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Re: El Supremo
Original poster: "K. C. Herrick by way of Terry Fritz <twftesla-at-qwest-dot-net>" <kchdlh-at-juno-dot-com>
Thanks for the tips (& the opinion)! I should have looked for the "-D"s
at irf-dot-com rather than in my (old) paper-copy DigiKey catalog--or at
digikey-dot-com. Without those diodes I can plan for 1-2 more IGBTs in each
group in case they'll be needed to handle the peak current. As to the
IRG4PC50FD, mighty it may be, but at 8 KHz & not at 140, I fear. Its
gate charges & turn-off delays are over twice those of the IRG4PF50W.
I do plan to directly screw down the transistors--and solder the lead
just for that little reduction in R.
I'll add these features that I forgot to mention:
1. El Supremo can be checked out, at lower voltage, with just a few
IGBTs and just a few capacitors; nothing changes as to frequency,
coupling to the secondary, etc. (perhaps that's obvious).
2. I think, for modeling purposes, just one capacitor can be
incorporated for each quadrant, perhaps at the middle & with 1/8 of the
total primary L and R connected either side of it.
3. And here are 7 functions of the copper pipes I can think of:
3.1 conduct the primary's rf current via exceedingly low L and R
3.2 physically support the capacitors, IGBTs & other components
3.3 heat-sink the transistors
3.4 offer a relatively large, smooth radius facing the secondary coil,
reducing the electric field there
3.5 conduct mains power to the capacitors
3.6 provide passages for forced-air cooling if ever indicated
3.7 look impressive, especially when chrome-plated.*
* leaving un-chromed spots for soldering the capacitors, of course
On Sat, 14 Sep 2002 14:16:19 -0600 "Tesla list" <tesla-at-pupman-dot-com>
> Original poster: "Terry Fritz" <twftesla-at-qwest-dot-net>
> Hi Ken,
> It looks great! I can't see any problems with it. I do have one
> suggestion. Instead of using IRG4PF50W IGBTs, you could use
> IGBTS that have the reveres diode built in.
> IRG4PF50W $6.12 + HER305 ($0.58) = $6.70
> IRG4PF50WD $7.11
> DigiKey has them but maybe you have a cheaper source for the others
> already have a bunch. Just got to www.digikey-dot-com and type in
> and links to both popup. BTW - Ignore the current ratings and such
> DigiKey's descriptions since there are errors. Go off the data
> If your voltages will be below 600V, maybe you could use the mighty
> IRG4PC50FD. Only $8.74 but 70A and 280A Peak! They also have lower
> for greater efficiency too. BTW - I notice the prices on IGBTs are
> steadily dropping (copper on silicon is starting to get "old" so
> they can't
> charge as much for it) :-)))
> The back of the IGBTs is a direct collector connection so you could
> them direct to the collector plate with no silpad, just
> grease(best), or
> one of those foil conductive pads (very good heat transfer).
> Keeping the
> IGBTs as cool as possible really helps.
> At 11:31 AM 9/14/2002 -0700, you wrote:
> >I have proposed a new solid-state Primary apparatus, "El Supremo",
> >on my previously-described Entertainment Machine and strongly
> >by Terry Fritz' OLTC design. See prior postings and also the
> >> http://hot-streamer-dot-com/temp/tch2.gif. plus the accompanying
> >schematic at
> >> http://hot-streamer-dot-com/temp/tch2drv.gif. I'll repeat here
> features I
> >see as important & then refer you to two more posted drawings
> showing how
> >I envision the apparatus to be assembled.
> >1. Very low impedance: just 1 equivalent turn.
> >2. Highest quiescent voltage to ground = peak of mains voltage.
> Safe as
> >a toaster (well...maybe almost).
> >3. Non-resonant: operating frequency is controlled electronically
> and is
> >not a function of the associated energy-storage capacitance.
> >4. Current-switching is by means of IGBTs. Each IGBT sees only a