Electronics > Projects, Designs, and Technical Stuff

Homemade IGBT MIG welder with ATX PSU parts. [blown yet again][blown count: 5]

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MagicSmoker:

--- Quote from: strawberry on June 22, 2019, 11:58:19 am ---for $500 worth of parts you could start to compete with miller

--- End quote ---

Not when you are buying those parts in quantities of 1-10 from the usual distributors. Also, $500 worth of parts does not get you a Miller design... And I know at least anecdotally of what I speak, as I have a cute little Miller inverter TIG/stick welder that is almost 20 years old (!) and still working great. It is a real work of art inside and uses a phase-shifted full bridge topology; something that was still very much considered "experimental" at the time.

EDIT - apparently Miller didn't design this model (MaxStar 140 STR), either... so not even buying a Miller will get you a Miller design... Oy vey!



--- Quote from: Refrigerator on June 22, 2019, 12:17:28 pm ---The flyback core was my initial idea, i've seen people use four smaller cores to make one larger core, but what i decided to use isn't that.
As mentioned it was from the back of a CRT, and as far as i'm aware there are no TV's where the flyback transformer is mounted to the C
...
Edit: finally remembered, the coil is called a degaussing coil.

--- End quote ---

Oh dear...  :-BROKE

Refrigerator:

--- Quote from: MagicSmoker on June 22, 2019, 01:55:14 pm ---
Oh dear...  :-BROKE

--- End quote ---
It will work, i promise  :-DD

strawberry:
my asumtion is based on my calculations for 230V 3 phase inverter. 300$ is enough to make decent welding inverter

interesting question is, how are you going to make wire feed mechanism?

cur8xgo:
I think its possible to cobble together a working prototype of this in a month if you approach it seriously, have a basic understanding of the design issues (especially switching transients destroying things), and can get the magnetics close enough for a 30 second weld.

Can we organize the design plan a bit?

Topology: Is this a 115VAC rectified to DC switched into xfrmr for 24V out or something like that?
Magnetics (transformer): What is the proposed design? Core and number of turns of what material? How hot will the core and windings get? What is the operating frequency?
Switches: What IGBT? Why IGBT? What temperature will they get to?
Heat sinking: How much power needs to be dissipated and how will it be done?
Switch control: Can't use the existing IGBT control circuit?
Current control: So does this need some kind of current feedback servo loop or not? And how will that be done?
Switching transients: How will these be snubbed?
Full bridge: What diodes and how hot will they get? What sort of capacitance and inductance will be used to smooth the DC for the torch?
Bussing: How will high current be routed as far as bus bars while keeping things very short and balanced?

Its possible to use a completely unregulated voltage source like two car batteries to run a mig welder. But that only applies if the voltage source is near the desired welding voltage. Just something to keep in mind. http://readywelder.com

Siwastaja:

--- Quote from: cur8xgo on June 22, 2019, 03:39:47 pm ---I think its possible to cobble together a working prototype of this in a month if you approach it seriously

--- End quote ---

Yes I agree, but using a degaussing coil as a core material might not be a good start.  :clap:

Nevertheless, do it! It will be fun.

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