The DC voltage of the VSC is very high and it is necessary to connect several IGBT in series. Some snubber circuits have to be used to restrain the over-voltage of IGBTs so as to avoid its damage and the snubber circuit will increase the current stress too. The over-voltage of IGBT in the converters is studied in the paper firstly. Then, the common snubber circuits used in series-connected IGBTs are discussed and compared. A simulated model is set up in Saber to study the snubber circuit at last, the results show that the RC snubber circuit is more suitable for series-connected IGBTs.
