High voltage diode blowing mysteriously
in [Design]
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From: m II on 6 Jul 2010 00:41 Nummy Buns LivercupLover wrote: > IDIOT. > Grow up, idiot. > You are an idiot Constantly repeating what your Father called you isn't helping at all. ============================================ But I say to you that everyone who is angry with his brother will be liable to judgment; whoever insults his brother will be liable to the council; and whoever says, �You fool!� will be liable to the hell of fire. Matthew 5:22 ============================================ father mike
From: Copacetic on 6 Jul 2010 00:58 On Mon, 5 Jul 2010 23:20:23 -0500, "Tim Williams" <tmoranwms(a)charter.net> wrote: >"legg" <legg(a)nospam.magma.ca> wrote in message news:6p7536hhm12k3oggp0dsj6te2b8556n7r0(a)4ax.com... >> If the currents are unbalanced, you may need freewheeling rectifiers >> to ground, before the choke, on both sides. > >Ah, interesting. > >The dead time voltages are near zero (give or take a small amount of squiggle), so it seems to be okay. > >Tim Experiment with the transformer core gapping to massage dead time. That is likely one of the elements you need to fix this issue. We have gapped cores between 0.5 mil and as much as 50 mils for one weird configuration. Zero gap is bad, and we usually got prime results with between 0.5 mil and 10 mils. Truly, if your transformer is not gapped, it should be, even if only slightly.
From: StickThatInYourPipeAndSmokeIt on 6 Jul 2010 01:10 On Mon, 05 Jul 2010 22:37:56 -0600, m II <sc(a)in.the.hat> wrote: >But Archie, you LOVED inhaling my little anal 'love puffs' just >yesterday. Have you found someone else? You are so retarded that you quote scripture in the same post that you jack off at the mouth with this stupid horseshit in. You're a real prize, you are... yeah... sure... Better hope you never find yourself in one of my confessionals.
From: m II on 6 Jul 2010 01:18 StickThatInMyAssandPUMPit wrote: >> Mike, I love you and want your children. I've arranged a 'loan' of >> the requisite organs from my sister. She's adopted, so it doesn't >> matter. Thank God for displaced earth quake victims, I say! >> I'd like to thank you for bringing back those lost memories of my >> Father. He DID call me idiot on a daily basis and now I'm doing it >> to others. Thank you for saving my Eternal Soul. > ============================================ > But I say to you that everyone who is angry with his brother will be > liable to judgment; whoever insults his brother will be liable to the > council; and whoever says, �You fool!� will be liable to the hell of fire. > > Matthew 5:22 > > > http://www.photosforsouls.com/hells-fire-duncanlong181.jpg > ============================================ > > > > father mike
From: Joerg on 6 Jul 2010 09:43
Tim Williams wrote: > "Joerg" <invalid(a)invalid.invalid> wrote in message > news:89fb8lF7cnU1(a)mid.individual.net... >> Best to put them on the schematics. 47pF is almost nothing. Are you >> sure this quenches ringing enough? > > Yes, it gets hardly a cycle before the ringing is too weak to see. > >> Possibly, because at 75nsec trr these are fairly slow. > > Slow!? Come on, I know you love dabbling with MHz stuff, but gimme a > break, this is only 120k after all! > 75nsec still is 0.45% of each phase. Quite a lot. >> Since you probably don't want to spring for four of those Cree >> super thingamagics which would totally raid the beer kitty, why the >> 2x10mH common mode choke? Tried separate chokes yet? > > Hmm, "common mode" is a funny way to put it. The negative rail is > inverted, so I guess it should be "differential mode". > > I used that since everyone else uses multiwinding chokes in forward > converters. Two chokes would take up more space and be more trouble > to wind; this is only one part. > > I'm not buying them and I'm not mass-producing them, so don't bother > going all Joerg on me. ;-) > Well, then wind another one :-) >> Of course, if you came into a wad of cash: >> >> http://www.cree.com/products/pdf/C2D05120.pdf > > With 45pF at 200V (probably with high Q), I'll need even bigger > snubbers. The transistors might not appreciate trying to push around > the 455pF "not-recovery" capacitance, either. Actually, 28nC charge > is like 0.5A * 50ns reverse recovery, so they'd be just as bad! The > only difference is, you get the capacitance back each time, whereas > the reverse recovery is heat each time. > .... and they can be bolted to a heat sink. But you said yours don't get hot so that's weird. > Anyway, even peak Irr were 0.5A, that's roughly 75ns * 0.5A * 4 > diodes * 120kHz * 2/cycle = 36mA effective reverse leakage. At 250V, > that's 9W, or 2.25W/diode, but recovery occurs at a few volts, not > all 250, so the real power is something else. Evidently it's fairly > small, because the diodes don't seem to heat up until the one dies... > At 2.25W per diode these would get friggin' hot ... phssss ... OUCH! What is more dangerous is if you had current spikes into the 2-digit range which is only rated for non-repetitive. > > No one makes 1A SiC rectifiers? What's up with that? > Not for those kinds of voltages, and SiC is still expensive. -- Regards, Joerg http://www.analogconsultants.com/ "gmail" domain blocked because of excessive spam. Use another domain or send PM. |