Modeling of Flat Inductor - Workpiece Heating Systems for Design of Induction Heaters

Induction heating systems of geometry similar to Archimedes' spiral are frequently used for heating of flat surface workpieces. Such solutions are characterized by substantial variability of parameters, especially resistance and reactance of wokpiece and inductor. The parameters are function of air gap thickness that determines the electromagnetic field distribution on external surface of heated bodies. Basic task of the article was to show important issues of numerical modeling of such induction heaters, especially connected with proper selection of power sources. The influence of some significant factors on surface distribution of thermal sources was described for a volumetric heating technique. Performed numerical calculations were used to select inductor type and its dimensions to meet a special requirements for heating process. Numerical analysis were extended by circuit calculations of inductor - workpiece system. Basing on field and circuit modeling, a real operating characteristics of heating system powered by voltage and current sources were determined. Results can be very helpful in design process of similar induction heaters.