Re: El Supremo

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

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

Ken

On Sat, 14 Sep 2002 14:16:19 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
> 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 
> IRG4PF50WD
> 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 
> or
> already have a bunch.  Just got to www.digikey-dot-com and type in 
> "IRG4PF50W"
> and links to both popup.  BTW - Ignore the current ratings and such 
> in
> DigiKey's descriptions since there are errors.  Go off the data 
> sheets.
> 
> http://hot-streamer-dot-com/temp/irg4pf50w.pdf
> http://hot-streamer-dot-com/temp/irg4pf50wd.pdf
> 
> 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 
> Vce
> 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) :-)))
> 
> http://hot-streamer-dot-com/temp/irg4pc50fd.pdf
> 
> The back of the IGBTs is a direct collector connection so you could 
> bolt
> 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.
> 
> Cheers,
> 
>         Terry
> 
> 
> 
> 
> 
> At 11:31 AM 9/14/2002 -0700, you wrote:
> >I have proposed a new solid-state Primary apparatus, "El Supremo", 
> based
> >on my previously-described Entertainment Machine and strongly 
> influenced
> >by Terry Fritz' OLTC design.  See prior postings and also the 
> schematic
> >at 
> >> http://hot-streamer-dot-com/temp/tch2.gif.  plus the accompanying 
> driver
> >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
> snip.......
> 
> 
> 
>