| Abstract |
IGCTs are attractive power semiconductor devices for HVDC applications. However, their switching speed at turn-on can only be controlled by the means of an external snubber circuit, which adds complexity and cost. This paper investigates experimentally the possibility to downsize and even completely remove this turn-on snubber/clamp in the case of an MMC submodule based on 6.5 kV IGCTs, using fast silicon diode modules (rated at up to 13 kA.µs-1). The removal is found to be possible, although limiting phenomena (dynamic avalanche and snap-off) appear, reducing the actual operating range of the submodule. |
