Two Half-Bridge Resonant Inverters with Coupled Coils for AC/AC Induction Heating Application

In this paper a two half-bridge resonant inverter with vertical aligned coupled coils is proposed for an induction heating application. The system employs two active coupled coils which are modeled using a two-port network approach, being each coil constitutes a series resonant tank fed by a half-bridge inverter. The proposed converter guarantees unity power factor and low harmonic distortion at grid-side current whereas improves power capability in comparison with conventional ones. Power control is reached by: switching frequency, duty cycle and phase-shift displacement between inverters leg. SPICE simulations and experimental results corroborate the converter model and operation. The converter performance is evaluated adopting phase-shift and traditional (switching frequency and duty cycle) control techniques under wide load conditions. The system feasibility is validated using 2 kW prototype with 97% maximum efficiency.