About using MOC3021 and BTA12

[stuncer]

Hello

I am trying to set up a circuit to run a 1.5KVA three-phase motor in a standard way. Unfortunately, I am not very knowledgeable about power switching as I have been working on logical cards and mcu software until now.

Although I spent the last few days to find the relevant resistor and capacitor values, I could not reach the result.

I put a lot of effort into the training videos from the application notes I read.
AN-3003 I found a formula for R1 on page 4. But I couldn't understand where he got the 1.2A value in that formula (If it's "Peak Repetitive Surge Current" in MOC3011's datasheet, it says 1A)
Also, there is no R2 in my drawing, according to that example, should the sum of R1+R2 be 180 ohms?

There is also a concept like dv/dt that I still haven't been able to solve clearly.

Some application notes that I'm trying to understand
onsemi . com/pub/collateral/an-3003.pdf
onsemi . com/pub/collateral/an-3008.pdf
st . com/resource/en/application_note/an4993-how-to-implement-a-scr-or-a-triac-in-a-hybride-relay-application-stmicroelectronics.pdf



I would be grateful if anyone can help me determine the values I need ( R1, R2, R3, C1, C2) or provide a source that even someone at my level can understand.

 

[BradtheRad]

or provide a source that even someone at my level can understand.

A conventional triac driver is included in Falstad's animated interactive simulator:

https://tinyurl.com/26a67n8e

By clicking the link above:

1) Navigates to website falstad.com/circuit.
2) Loads the schematic into the simulator.
3) Runs it on your computer.

Move the Phase Control slider to shift turn-on time earlier or later.
The lamp grows brighter or dimmer.

Don't expect a basic triac driver to derive 3-phase power from one AC waveform. It takes more effort and more components.

 

[stuncer]

Move the Phase Control slider to shift turn-on time earlier or later.

Thank you very much for your answer and useful simulator link.

However, I think I phrased my question wrong;

I want to do standard triac control to start and stop a 3 Phase motor directly without changing the phase angle.
I need help calculating the resistor and capacitor values in my drawing.

I would be glad if you can help with this.

Note: I shared only the part for 1 phase in the drawing above.

 

[FvM]

Also, there is no R2 in my drawing, according to that example, should the sum of R1+R2 be 180 ohms?

???What do you mean, there's obviously R2 in your drawing, also in AN-3003. Capacitor buffers energy for peak current, respectively R1 in the formula means just R1.

--- Updated Jul 11, 2023 ---

You need a 600V rated opto triac for 380V.

 

[stuncer]

???What do you mean, there's obviously R2 in your drawing, also in AN-3003. Capacitor buffers energy for peak current, respectively R1 in the formula means just R1.

You are right, it is in my drawing, but there is no R2 in the drawing in AN-3003, whose photo I shared.

There is R2 in the drawing just below Figure-2, but it used 180r instead of the calculated 150r, and the value of R1 seems to have changed when R2 is added. Therefore, I thought that the formula given here ( R1 (min) = Vin(pk)/1.2A = 150 ohms. ) is valid for drawings without R2.

I chose 800V when choosing my Triac, but I didn't notice that the MOC3021 has a 400V limit. Thank you for reminding me.
I decided to use MOC3052 instead of MOC3021.
For the snubber in the MOC3052's data sheet, 33r and 0.01uF are suggested for the typical connection for R3 and C2 in the drawing, and 47r and 0.01uF as recommended.

If it does not change according to the load (My load is 1.5KVA asynchronous 3-phase motor), can I use these values?

Since the formula I need to use for the calculation of R1 is "R1 (min) = Vin(pk) / 1.2A", can I use the following formula that I found here for the peak value of Vin?

Vin(pk) = (380/1.732)1.414 = 310.26 V
If I need to use Vin(pk)=310, I guess it will be 310/1.2 = 358r = 390r.
Note: By the way, I still do not understand where the 1.2A value comes from.

If what I've found so far is correct, I still don't know the value of R2 and C1.