I am making a phase controller to adjust speed of an AC motor. I use BT139-600E triac to switch AC voltage and MOC3052M optocoupler without zero-cross to turn triac on. It works fine, even without noise back to AC line, because I added two LC-filters.
Anyway, I see oscillogram is not so good. As I see, it takes about 800µs to turn triac off. That's why it won't turn off at zero-cross, but about at ±80V. Is that because of the snubber RC-circuit?
So the question is: Is there a way to make it turn off faster? Or maybe you can advise other specific triacs for this task? To play with snubber circuit?
I use the usual scheme to control triac with snubber RC and varistor.