FEA tool based model of partly coupled coils used in domestic induction cookers

This paper proposes a computational model of an inductor system composed of two concentric coils connected each one to a half-bridge inverter. In the first step, the equivalent self-impedance of each coil and the equivalent coupling impedance between coils is obtained from numerical simulations performed by using a commercial FEA tool taking into account the frequency dependence exhibited by the induction heating system due to the presence of induced current in the system. Secondly, the frequency response for each impedance is modeled by means of an electrical network (consisting of three resistances and three inductances) suitable to model induction heating system. Then, the passive equivalent network is used in a computer aided electronic tool in order to perform accurate simulation including the half-bridge inverters and the two-coil inductor model. It is remarkable that the coil coupling implies interleaving between the output signals of the inverters, as a consequence, the control system becomes more complex. Finally, a complete induction system with a concentric double-coil inductor is simulated under different operational conditions. The numerical results are compared with experimental measurements to verify the model.