Improved induction-heating inverter with power factor correction

Abstract

An inverter aimed at induction heating applications is presented. It features power factor correction and fast response to sudden changes in the load, while providing the capability to vary the power supplied to the load. Power variation is achieved by means of pulse density modulation using variable-length sequences; thus allowing a high number of power levels to be achieved. The minimum quality factor necessary to make the harmonic spectrum independent of the modulation is also specified; this ensures that most of the power transferred to the load will be at the resonant frequency.