Analysis of Parallel Operation of 4H-SiC GTOs

SiC GTO is one of the most powerful power devices and very promising in high power applications such as HVDC and MW traction. However, the die size of SiC GTO is limited by the material defects, resulting in small current handling capability of discrete devices. Different from the situation in Si GTOs that parallel operation is never practically feasible, it is potential for paralleled SiC GTOs to balance their static currents naturally owing to the exhibited positive temperature coefficient of on-resistance in their temperature-dependent forward current-voltage characteristics according to our recent study. This paper focuses on analyzing the parallel operation of SiC GTOs. The temperature-dependent forward conduction characteristic and dynamic current sharing characteristics of SiC GTO is firstly investigated. And then the turn-off process is analyzed to explain the reason why turn-off failure occurs. Some possible solutions have also been proposed and verified to solve the turn-off failure problem. Therefore, the feasibility of parallel operation of SiC GTOs is demonstrated, and this will further help improve the power handling capability of SiC GTO based power electronics systems.