Help regarding thyristor triggering

[sribalaji]

I need to control the ac power using two back to back thyristors. I've developed the code for the gate pulses and i need to design the triggerig circuit. Could anyone direct me to some useful websites that deals with practical triggering circuit?

I've referred some text books but I am not able to fully comprehend its working. Are UJT and pulse transformer triggering circuits viable? Or a simple RC triggering circuit is enough? I need to provide pulses only for 2 SCR. Any material regarding the working of these circuits would also help.

Thanks for your time.

 

[BradtheRad]

If it's for AC then consider using a triac. It's two scr's combined into one unit. Triggered at one terminal.

Typical trigger method is through a diac. A neon bulb is often specified as a substitute.

It in turn is triggered by an RC network.

Examine a few light dimmer circuits. Very simple methods might use a carefully calculated resistor network to trigger the triac.

https://www.circuitstoday.com/modified-lamp-dimmer-circuit

 

[FvM]

"Code for the gate pulses" suggests a microcontroller interface. Most simple method would be an opto triac, it can work for thyristors as well. Unfortunately you'll lose part of the dV/dt strength that thyristors have in contrast to triacs. A pulse transformer is the more rugged method, it can be driven through a transistor output stage. UJTs are a simple means to generate trigger pulses. You don't need it, if the µC generates the pulses.