Enhanced Load Adaptive Modulation of Induction Heating Series Resonant Inverter to Heat Various-Material Vessels

Abstract

Nowadays all-metal induction heating (IH) cooktops have widely been popular to heat various pots fast and safely. A load adaptive modulation (LAM) method has been proposed to improve the performance of the IH power delivery capability and the cost-effectiveness of the all-metal IH system. However, this method shows poor power conversion efficiency at light load conditions because high switching loss is induced by using the pulse frequency modulation (PFM) method in series resonant inverters for IH applications. In this paper, a multi-mode control strategy for the IH system employing the LAM is proposed to improve light-load efficiency compared with the conventional LAM method. The proposed multi-mode control algorithm automatically changes its modulation according to the pots’ material-dependent resistance. The modulation method can be selected to improve the light load efficiency by using the proposed control strategy. Experimental results provide the validity and performance of the proposed multi-mode control algorithm with a 2 kW prototype IH series resonant inverter and various material pots.