Triac based Dimmer control

[Entity88]

Hi All,

This is my first power electronics project ti start with.

Please find the attached schematics of the same. Unfortunately I am not able to trigger the TRIAC ON, the Load always stays ON with full Voltage across it ( an incandescent bulb), looks like it is conducting through the Snubber ckt R10 & C17.

Please find my attached schematics for your references.

The other point is I am trying to implement Half wave controlled rectifier by triggering the triac only in one of the half cycle…

Please suggest were am doing wrong..

 

[KlausST]

Hi,

You need to provide complete informations:
* what optocouplertriac?
* what exact load (resistance)?
* and so on
* scope pictures, (hand drawn) timing diagrams
* ...

You say you can't turn ON the triac ... but then you say the output us fully ON.
If it's already ON, how will you switch it ON
If it's fully ON, how do you know the triac does not switch ON (since you won't see any difference at the output: ON vs ON)

Unused comparator:
* for unused parts you should give them a "defined state". But shorted inputs ... give no defined output. It will be either high, low, in between or even noisy, oscillating. Shorting the output to GND isn't a good idea at all.
Better set the inverting input a bit higher than the non inverting input...--> defined LOW output state

Klaus

 

[Easy peasy]

what is the power and load connected to J5 ? if not high enough latching and holding current your Triac may not turn on

what is calculated gate current ?

--- Updated Jun 14, 2023 ---

R11 may be too low