High voltage 4 kV emitter switched thyristors

Abstract

In this paper, the characteristics of high voltage (3.5-4 kV) Emitter Switched Thyristors (ESTs) are discussed for the first time. Currently, the GTO is the most commonly used device in the 3.5-4 kV class of power devices. It has a relatively low forward voltage drop (/spl sim/3 V) and high on-state current handling capability. As a bipolar device, the GTO needs a complex base drive circuit due to its low current gain and requires passive protection elements for stable operation. The IGBT is replacing the GTO in the 3.5-4 kV class because it is a voltage controlled device with simple gate control, and good current saturation capability (wide FBSOA). However, the IGBT has a high forward voltage drop (/spl sim/5 V) when designed as a high voltage structure. Devices like the MCT, BRT and the EST have lower on-state voltage drops because of thyristor action. Of these devices, only the EST has current saturation capability. In this paper, we present extensive simulation results on high voltage Dual-Channel ESTs (DC-EST) in comparison to the IGBT. In addition, high voltage DC-ESTs have been successfully fabricated for the first time. These devices were found to have a superior SOA in comparison to IGBTs with comparable forward voltage drops.