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Snubber circuit design -- max voltage (TIG welder)

I am trying to come up with an intelligent process of selecting components for the snubber circuit.

I am getting very paranoid about possibly frying my welding machine with this inverter circuit. I would like to avoid that at all costs.

I have arrived to formulating my goal as: having a circuit such that under no circumstances there would be voltages anywhere within the welder that would exceed voltages that would normally exist _without_ my inverter.

Otherwise, I am afraid, some existing components may be damaged as they were possibly not designed for such higher voltages.

Therefore, the first step would be to try to measure such max voltages. The manual specifies max voltage as 150V. I think that it would be good to try to limit voltages to 150V, that would be most conservative.

That brings up a question, how to select components.

  1. I would select the snubber caps such that the voltage generated during commutation dead time would not exceed 150V (and should ideally be about 100V). It seems that, assuming a 1 uS dead time and 360A welding current (pessimistic assumptions for my 200a welder), 4 uF of capacitance should take care of it. I hope that I can select resistors such that there would be no dead time at all, but I think that I can get to be no more than 1 uS dead time.

  1. I would also add a varistor set to start conducting at (having a breakdown voltage of) 150V. Here I am somewhat confused. Varistors have different ratings, DC, AC, etc. What varistor rating should I choose so that it breaks down at 150V.

If my post makes any sense at all, I would like to hear the answer to my question in point 2. Thanks.

i
Reply to
Ignoramus26745
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I do fault your posts, because usually it's not clear exactly what configuration you are considering. That's because we must attempt to make "schematic" drawings from your incomplete or slightly vague verbal descriptions, which is not satisfactory. I suggest that you learn to make simple ASCII drawings and start illustrating your posts. You can also learn how to simplify your circuit and thereby show only the relevant parts in your post. Then we can give you accurate and useful analysis and advice. And we'll all be happy.

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 Thanks,
    - Win
Reply to
Winfield Hill

Winfield, I will try. I have a web page where I put some materials regarding that inverter project. I will place a drawing there.

i
Reply to
Ignoramus26745

The web page is a good idea, but it's been filled with empty pages, which is worse than useless, because it's a big turnoff. I suggest it's not a good idea to have empty placeholder pages (unless marked *on the link*), because people click on them and after a few, they won't come back. I'm not going back until you tell us there's stuff to see, OK? OK.

--
 Thanks,
    - Win
Reply to
Winfield Hill

Perhaps I should have included "nearly-empty" pages in my comment.

--
 Thanks,
    - Win
Reply to
Winfield Hill

There was one empty page called Components, I removed it for now. I did not yet make a drawing/schematic of where my inverter will be placed in the system.

i
Reply to
Ignoramus12686

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