Re: drsstc - catastrophic failure!

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "K. C. Herrick by way of Terry Fritz <teslalist-at-qwest-dot-net>" <kchdlh-at-juno-dot-com>

I don't know what that "Hello everyone" paragraph means unless it's curse
words.  With "microsoft" in it, I guess it has to be...

So welcome to the club, Jimmy.  I just blew out half the IGBTs I'd
incorporated into my re-done s.s.t.c.  I'm within a whisker of giving up
on s.s. completely.  Primarily because it's impossible to get scope
probes near the circuits while the whole thing is running: can't
trouble-shoot it with the pedal to the metal.

Except for the mains-frequency high voltage, I'd be inclined to give in &
go for the tried-&-true; but I hate 60 Hz H.V.

Ken Herrick

On Thu, 17 Apr 2003 22:10:59 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
 > Original poster: "jimmy hynes by way of Terry Fritz
 > <teslalist-at-qwest-dot-net>" <chunkyboy86-at-yahoo-dot-com>
 >
 >
 > Hello everyone,<?xml:namespace prefix = o ns =
 > "urn:schemas-microsoft-com:office:office" />
 >
 >
 >
 > A few days ago I had it running at 280 volts, pulsing the primary
 > coil and
 > capacitors for 2 cycles (400 amps peak) every second. But now it is
 > dead.
 >
 > I was running it with 150 ohms in series with the ac hot, and it was
 >
 > working fine up to around 280 volts. At around 280 volts, the
 > microcontroller started freaking out every few pulses and sometimes
 > shut
 > off. I am almost certain it picked up noise from the primary coil a
 > few
 > inches away. I then looked at the power line to the micro. It was
 > all over
 > the place from 0 to six volts, following the 60khz current in the
 > primary.  I had forgotten to add a decoupling capacitor. That was
 > stupid,
 > as it could have saved my project. I will put some fat ones on
 > before
 > running it again ;-).
 >
 > I was just about to turn the thing off, when I heard a loud pop, and
 > the
 > dog ran into the bedroom to hide under the table  After I turned it
 > off, I
 > looked over and saw smoke.  If the capacitor bank was at 280 volts,
 > there
 > were  88 joules in there. The pop killed seven out of the eight
 > IGBTs that
 > I was using! These things are tough, but not indestructable.  I can
 > find
 > ways to break anything ;-). The IGBTs are all in one piece but every
 > pin is
 > shorted together. I think that happens when they are over-volted. My
 > guess
 > is that the microcontroller got confused and told all of the IGBTs
 > to go on
 > at the same time (I have no shoot through protection).
 >
 > I might try some brick IGBTs, because my assembly was pretty much
 > destroyed, only the diodes are  left on the heatsink. There are some
 > on
 > ebay now that look fast enough, so I might snatch them. I am also
 > trying to
 > contact Powerex about their complete Pow-R-Pak modules. I want to
 > finish
 > this thing!
 >
 > I've also gotten advice from Bill Reass, who designed a resonant
 > pulse
 > transformer for physics research at Livermore Labs.
 >
 >
<http://arxiv-dot-org/ftp/physics/papers/0008/0008125.pdf>http://arxiv-dot-org/ft
p/physics/papers/0008/0008125.pdf
 >
 > I want dibs on his power supply when they scrap it out :-). They're
 > pulling
 > 10MWatts peak and 1MWatt average power!
 >
 >
 >
 >
 >
 >
 > Jimmy
 >
 >
 >
 > Do you Yahoo!?
 > <http://us.rd.yahoo-dot-com/search/mailsig/*http://search.yahoo-dot-com>The
 > New
 > Yahoo! Search - Faster. Easier. Bingo.
 >
 >
 >
 >