Uniform heating control and reduction current unbalance in polyphase induction heaters

To heat metals with high electric conductivity, induction heaters of mains frequency with three-phase inductors are used. To analyze the temperature field condition in the workpiece taking into account non-symmetry of a three-phase current system in the inductor when the power is transferred between the induction heater sections, a three-component mathematical model has been designed. Diagrams of specific surface power distribution along the workpiece length and the workpiece temperature distribution on the surface, on the workpiece support axis and on the end thermocouple installation level in the fixed mode at the end of general heating process are presented. The characteristics of an induction heater available capacity and induction heater resistance-time curves have been obtained. The solution on the power distribution regulation between the inductor windings are posed. The results of the conducted mathematic modeling show that the solutions suggested for three-phase induction heaters enable to increase heating evenness of workpieces of different lengths.