Considerations on the analysis of an induction heating system

This paper presents some considerations on the analysis of an induction heating system and problems that arise during the heating process of steel pieces. The steel pieces under the heating process are modeled to be used as electrical circuit elements of the heating system load. The model of the steel pieces under the heating process consists of a resistive — inductive circuit in order to underline the resistive and inductive effect of the load that influences the thermal process. Using this approach, the whole system is presented as a power electronic one in order to assure a generalized model that can be used further to develop control strategies or to optimize the heating process. A class D series resonant inverter was chosen to assure a high efficiency of the electrical energy conversion. The inverter is accomplished with power MOSFETs that allow high operation frequency of the heating installation. Using the high frequency operation, tens of kilohertz, the system offers the possibility to make even a surface heating of the steel pieces. To model the induction heating system, two simulation software were used: FLUX 2D and MATLAB. First simulation software was used to describe in time the electro thermal behavior of the load and the second simulation program was used to model the induction heating system seen as a whole. This analysis is useful in the designing of induction heating installations and the evaluation of their operation.