Re: OLTC Thoughts

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

Original poster: "Wall Richard Wayne by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rwall-at-ix-dot-netcom-dot-com>

Terry,
 
> The IGBTs have big powerful anti-parallel diodes in them already ;-))

Excellent, do you know the speed (Reverse Recovery time) of these diodes? 
If they're too slow you may need to add supplemental fast diodes.  Your
fast CE MOVs or snubbers are also good ideas.

> 
> >Have you calculated the resonate oscillatory frequency of the primary
tank
> >without the switches?  Also consider moving the switch(s) outside the LC
> >tank altogether to allow the tank to oscillate freely and transfer even
> >more energy before you electronically quench it.  I'll leave these design
> >thoughts up to your fertile electronics imagination.
> 
> They are fairly well outside it now.  

Your schematic places the IGBTs right in the LC tank circuit.  See
http://hot-streamer-dot-com/temp/OLTC8-10-01.gif et subsequent.

Another consideration is that with ten IGBTs and ten 4.7 mF caps, not only
does turn on have to be right on the money, BUT turn off has to also be
exactly the same for all IGBTs.  Post firing, as the tank oscillates and it
is also charged by the PS, differences in IGBT turn off timing will affect
residual charge imparted on each 4.7 mF cap.

What is your proposed IGBT firing rate and dwell time?

RWW
 
--- Richard Wayne Wall
--- rwall-at-ix-dot-netcom-dot-com