Synchronization on the points of turn-off time of series-connected power semiconductor devices using Miller effect

In order to improve the reliability and efficiency of high-voltage power converters using series-connected power transistors, a novel method for series connection of power transistors has been proposed, simulated, and studied experimentally. This method has the following advantage compared with conventional methods: the snubber losses and switching times can be reduced by minimizing the value of snubber capacitors: the number of connected devices is not limited; the method is unrelated to the sequence of turn-off; and the circuit is relatively simple. This novel switching algorithm for series connection is able to implement not only dynamic voltage balancing despite the difference of switching characteristics but also the minimization of the value of the snubber capacitor by the Miller effect