Re: Triggering Stacked IGBTs

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Finn Hammer <f-h@xxxx>

Steve,

You are in luck, because this was made possible for the average 
hobbyist just a couple of months ago, due to Terry Fritz`s 
groundbreaking sisg topology, and to my own addition of a scr and a 
trigger transformer to each sisg section. And some trivial pulser circuitry.

Just go back in the archives a couple of months and look at the 
triggered sisg thread.

There is enough info to get you going.
http://home5.inet.tele.dk/f-hammer/tesla/sisg/sisg.htm
Not updated, but I move on rapidly, got a lot to learn myself, you see.....
Also see:
http://4hv.org/e107_plugins/forum/forum_viewtopic.php?17454
http://4hv.org/e107_plugins/forum/forum_viewtopic.php?18117

The fact that each section is sisg triggered as well as triggered by 
a pulse transformer means that if any of the pulse transformers fail 
to trigger at the right time, then the sisg will step in and do it.
I see the sisg as a static safety gap, and a darn good one too!

Cheers, Finn Hammer

Tesla list skrev:
> Original poster: "S&JY" <youngs@xxxxxxxxx>
>
> I am looking for ideas on practical and not overly expensive ways to 
> trigger a stack of IGBTs.  For example 10 1,200 volt IGBTs in series 
> to take the place of a spark gap.
> The SISG (SIDACs) scheme is good, but I want more control.  I would 
> like to be able to externally vary pulse rep rate, pulse width and 
> the DC voltage to the stack independently.  I suppose I am after a 
> poor-man's variant of a klystron modulator such as used in particle 
> accelerators.
> One method is to use fiber optic coupling to photo detectors 
> controlling each IGBT.  I have read these are susceptible to 
> electrical noise.
> Other methods use pulse transformers, e.g. modulated several mHz 
> inputs and rectify the outputs to control the gate.  Or use pairs of 
> pulse transformers to trigger a flip flop on and off to control the 
> IGBT gate.  Of course, whatever scheme is used must trigger all the 
> gates simultaneously.  And the trigger circuits on the IGBT side 
> must derive their power from the main DC power to the IGBT stack (to 
> avoid the need for isolated power supplies).
> Can some of you steer me to a source of ideas?  Better yet, can any 
> of you report your practical experience triggering series connected IGBTs?
> Thanks,
> --Steve Y.