A 6-in Integrated Emitter Turn-OFF Thyristor With 17.5 kA Turn-OFF Current

The demand and requirement for high-capacity power electronic devices increase rapidly, and integrated emitter turn-
off
thyristor (IETO) has excellent performance in both
on
-state voltage drop and turn-
off
capability. An advanced 6-in 4.5 kV IETO device is proposed and developed, including optimized package and driver unit. A low-thickness package with compact disc spring assemblies is put forward, which achieved excellent pressure distribution with the same thickness as integrated gate commutated thyristor for complex IETO structure. A composite signal extraction structure without hindrance for ceramic seal is also proposed. Several electromagnetic transient problems during large current turn-
off
are analyzed, such as the emitter voltage oscillation during commutation, the damping characteristics of gate control signals, and the induced voltage on signal extraction structure. Based on the analysis, a new external driver unit with higher reliability for large current is designed. After optimization, a prototype was developed with all problems solved. According to the experiments, the 6-in 4.5 kV IETO achieved 17.5 kA turn-
off
current, and the transient characteristics were verified. The commutation time is less than 300 ns, which has enormous potential for larger turn-
off
current with better gate commutated thyristor (GCT) wafers. Compared with the other GCT-based devices, the IETO in this article reaches the maximum turn-
off
current.