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Registered Member #2919
Joined: Fri Jun 11 2010, 06:30PM
Location: Cambridge, MA
Posts: 652
Beam tetrode wrote ...
Hi sir, nice work - can you show us what transformer are you actually using? It's hard to tell from your pictures.
IGBT's are pretty tough bastards as long as they are not let to overheat. I've ran a fullbridge of 30N60's up to about 25kVA with hard switching, for a while at 100kHz and they lived.
I think it was Steve Ward who initially spread the rumor of how horrible hard switching is compared to SLR topology. While it certainly is a benefit for capacitor charging, I'm not sure what it does when load are arcs - resonant frequency changes depending on arc length!
On the other hand, I think Steve mounted his igbt's with a single screw and sil pads. That might be the reason why they initially blew up.
Marko
Its not just about overheating though - unless your bridge is *very* well laid out, when hard switching a hundred amps the ringing from the bus inductance will blow up your transistors.
On the other hand， can i take a look at your 25KVA arc？I think it is a very strong
Hi guys,
Well sorry for not being clear, the 25kVA mark was a SSTC, not a flyback driver! And it does not produce at all that spectacular sparks, considering it's CW. Here be the video:
I expected the IGBT's to blow on that run, but they are still alive today, and seeing less than half of the load they did on that run since I switched to a resonant topology!
I'm much more surprised about how your flybacks held out with this sort of punishment. I know there are some others who pushed flybacks into over a foot long arcs but those surely didn't last long.
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3KW flyback transformer CCPS{
