Shift phase power control in induction heating systems with voltage resonant inverter

This paper is concerned with the design of the power control system for a single-phase voltage source inverter feeding a parallel resonant induction heating load using shift-phase inverter control. The control of the inverter output current, meaning the active component of the current through the induction coil when the control frequency is equal or slightly exceeds the resonant frequency, is achieved by a Proportional-Integral controller tuned in accordance with the Modulus Optimum criterion in Kessler variant. Next are presented different experimental tests performed in order to determine the performances of induction heating system. The objectives of the tests were: the verification of the proper operation of the current through inverter control loop and the verification of the control of the power transmitted to the load by adjusting the inverter frequency.