Optimal Design of Reverse Blocking IGCT for Hybrid Line Commutated Converter

The hybrid line commutated converter 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 article 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 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 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 article not only provides a practical guidance to the design of the RB-IGCT, but also promotes the development of the HVdc transmission system.