Efficient and Cost-Effective ZCS Direct AC–AC Resonant Converter for Induction Heating

Domestic induction-heating technology requires specific features such as high output power levels in a reduced enclosure, elevated operating temperature, large load variation, and reduced cost. To fulfill these requirements, classical solutions are based on the combination of a rectifier and a dc-link inverter. This is a well-balanced solution, but there is still room for efficiency and cost improvements. Unlike previous proposals, this paper proposes a direct ac-ac converter to reduce the component count, reduce cost, improve reliability, and increase efficiency. The proposed converter is a voltage-source series-resonant converter that achieves linear output power control, reducing control complexity. Moreover, the proposed converter achieves soft switching during both turn-on and turn-off transitions, further improving the efficiency and enabling the selection of low-speed devices with improved conduction properties. A 3.6-kW converter has been designed and implemented, verifying the feasibility of the proposal and the expected performance.