Medium frequency transformer for railway traction: Soft switching converter with high voltage semi-conductors

Nowadays, in railway traction, in order to reduce the weight and the size of the input transformer, several structures using intermediate medium frequency stages are under consideration. The major problem is to reach a high switching frequency with high voltage devices. In this paper, the authors propose a soft commutated topology based on dual structure association. The switching losses are calculated considering 6.5 kV IGBTs in soft commutation mode.