Abstract:
Parallel connection of multiple insulate gate bipolar transistors (IGBTs) is an important approach to improve the current rating of devices in high-power applications of power electronics. And, the key to ensure the safe and stable operation of parallel IGBTs is to realize current sharing for them. Based on the research of the mechanism of existing voltage sharing snubbers of series IGBTs, it is deduced that the variation of IGBT current can be suppressed by series inductors, since the parallel capacitors can decrease the voltage change rate. And then, current sharing snubbers based on series inductors and their improved topologies are constructed by duality principle. The operating principle of novel snubbers is theoretically analyzed by combining with the modal diagrams. It is found that the proposed current sharing snubbers of parallel IGBTs not only possess the advantages of simple structure and easy implementation, but also have the effect of current sharing both in static and dynamic. Simulation and experimental results show that the proposed method can effectively suppress the overcurrent and reduce current imbalance.