An adaptive load-matching method for the induction heating coil with DC power supply

This article proposes a method to transfer maximum power from a power supply to an induction heating load by matching the dynamic resistance of the induction heating resonant circuit with the internal resistance of the power supply source. The method is to select a capacitor connected in parallel to the induction coil and tune the correct value of the inverter frequency to the induction heating circuit resonant frequency. The proposed method can be used for heating work loads with an energy-saving purpose in induction heating applications. The switching frequency of the single-phase full-bridge inverter is variable so that the inverter frequency can be matched with the coil and parallel-connected capacitor (RLC tank circuit) resonant frequencies. To demonstrate the feasibility of the load-matching technique proposed, we experimented with two types of loads that were both stainless steel vessel containers with almost similar size and dimensions but different magnetic properties. We conducted experiments based on the proposed technique and obtained satisfactory results that supported our synopsis. The methods used to collect and analyze the data were carefully chosen and have been described in the methodology section of the research paper. This article proposes to transfer maximum power from a power supply to an induction heating load by matching the dynamic resistance of the induction heating resonant circuit with the internal resistance of the power supply source, as shown in Figure (A). The proposed method includes selecting a capacitor CP, as shown in Figure (B), connected in parallel to the induction coil and tuning the correct value of the inverter frequency to the induction heating circuit resonant frequency. At resonance (Figure C), maximum power is transferred when the dynamic resistance of the resonant circuit is equal to the internal resistance of the DC power supply. image