The thyristor is usually turned on with by applying a gate signal. In labs, I find that a separate driver circuit is used to provide the gate pulse. But since a controlled gate pulse is what is required, can't a pulse generator (which is already available in the labs) provide this? Why is a sophisticated driver circuit (which is made just for the purpose of turning on thyristors) used to turn on a thyristor?

 

Because you need to control the impulse and a simple pulse generator will burn the load or the thyristor. A current defence is needed, plus you need to supply the proper voltage on the "gate". The voltage on the output is " gate-0.6v".

 

In what kind of circuit is the thyristor used? If it is a phase controlled power regulator (light dimmer etc) then the gate pulses need to be synchronised with the AC supply which would be difficult with a pulse generator.

 

In what kind of circuit is the thyristor used? If it is a phase controlled power regulator (light dimmer etc) then the gate pulses need to be synchronised with the AC supply which would be difficult with a pulse generator.

The supply source is DC (as in an inverter - converting DC to AC)

 

The supply source is DC (as in an inverter - converting DC to AC)

In that case, when the current rises too much on the load, the driver stops the thyristor. Plus it might be an impulse driver to prevent the thyristor from overheating by switching it "on" and "off" at a high frequency. That way you also prevent the load from burning, you can measure the current on the load and before it rises, you can stop the thyristor for a small time and then start it again.

EDIT:
For making a driver you will need an "RC" circuit or something after the thyristor to turn the signal into an AC one. If you supply different voltages on the thyristor "gate", like 0v, 0.1v, 0.2v, etc., until you reach the peak of the AC signal you want, than you can create such a driver. It can be done with a bipolar transistor also, but you will still need the driver.

It can also control the voltage on the thyristor, if it was an AC signal, you can stop before you reach the peak of the AC signal and that way you change the shape of the output AC signal.