Multi phase system for metal disc induction heating: modelling and RMS current control

This paper presents a multi phase induction system modelling 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 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 electronic. An optimization procedure calculates the optimal supply currents in the inverters in order to obtain a desired power density profile in the work piece. The paper deals with The simulated and experimental results are compared in open-loop and closed loop. The paper ends with a current control method which sets RMS inductor currents in continuous and digital conditions

Modelling and control of a multi phase induction system for metal disc heating

This paper presents the study of a multi-phase induction system for metal disc heating. It proposes a complete electrical and thermal modelling of the whole system in PSim software, with a reduced simulation time. An optimisation procedure allows us to calculate the optimal parameters for calibrating the system in order to obtain a uniform heating of the work piece. This was possible from the knowldege of the current density distribution extracted from the finite element software Flux2D® and from the impedance matrix that describes the electrical behaviour of the three coils suuplied by current source inverters. This studies also concern a first simple current control method. As a result, the experimental thermal distributions are in good agreement with simulated ones

Robustness of a resonant controller for a multiphase induction heating system

This paper presents a robustness study of the current control scheme for a multiphase induction heating system. Resonant control has been chosen in order to achieve a perfect currentreference tracking in the inductors with different solutions from the literature. A simplified model of the system is given; it is based on data extracted from finite-element software, including a model of the energy transfer between the dc source and the currents. The metal sheet resistivity will change with temperature, inducingsome modifications in the system parameters. These disturbances will be rejected by the resonant controllers whose pole and zerovariations are investigated. In addition, the tuning method forthe resonant controllers is detailed when the sampling frequency/switching frequency ratio is very low. Some specific stability zones are defined for the resonant controller gains. The application is currently developed on a test bench devoted to disc induction heating

Optimization of the settings of multiphase induction heating system

This paper deals with the setting parameter optimization procedure for a multi-phase induction heating system considering transverse flux heating. This system is able to achieve uniform static heating of different thin/size metal pieces without movable inductor parts, yokes or magnetic screens. The goal is reached by the predetermination of the induced power density distribution using an optimization procedure that leads to the required inductor supplying currents. The purpose of the paper is to describe the optimization program with the different solution obtained and to show that some compromise must be done between the accuracy of the temperature profile and the energy consumption, with the calculation of the losses

Robustness of a resonant controller for a multiphase induction heating system

This paper presents a robustness study of the current control scheme for a multi-phase induction heating system. Resonant control has been chosen in order to achieve a perfect current reference tracking in the inductors while different solutions from the literature. A simplified model of the system is given; it is based on data extracted from finite element software, including a model of the energy transfer between the dc source and the currents. The metal sheet resistivity will change with temperature inducing some modifications in the system parameters. These disturbances will be rejected by the resonant controllers whose pole and zero variations are investigated. In addition, the tuning method for the resonant controllers is detailed when the sampling frequency/switching frequency ratio is very low. Some specific stability zones are defined for the resonant controller gains. The application is currently developed on a test bench devoted to disc induction heating