Hello Eric,

Thank you for your model, sym and example circuit.
I have copied model and sym files and now can open the circuit

When I run it as it is without any modifications, after 10ms the simulation goes free slowly.
Please tell me what points shall I check further.

Thank you

hi denison,
This is the MOC3081 [ZC Triac]
If you need more info just ask.
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Added: asy model

 

I just want to say that there are several sources online where you can find LTspice models for the MOC3063 and MOC3043 optocouplers. One popular resource is the LTspice Yahoo Group, which has a library of user-contributed LTspice models, including models for various optocouplers. Additionally, you may be able to find models on the manufacturer's website or on electronics forums.

When searching for an LTspice model, it's important to verify that the model accurately represents the behavior of the component in question. It may be necessary to modify or create a model to ensure that it accurately reflects the electrical characteristics of the real device.

 

Hi I99,
Please post your LTSpice asc file for the circuit, I can check the running time.
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... One popular resource is the LTspice Yahoo Group, which has a library of user-contributed LTspice models, including models for various optocouplers. ...

There are no longer any Yahoo groups. All of them were eliminated some time ago. The LTspice group can now be found at groups.io.

https://groups.io/g/LTspice/topics
https://www.searchenginejournal.com... of,the ability to use Groups in October 2019.

 

Hi Eric,
Please see attached asc file for the circuit.

Hi I99,
Please post your LTSpice asc file for the circuit, I can check the running time.
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hi @lhagva99
This is what I see on LTS, works OK at a fast run time..
Run the sim using Alternate mode, not Normal
Try this asc file, let us know what you see.
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hi @lhagva99
This is what I see on LTS, works OK at a fast run time..
Run the sim using Alternate mode, not Normal
Try this asc file, let us know what you see.
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View attachment 287598

Hello @ericgibbs
Yes it works fine in Alternate mode.
Thank you.
I have another back to back circuit. But load R2 current is very low. Please help me why current is low. Also gate2 voltage is very low.

 

hi Ih99,
There seems to be a problem with your asc file, all I see is this.
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Update: redownloaded your as file, now I can see it

 

hi Ih99,
Running your asc file.
Could you explain exactly how the circuit is supposed to work.?
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I expect more current through R2 load.
I would like to control 2kW carbon heater with this circuit.
I choose this circuit because single opto triac controls both gates of two SCR.

 

Hello,

I have created two SCR back to back circuit. It uses only one opto triac to drive two gates of SCR.
This circuit will be used to control power of 2kW carbon heater.
But I have issue with simulation which is load R2 current is very low.

I attach here asc file and models library.
Please recommend me what could be an issue with this circuit.

 

hi @lhagva99
Try this asc file.
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BTW: LTSpice requires Vpeak for the V1 source, 220Vac *1.414 =311Vpk

 

Hi @ericgibbs

Thank you very much for your circuit.
I tried but still slow around 10ms, even I use Alternate mode.
I spent some time but I could not find issue with my simulation.
Yes, modified V1 source to 311Vpk.
I attach my circuit file, it might be my simulation config is wrong.
What do you recommend.

Lhagva

 

I tried but still slow around 10ms, even I use Alternate mode.

hi @lhagva99
Do you mean 10mSec run time, if yes that is fast.
Or do you mean the Delay of 10mSec for the first Drive pulse.?
The first pulse delay is set in the V1 parameters.

E
On your Control panel, you have
Max Threads =8
Volttol = 1e-06
Trtol=1
Try my settings
What is your PC main clock rate.?

 

hi @ericgibbs

I meant the simulation becomes slow at 10ms, because my Opto triac LED driving V2 Pulse source Tdelay is at 10ms.
If I change Tdelay to 1ms then the circuit worked. (It seems it is depending on Tdelay)
However load R2 current is still low, even I change settings to as yours. (Max threads = 4, Trtol = 20, Volttol = 1e-06)

My PC speed is as below.
Intel(R) Core(TM) i7-8650U CPU @ 1.90GHz 2.11 GHz
64-bit operating system, x64-based processor

Thank you
Lhagva

 

Hi @lhagva99
Pleased to hear you have it working.

May I ask why you are firing the SCR gate at Min/Max of the Mains sine wave, usually the SCR Gate is switched at the Zero crossing of the Mains signal.?
This minimizes the radiated switching noise.

I will see if I can find the reason for low current through R2.
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BTW: My PC is 32Bit a 4GigaHz, running Win 10

 

Hi @lhagva99
This is a strip version of your circuit, it appears the SCR model has a problem?

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Edited: changed the SCR type for1st image.

 

hi,
Your circuit with different SCR model
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hi @ericgibbs

Thank you.
I try to fire SCR gate when zero crossing.
But as you can see from below waveforms, it seems that current through load R2 is phase shifted.

Hi @lhagva99
Pleased to hear you have it working.

May I ask why you are firing the SCR gate at Min/Max of the Mains sine wave, usually the SCR Gate is switched at the Zero crossing of the Mains signal.?
This minimizes the radiated switching noise.

I will see if I can find the reason for low current through R2.
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BTW: My PC is 32Bit a 4GigaHz, running Win 10

 

hi,
Your circuit with different SCR model
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View attachment 287662

Thank you.
Now it works perfectly, with S4025L.
SCR Gate is switched at the Zero crossing of the Mains signal, as expected.

I have downloaded BTW69 model from ST website, it seems this model has issue.

Thank you again.