High Frequency Pulse Density Modulation for cost-effective and efficient multiple induction-heater architectures

Domestic induction heating is a well-consolidated technology that is evolving in order to obtain new products combining three key aspects: performance, efficiency, and cost. New development tendencies suggest the use of multi-inductor architectures to improve the user performance. These systems require the development of new power converters adapted to the new architectures to achieve an efficient and cost-effective solution. The series resonant multi-inverter topology has been proposed as a cost-effective solution for the implementation of multiple output systems. However, the efficiency obtained with classical square wave control strategy is reduced due to the additional series-connected semiconductor devices. In order to overcome this limitation, the High-Frequency Pulse Density Modulation (HF-PDM) is presented. A theoretical analysis of HF-PDM is presented and the output power range and efficiency are obtained by simulation. Finally, these results are verified by means of a multi-inductor lab prototype.