| The attention in this paper is directed to the power control in an induction heating system for seamless pipes consisting of a single-phase voltage source inverter with L-LC resonant load supplied by a three-phase full controlled bridge rectifier. The maximal power transfer from the inverter output to the work piece is ensured by the proper design of the matching inductor. The power control is achieved through the inverter output current by making use of a Proportional-Integrator-Derivative controller designed according to the Modulus Optimum criterion in Kessler variant. An experimental platform based on dSPACE DS1103 control board is used for the practical implementation of the control system. It works together with Matlab/Simulink environment and the conceived graphical user interface allows interacting with the experiment. The experimental setup of the induction heating system is presented and the assessment of the control system performance under different tests is performed. Depending on the prescribed value of the inverter output current and the imposed operating frequency, different situations may occur. The possibilities of diminishing the switching losses through zero-current switching and of increasing the power when the operating frequency is over the resonance value are also pointed out. All the results illustrate the proper operation and good performance of the control system. |
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