High Power Factor Induction Heating System with Interleaved Variable Duty Cycle

In the past two decades, induction heating has been broadly applied to the catering industry as domestic induction cooker. Currently, due to the numerous benefits brought, such as high heating efficiency, controllability, quiet, and cleanliness, the commercial induction cooker draws increasing attentions in restaurants to replace the traditional stove. The design of a new Ac?Ac resonant converter is applied to the purpose of domestic induction heating and this proposed topology is based on the half-bridge series resonant inverter, using two diodes to rectify the mains voltage. It can be activated with zero-voltage switching during both switches - on and off transitions. This topology and interleaved pulsing achieved a nearly unity power factor. Based on the result, the converter effectiveness and also efficiency are enhanced. The methodical and mock-up results have been demonstrated by means of a 3600-W induction heating prototype. A deep study has been carried out to attain the heating efficiency of induction cooker is more than 96%. The main voltage is rectified and then a medium-frequency current is provided for inverter to feed the inductor. Here the usual operating frequency is taken as more than 20 kHz to avoid the audible range and lower than 100 kHz to reduce switching losses.