On the control system synthesis and its practical evaluation in induction heating systems with resonant voltage inverter

This paper is focused on the power control system of an induction heating system with single-phase resonant voltage source inverter supplied by a three-phase full controlled bridge rectifier. A matching inductor at the inverter output is taken into consideration to maximize the power transfer to the heated piece. In order to regulate the inverter output current, a Proportional-Integrator-Derivative controller is adopted and designed according to the Modulus Optimum criterion in Kessler variant, based on transfer functions. The practical digital signal processor implementation of the control system is performed through an experimental platform based on dSPACE DS1103 control board for rapid prototyping, working together with Matlab/Simulink environment. The experimental setup of the induction heating system is presented and the results of different tests illustrate the proper operation and good performance of the control system. Besides the correct behavior of the current controller, the practical possibility of operating at zero-current switching and of increasing the power by adjusting the control frequency over the resonance value are pointed out.