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This paper proposes an equivalent magnetic hysteresis (B–H) curve for magnetic multiscale problems of complex materials composed of electrical conductors separated by insulating material. The conventional method, which assigns equivalent material constants to each material, cannot properly express the local eddy current loss and the extra magnetic field derived from the local eddy current. To solve this problem, we derive the magnetic hysteresis curve from the volume-averaged magnetic flux density and the surface magnetic field in the micro-model, and apply this curve to the macro-model. The mesh number of the novel macro-model is reduced to around one-tenth that of the micro-model. Magnetic hysteresis is treated by a free energy magnetic hysteresis model, and the macro-model ignores electrical conductivity. The magnetic hysteresis curve and the numerically calculated losses are consistent in the micro- and macro-models. The proposed method well expresses the local eddy current phenomena. [ABSTRACT FROM AUTHOR]

A linear induction motor to be able to achieve induction heating and tension in thin steel sheet treatment process is researched. The major problems in the application of the linear induction motor are meandering of thin steel sheet by the electromagnetic force in the normal direction, the heating characteristic, and the evaluation of the thrust force as a tension. As a result of the investigation of the frequency characteristic by means of electromagnetic FEM calculation, it is confirmed that the electromagnetic force in the normal direction which consists of repelling force caused by the magnetization and repulsive force caused by Lorentz force becomes almost zero at the crossover frequency. In this frequency, the temperature of the steel sheet at the front and back have almost the same distribution. Since the tension value converted from the thrust force is about 10% of experiment equipment, the linear induction motor is also useful for the auxiliary function of the tension roll. © 2009 Wiley Periodicals, Inc. Electr Eng Jpn, 168(2): 38–47, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/eej.20845 [ABSTRACT FROM AUTHOR]

Basic characteristic of electromagnetic force in induction heating application of single-sided linear induction motor (SLIM) which uses electromagnetic AC field is investigated by means of 2-D and 3-D numerical electromagnetic FEM calculation. The electromagnetic force in the normal direction consists of the attractive force caused by magnetization and the repelling force caused by Lorentz force. Although the normal force is canceled by them and becomes zero at crossover frequency, the value is different, which is 2 kHz in 2-D model and is 5 kHz in 3-D one respectively. Since 2-D model expresses only center section of 3-D model and can not express the complex behavior of the eddy current in the whole model, the repelling force caused by Lorentz force is considered to be overestimated when the electromagnetic force value of 2-D model is converted into 3-D one. As a result, the crossover frequency of 3-D model becomes large in comparison with 2-D one. This means that an evaluation by using 3-D model is demanded in order to correctly evaluate the crossover frequency. On the other hand, at low frequency in which the attractive force caused by magnetization becomes dominant, the normal forces of the 2-D and 3-D model are in good agreement. This means that the evaluation by using 2-D model is effective at low frequency. [ABSTRACT FROM AUTHOR]

The authors investigate the effects of double-axis electromagnetic stirring (DAEMS) in continuous casting process, which is composed of a rotational electromagnetic stirrer and a vertical electromagnetic stirrer, using unsteady 3-D hydrodynamic calculation of the molten gallium model. To evaluate the free-surface stability, averaged standard deviation of the free surface is calculated. From the calculation results, it is found that there is an optimum intensity balance between a vertical magnetic stirrer and a rotational magnetic in order to stabilize the free surface. [ABSTRACT FROM AUTHOR]

In the continuous casting process, it is very important to make the dynamic behavior of free surface of molten steel clear, because surface quality of steel is almost decided by conditions of free surface. The conventional MHD calculation, which has been used to design the process, was using only the constant electromagnetic force in the time. Then, we developed new MHD calculation also taking the cyclic electromagnetic force into account, and confirmed that free surface vibrates more intensely than conventional result. Therefore, to make the dynamic behavior of free surface clear, cyclic electromagnetic force must be considered. [ABSTRACT FROM AUTHOR]

A high-response inductive electromagnetic sensor can be made by arranging a conductive and/or magnetic material between the primary coil and the secondary coil. Compared with the conventional inductive electromagnetic sensor, the new sensor has a larger responsivity index (used here to evaluate its characteristics), though it also has a smaller induced voltage at the secondary coil. [ABSTRACT FROM AUTHOR]

Presents a study which proposed an electromagnetic application system to improve the running characteristics at the runout table of the hot strip mill in a steel-making plant by means of electromagnetic force. Running characteristics of thin strips; Electromagnetic force application; Offline experiments.

Presents a study which used a magnetohydrodynamic calculation model to get the optimal operation of in-mold electromagnetic stirring taking into consideration heat transfer, solidification and free surface. Magnetohydrodynamic calculation; Electromagnetic analysis; Fluid dynamic analysis.

Discusses how the magnetohydrodynamic calculation is use to get the optimal operation of in-mold electromagnetic stirring through the fundamental characteristics. System construction of in-mold electromagnetic stirring; Magnetohydrodynamic calculation; Conclusions.

We evaluate the verification of combined system ac and dc electromagnetic field using magneto hydrodynamic calculation. For the effect of level magnetic flow (LMF) that gives the molten steel the breaking force in proportion to the velocity using dc magnetic field, we confirm that the velocity at meniscus becomes stabilized in the time domain and the space domain, though the conventional dual electromagnetic stirring is difficult to realize the stabilization of the meniscus flow dynamics. In the proposed process, it is also confirmed that the velocity at the inner mold is constant in spite of dc magnetic field. [ABSTRACT FROM AUTHOR]

We evaluate an effect of the dual in-mold electromagnetic stirring (M-EMS) which is arranged in series to control the molten steel velocity distribution using magnetohydrodynamic Calculation. A stirring force ratio (SFR) defined as Fu/F1 where Fu is an electromagnetic force of upper M-EMS and F1 is the one of the lower M-EMS is introduced as an index of input. The value of SFR at the optimal condition that meniscus velocity is almost zero, but some velocity is realized at lower M-EMS position. Especially, the SFR condition to have no velocity at free surface is extremely rigorous. This means that it is very difficult to be stable at meniscus by the dual M-EMS system. The lower velocity hardly changes when the SFR changes. [ABSTRACT FROM AUTHOR]

Investigates the phase characteristics of electromagnetic stirring (EMS). System structure; Analytical results; Control of steel quality by EMS; Conclusion.