Multiphase System for Metal Disc Induction Heating: Modeling and RMS Current Control

This paper presents a multiphase induction system modeling for a metal disc heating and further industrial applications such as hot strip mill. An original architecture, with three concentric inductors supplied by three resonant current inverters, leads to a reduced element system, without any coupling transformers, phase loop, mobile screens, or mobile magnetic cores as it could be found in classical solutions. A simulation model is built, based on simplified equivalent models of electric and thermal phenomena. It takes into account the data extracted from Flux2D finite-element software, concerning the energy transfer between the inductor currents and the piece to be heated. It is implemented in a versatile software PSIM, initially dedicated to power electronics. An optimization procedure calculates the optimal supply currents in the inverters in order to obtain a desired power density profile in the work piece. This paper deals with the simulated and experimental results which are compared in open loop and closed loop. This paper ends with a current control method which sets rms inductor currents in continuous and digital conditions.