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

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cur8xgo:

--- Quote from: Refrigerator on June 23, 2019, 04:46:24 pm ---
--- Quote from: cur8xgo on June 23, 2019, 02:54:32 pm ---
--- Quote from: Refrigerator on June 23, 2019, 01:15:32 pm ---
--- 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.

--- End quote ---

Ya I dont think you will have an issue getting rid of 50W from TO247

--- End quote ---

Don't forget i have two diodes in parallel.

--- End quote ---

Ya even easier

I've been doing it at 125A to 150A through TO-247 50% duty cycle (full bridge) for 30 to 60 seconds at a time dozens of times. The heat sinks arent even that big maybe 5-10 sq inches? There is forced air but its about a foot away and is cooling the switches first. They heat sinks get warm but not hot. I have not yet measured junction temperature or calculated the heat sink efficiency to see if its reaonable but it definitely works so far. 0.54V @ 155A btw (per leg of FB)





Refrigerator:

I thought up a pretty good way to get the most out of my diodes.
Basically since the weird TO-247 diodes came in a package that's meant for electrical isolation i decided to solder the diodes straight to a copper plate and then bolt the plate to a heatsink, which i pulled from a Dell Dimension.
This way the diodes will not only dissipate the heat better but they will also pass current through the aluminum heatsink.


strawberry:
https://www.edaboard.com/showthread.php?57813-SWITCH-MODE-ARC-INVERTER-WELDER-SCHEMATIC/page2&p=862700&viewfull=1#post862700 arc welder with deflection ferrite core

Refrigerator:
After some fiddling i have the rectifier diodes sorted and IGBT gate drive sorted as well, only a few finishing touches left.
Next will be the GDT, but before that i think i'll remake the TL494 board. Keeping the ATX PSU board as a control board seemed like a good idea at first but i might as well go all in and remake it on some proto-board. The TL494 datasheet is a little confusing at first but i think i have it figured out.
I also remembered that i have a Delta fan from a Dell dimension, 1.6A at 12V makes 19.2W so it ought to move some air.  :)


--- Quote from: strawberry on June 25, 2019, 01:20:37 pm ---https://www.edaboard.com/showthread.php?57813-SWITCH-MODE-ARC-INVERTER-WELDER-SCHEMATIC/page2&p=862700&viewfull=1#post862700 arc welder with deflection ferrite core

--- End quote ---
Exactly what i was looking for, but they mention that the core loses inductance after some time, perhaps it's heat related?

strawberry:
MIG/HF TIG 200A inverter
3phase
UC2834 current mode controller with built-in gate drivers
half bridge 40A IGBT 0.66mJ@150 1.6V heatsink SK442-100
E65 CF297 2 sets in paralel ( dont know if they are good cores)

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