Comparative evaluation of IGCT and GTO thyristor for series connection in high power voltage source inverter based FACTS applications

In this paper, comparative evaluation between 4.5 kV 4 kA GTO thyristor and IGCT for series connection in high power three-level Neutral Point Clamped (NPC) voltage source inverter applications is reported Turn-off tests for GTO and IGCT are compared with RCD snubber at high do voltage and current. Small RC snubber design is optimized and series connection issues for IGCT are addressed Experimental results are compared for a two three-level NPC inverter poles operated as H-bridge with three series connected 4.5k V, 4kA GTO Thyristors and IGCTs per switch.