Design and Parameter Estimation of Series Resonant Induction Heating Systems Using Self-Oscillating Tuning Loop

This paper presents a design procedure and a new control method for power regulation of series resonant Induction Heating (IH) systems using a self-oscillating tuning loop. The proposed power regulator can accurately estimate the instantaneous phase angle and the main parameters of the resonant load. Moreover, the power control algorithm is devised based on a combination of Phase Shift (PS) and Pulse Density Modulation (PDM) methods. For simplicity, the tuning loop utilizes the PS control method for power regulation. Moreover, the Pulse Density Modulation (PDM) and frequency-sweep methods can be used in the proposed tuning loop. The new method is verified by a laboratory prototype with an output power of about 220 W and an operating frequency of about 60 kHz.