Optimisation of the reverse conducting IGBT for zero‐voltage switching applications such as induction cookers

The reverse conducting‐IGBT (RC‐IGBT) is a well suited device for soft switching applications, that is, zero voltage switching (ZVS). However, standard RC‐IGBTs are optimised for hard switching, which shows different switching waveforms compared with soft switching. In this study, the optimisation of the RC‐IGBT is described for soft switching applications using the example of an induction cooker. The investigated induction cooker is implemented by using the single‐ended quasi‐resonant topology. Simulations show that main losses of the induction cooker occur in the induction coil and the RC‐IGBT (power switch). The performance of the coil can be improved mainly by minimising the coil resistance. The IGBT‐optimisation is based on the reduction of tail current in the soft switching mode. The IGBT thickness is decreased and the local lifetime is used to achieve lower tail current. A reduction of the overall losses by 30% is achievable. As a result, the cooling system of the IGBT can be smaller and cheaper.