Thyristors are widely used in converters such as rectifiers and network-supported inverters, however they are not suitable for other applications because they have the disadvantage of not being controllable for OFF state . This is not the case for GTOs. Could someone suggest an easy driving circuit for these type of thyristors?
May be the simplest circuit to on and off the Gate Turn Off Thyrsitor is to apply on its gate a positive pulse whose duration is equal to the on period of the thyristor and then apply a negative pulse between its gate and the cathode. Since the on pulse current is much smaller than the off pulse current, one may use half bridge inverter composed of bipolar power supply two MOS switches one n-channel and one p-channel which are controlled by a suitable clock. The positive branch current for the driving the thyristor on can be controlled by inserting a resistance with a suitable value to it. This also is valid for the off negative current branch.
Best wishes
Thank you very much for your clear and accurate answers. If I understood correctly, a push puller circuit could also be able to drive the GTO !
Dear Bekkara,
welcome again!
Yes, sure, a push pull circuit can drive the GTO.
Best wishes
When turning a GTO thyristor ON, the drive current is multiplied by the current gain in the pn junction at the cathode. However when trying to turn it OFF you have to cancel the entire supply current through the thyristor for at least the turn off time of the device which is why the OFF drive has to be much higher than the ON drive. As my colleagues point out, any low output impedance driver like a push pull circuit should work well. However, bear in mind that many applications of thyristors don't have common ground lines and may be at high AC voltages. Your drive circuit will almost certainly have to work via a transformer.
Interesting ...! Thank you very much professor for the clarifications!
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