Electronics > Projects, Designs, and Technical Stuff

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

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strawberry:
Welder 200A rectifier with two RC snubbers 10n(MKS4 2kV) 2.2R(4x 10R wirewound)
Y2 10n 300V
8x 60A 300V fast diodes TO-247

Refrigerator:
The diodes are finally here, took 11 days from being shipped to arriving at my door (the record so far is 9 days from ordering to arriving at my door)
That aside i'll go put the diodes in and fire the welder up.
Also i noticed that i need to put a freewheeling diode in the welder because i added the inductor.

Refrigerator:
Assembled the welder back together and did a quick test on 12V, the output measures 4V and i get 3.8(-ish) amps when i short it out with my DMM.
So my welder is back and ready to rock and roll, this time i'll have to whip out the variac to test it out.
Before assembling i also measured the diodes by connecting them in a voltage feedback loop in a high voltage boost converter.
This way the output of the boost converter would be whatever the breakdown voltage of the diode is.
All of the diodes came in at around 130V, considering the current flowing through them is much lower than rated at 150V i think these diodes should be allright.

Refrigerator:
It blew up again, goddammit.  |O
Had my brother hold the trigger pulled while i had my DMM measuring the output along with a current clap on the mains input.
As i increased the voltage the output settled at 19.54V but my current clamp was measuring between 1 and 2 amps idle.
That's about 300W going into my welder somewhere.
My Brother then had the bright idea to release the trigger and pull it again, which instantly blew the welder up. :clap:
I hope that only one MOSFET blew because i only have one spare.
The diodes are shorted out yet again so i guess 150V was not enough.
Anyways i'm off to aliexpress to find some more, at least there's some improvement i guess.

patrick1:
the idea might corrupt your plan abit, - but away... how about a RC LIPO or LION Pack in paralell with the output.... super caps might be ok too.....

btw i love your ambition ... but its verging on insanity...  a home made reliable transformerless? welder.

---  i want too say too, the best arc welding experience i have ever had, is with car batteries, - 24V... it so smooth like butter. so nice.

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