RE: Pushing the IGBT Envelop

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

Original poster: "Steve Conner" <steve.conner-at-optosci-dot-com> 

 >However, an H-Bridge plan wouldn't be cost-effective for the ALF since it
 >requires 4X the silicon for the same primary peak current and voltage swing

I appreciate this, but so far (as Steve Ward already said) the findings are
that the DRSSTC needs about 1/8 of the peak primary current that an OLTC
does, for a given spark length. So it all comes out at least even, if not in
favour of the DRSSTC.

Steve, Jimmy H. and I have been engaged in a "Battle of the Coil Topologies"
for the last year or so, and the DRSSTC has come out the clear winner in
terms of "Feet of spark per buck spent on silicon".

I am running my OLTC primary circuit at 1kV and 5000A peak, and getting a
bang energy around 8J and sparks just over 6ft. Now compare that with Steve
who runs his H-bridge at 700V and 1200A peak, and gets 11ft sparks.

In fairness I must mention that you don't get something for nothing. The
DRSSTC has a lower peak current but it goes on for a longer time. Hence,
Steve's IGBT bricks see a much higher I2t than mine. Mine are on something
like 90 A2s (amp-squared-seconds) out of an available 2800. Steve's run
about 220 and they are rated for 360 at a case temperature of 25 degrees.


 >timing errors or cosmic-ray induced firing
 >of IGBTs can hard-short the DC mains

Indeed. The only thing the OLTC has in its favour is that (at the present
state of the art) it's less likely to explode violently.

Steve C.