Optimal Design of Reverse Blocking IGCT for Hybrid Line Commutated Converter

The hybrid line commutated converter (H-LCC) topology has been verified to reduce the commutation failure probability effectively, but the reverse blocking integrated gate commutated thyristor (RB-IGCT) that meets the requirements of this topology has not yet been developed. This study focuses on the optimal design of the RB-IGCT with high blocking voltage, large on-state current, and high turn-off capability. First, an emitter isolation (EI) structure is proposed to tune the low-level injection efficiency, and the forward leakage current can be reduced by 50% without degrading the on-state current. Then, a method for optimizing anode emitter is presented. A high-doped and shallow p+ emitter is preferred to control the current gain while ensuring a low on-state voltage. As to the turn-off capability, the corrugated p-base (CB) structure is used to independently improve the maximum controllable current (MCC). In addition to the corrugation amplitude, the effect of the corrugation width is verified by experiments. Finally, 8 kV RB-IGCT samples are fabricated and tested, which reach over 3 kA average on-state current and 5.5 kA MCC. This study not only provides a practical guidance to the design of the RB-IGCT but also promotes the development of the HVDC transmission system.