The Gate Turn-Off Thyristor in the Cascode Configuration

Application of the cascode technique to the GTO was investigated with the following performance improvements: storage time and current fall time are decreased dramatically and reverse biased second breakdown is; eliminated. This technique permits significant reductions in both turn-on and turn-off snubber losses, the elimination of fuses and a smaller minimum pulse width. Maximum operating frequency is also increased. These benefits come at the cost of a diode in series with each GTO and a slightly larger gate drive circuit. Overall the total drive cost is lower, the efficiency is higher, the control is not as constrained by limitations imposed by the power electronics, and the integrity of the fault protection system is higher.