A transformer-coupled, series-resonant topology for the induction heating of aluminum cookware

Induction heating of aluminum cookware is difficult due to its low resistivity and lack of ferromagnetic properties. Both of these factors result in an effective impedance reflected through the work coil that is too low for practical inverter design and makes efficient coil design difficult. This paper presents a transformer-coupled topology as a means of efficiently delivering the desired amount of power into such low-impedance induction heating loads while keeping the inverter design within practical constraints. This topology consists of a conventional series-load-resonant coil/capacitor circuit. A high-frequency transformer is then used to the couple the series-resonant load to a full-bridge inverter, removing the constraint between load impedance and inverter design. The proposed circuit is built and its operation is experimentally verified.