wall displacement velocity was enhanced for the clusters with defects and it was suppressed for ones with impurities.

In this paper, the vector magnetic property is explained first. And this paper also presents the magnetic characteristic analysis of the electrical machines by using the vector magnetic hysteretic E&S model. Furthermore, the dynamic E&S model, which can analyze the eddy current effect due to the distorted magnetic flux waveform, is presented. From this method, we can express the various kinds of magnetic properties directly, for example, vector hysteresis loops (Bx-Hx, By-Hy) magnetic power loss and the behavior of H and B vectors by using this model.

This paper presents low Curie temperature magnetic materials for induction heating. These materials are alloys based on SUS430. The magnetization decreases with increasing amount of additives. In order to increase the saturation magnetization, while keeping the Curie temperature constant, rare earth materials were added in this study. The compositions of alloys were investigated to realize a suitable Curie temperature. The temperature self-controlling function was also investigated in measurement of temperature distribution by using thermograph apparatus. Furthermore, thermoelectromagnetic field analysis was carried out as a numerical examination.

This paper presents rotational power loss properties of magnetic steel sheets under high flux density conditions using two-dimensional vector magnetic properties measurement. Recently it was reported by some research groups that the magnetic power loss measured in a counter clockwise (CCW) rotating field differed from that in a clockwise (CW) rotating field. This phenomenon was only observed in case of higher magnetic flux density excitation condition. We call this the CCW/CW problem. To clarify the reasons why the disagreement exists in the CCW/CW direction, we have examined angle errors of H - and B -coils by using geometrical, optical and magnetic methods. Then we compensated the measured vector components including different signals due to the angle errors. In the components of irremovable small angle error, we have also used the measured field strength waveforms in CCW/CW conditions. We have applied the compensation method to measurement of a grain-oriented electrical steel sheet.