Electromagnetic Systems of Transverse Magnetic Flux with Ferromagnetic Core for Induction Heating Devices

The research in this chapter is dedicated to issues related to the use of single-phase transverse magnetic field inductors in induction heating devices for thin moving metal strips. The used mathematical models in the research of the three-dimensional electromagnetic field of the induction system allow to apply analytical calculation methods. There are no restrictions on the thickness and width of the metal strip or the frequency of the field. The current load is modeled using conductors in the form of a current layer. The analytical method is based on a two-dimensional integral transformation of the magnetic field and current load. The analytical solution, taking into account the velocity of the conducting medium, is found for the magnetic field in the area of the metal strip and the area without eddy currents. Calculations are made for the current density in the area of the moving strip. In addition to the distribution of the electromagnetic field and current density, specific expressions are obtained for energy and force characteristics. An analysis of the attractive forces of ferromagnetic strips to the magnetic core of the single-phase inductor is conducted. It is established that the electrodynamic stabilization of the strip position in the center of the air gap is achieved in the range of intermediate frequencies (400–800 Hz), depending on the magnitude of the voltage (current) supplied to the inductor. Numerous calculations were performed with using the developed methodology, which allowed to conclude that the minimum heating non-uniformity for single-phase inductors is approximately 15%.