GTO Ratings - Gate specification & Specifications related to the switching performance
Gate specification of GTO:
Ig vs Vg:
It is a plot of instantaneous gate current as a function of the gate voltage. This characteristic is valid for DC and low frequency AC gate currents. They do not define the gate voltage when the GTO is turned on from high anode voltage with high di/dt and dig/dt. Vg in this case is much higher. Generally the gate cathode impedance of a GTO is much lower than that of a conventional thyristor.
Igt is the gate trigger current and Vgt , the instantaneous gate cathode voltage when Igt is flowing into the gate. Igt has a strong junction temperature dependence and increases very rapidly with reduced junction temperature. Igt merely specifies the minimum back porch current necessary to turn on the GTO at a low di/dt and maintain it in conduction.
It is the maximum repetitive reverse gate voltage, exceeding which drives the gate cathode junction into avalanche breakdown.
It is the peak repetitive reverse gate current at Vgrm and Tj (max).
It is the maximum negative turn off gate current. The gate unit should be designed to deliver this current under any condition. It is a function of turn off anode current, dig/dt during turn off and the junction temperature.
Specifications related to the switching performance:
td, tr, :
These are turn on delay time and anode voltage fall time respectively. Both of them can be reduced with higher dig/dt and IgM for a given turn on anode voltage, current and di/dt.
ton (min) :
This is the minimum time the GTO requires to establish homogeneous anode current. This time is also necessary for the GTO to be able to turn off its rated anode current.
It is the energy dissipated during each turn on operation. Manufacturers specify them as functions of turn on anode current for different turn on di/dt and anode voltage EON reduces with increased IgM .
It is the maximum anode current that can be repetitively turned off by a negative gate current. It can be increased by increasing the value of the turn off snubber capacitance which limits the dv/dt at turn off. A large negative dig/dt during turn off also helps to increase IFgqm.
The storage time ts is defined as the time between the start of negative gate current and the decrease in anode current. High value of the turn off anode current and junction temperature increases it while a large negative dig/dt during turn off decreases it.
This is the anode current fall time. It cannot be influenced much by gate control.
This is the minimum off time before the GTO may be triggered again by a positive gate current. If the device is re-triggered during this time, localized turn on may destroy it.