RE: 48kW DRSSTC

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Steve Conner <steve@xxxxxxxxxxxx>

> This
> is what I want to do with the 48Kwatt coil, all on
> slice cards, one
> fails, pull, drop in new and keep sparking!

So what exactly would you be thinking of putting on
slice cards? Would you build, say, ten 5kW converters
instead of a single 50kW unit, and combine the power
from them? Do you intend to do that with the
rectifier, or the HF inverter, or both? It sure would
be interesting to see how that turns out!

I thought about doing it, but I realised I would end
up spending so much on PCB fabrication and card cages.
It seems a lot more economical to just use one set of
the biggest IGBTs I can get my hands on (which would
be CM600s I guess) on a huge heatsink, with an array
of honkin' big electrolytic caps strapped to them.

If I really get power crazed I can always build
several of these large bridges and combine the power
output from them into a single Tesla resonator, in
some way that I've yet to figure out. But even four
CM600s, or two of the CM300 half bridges for that
matter, can probably produce bigger sparks than I have
room to fire off.

You might be interested in the DRSSTC driver I
developed. I'll be honest, I have a vested interest in
getting as many people to use it as I can. The more
people use it, the more bugs I'll find ;-)

It was done with museum type coils in mind, so it has
all sorts of protection features that would come in
real handy on a big coil. Finn Hammer and I have built
7 DRSSTCs with this driver circuit, and we have had no
IGBT failures in service yet.

I'm currently working on some add-on gate drive
amplifiers for it that will allow you to drive almost
any number of IGBT bricks. At the moment I'm wondering
whether to put desaturation and gate drive failure
protection on these add-on boards. It's theoretically
nice, but it adds enough complexity and extra places
for EMI to get in, that it might actually end up
reducing reliability.

There is also a plug-in "solid state variac" board
that will drive SCRs for voltage control of a
rectifier or doubler, but I only have a prototype of
that built on perfboard.

The schematics etc. are on my DRSSTC page-

http://www.scopeboy.com/tesla/drsstc/

Steve Conner