| Electronics > Projects, Designs, and Technical Stuff |
| Homemade IGBT MIG welder with ATX PSU parts. [blown yet again][blown count: 5] |
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| DannyTheGhost:
--- Quote from: Refrigerator on June 23, 2019, 10:06:57 am --- Synchronous rectification would over-complicate things. --- End quote --- Sometimes you need to complicate your design when you don't want to dissipate over 50 watts from rectifier |
| MagicSmoker:
--- Quote from: xavier60 on June 22, 2019, 08:55:43 pm ---Interesting, I have been keeping alive a few Castolin/Eutectic PowerMax 2 welders that also have the phase shift topology. Maybe the same as the Miller. --- End quote --- My Miller was supposedly made by Fronius, but Fronius lost the contract with Miller soon after because it couldn't keep up with parts demand. I opened mine up to poke around inside even before the warranty was up and then again about a year ago to check the ESR of the elkos inside and everything was still within spec. Then again, I probably don't put more than about 10 hours of use on it any given year... --- Quote from: xavier60 on June 23, 2019, 01:55:37 am ---I suspect that higher frequency makes the output choke unnecessary. I can't find the choke in the design the I linked earlier. And my old welders don't have a choke. The rectifier output pulses are 100KHz, I think it relies on lead inductance. --- End quote --- The "choke" might be the leakage inductance of the transformer, usually by specifying an unusually large gap for a core that really shouldn't have one in the first place (e.g. - forward mode transformers). Note that this definitely falls in the "ugly hack" category, and not something I would personally try to replicate just to save on the cost/volume of a proper choke. |
| Refrigerator:
The transformer is wound, i took care to make sure the primary is properly isolated from the secondary. Although as much as i tried i could only fit 7.5T in the secondary, no big deal. I couldn't find appropriate litz wire for my primary so i went outside, screwed to screws into a board spaced about 1.7m apart and made some. In the end it was quite a squeeze but i think it looks pretty ok-ish. Now i can begin building the primary switching circuit. |
| Refrigerator:
--- Quote from: DannyTheGhost on June 23, 2019, 10:28:43 am --- --- Quote from: Refrigerator on June 23, 2019, 10:06:57 am --- Synchronous rectification would over-complicate things. --- End quote --- Sometimes you need to complicate your design when you don't want to dissipate over 50 watts from rectifier --- End quote --- A CPU cooler can handle that no problem. |
| cur8xgo:
--- Quote from: Refrigerator on June 23, 2019, 01:10:11 pm ---The transformer is wound, i took care to make sure the primary is properly isolated from the secondary. Although as much as i tried i could only fit 7.5T in the secondary, no big deal. I couldn't find appropriate litz wire for my primary so i went outside, screwed to screws into a board spaced about 1.7m apart and made some. In the end it was quite a squeeze but i think it looks pretty ok-ish. Now i can begin building the primary switching circuit. --- End quote --- very interested to see how that performs? so thats just magnet wire and you twisted it to make litz? how did you decide on litz vs foil? |
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