Improving GTO thyristor reliability by use of linear MOSFET amplifiers and controlled avalanching in gate drive circuits

The controlled linear amplifier described has been shown to provide safe and reliable gate turn-off waveforms which may be easily adapted to the circuit conditions. The low impedance coaxial gate connections enhance the performance of the circuit and allow a greater degree of control than is possible using standard wired arrangements. For large GTOs, where the turn-off current may be in excess of 3000 A, both the coaxial connections and a controlled turn-off circuit are desirable for reliable operation. Device reliability and uniform turn-off over the whole silicon area can be ensured by use of gains lower than those typically specified in manufacturers data sheets. With turn-off gains of less than one, true snubberless performance is possible with no risk to the device