Electromagnetic Systems with Iron-Free Inductors for Induction Heating of Moving Strip in Transverse Magnetic Field

The chapter discusses electromagnetic systems for thermal treatment of metal strips using the induction heating by eddy currents. A mathematical model of the heating device is used for analysis, which includes an inductor to generate an alternating magnetic field and the metal strip moving in this field. Flat-shaped inductors without magnetic cores are considered. To solve the three-dimensional electromagnetic field problem considering the movement of the conducting medium, an analytical method based on representing the current load as a two-dimensional harmonic series expansion is applied. To solve the problem, an analytical method and mathematical models are used to investigate the electromagnetic interaction between field sources and the conducting body. The temperature distribution in the strip is obtained by solving heat transfer equations with internal heat sources. Specific temperature calculations are performed using numerical methods. The analysis begins with the general problem of heating systems using inductors in the form of flat contours of arbitrary shape. Then, the results for specific contour shapes of canonical forms such as rectangles, rhombuses, and ellipses are presented. For these systems, the distribution of the electromagnetic field, current density, and temperature in the strip has been determined. The equivalent resistance, efficiency coefficient, and power factor of the devices have been calculated. The influence of the winding height of the inductor on these parameters has been analyzed. It has been found that the considered flat geometrical inductors do not provide uniform heating of finite-width strips. To achieve uniform heating across the width of the strips, combinations of current contours are proposed, where the geometric dimensions are determined by the size and electro-physical parameters of the metallic strips.