Voltage balancing optimization of series-connected IGBTs in solid-state breaker by using driving signal adjustment technique

Abstract

Hybrid or solid-state DC breakers offers new possibilities for development of a large scale high voltage direct current (HVDC) grid by simplifying the DC breaking process. Generally, series-connected insulate gate bipolar transistors (IGBTs) were implemented in solid-state DC breaker to withstand the turn-off transient overvoltage across it. However, the IGBTs are expensive power semiconductor devices that are highly sensitive to transient overvoltage, thus their voltage balancing during the turn-off transition need to be carefully concerned. This paper investigates the voltage unbalancing factors of the series-connected IGBTs in a solid-state DC breakers first. Aiming at synchronizing the voltage overshoot amplitude of the series-connected IGBTs during the circuit breaking, an active gate drive circuit and its corresponding voltage balancing technique are proposed. It is shown in small-scale experiment that if the voltage overshoot deviation between series-connected IGBTs are effectively minimized.