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RE: Sold state IGBT disruptive coil spark gap idea
Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
Hi Gary,
At 04:40 PM 4/29/2006, you wrote:
As one who's never toyed with DRSSTC's, I have a dumb question that's
probably been discussed previously, but -
What is the performance-consequence to completely eliminating the
concept of quench, and permitting as many pri-sec trades as it wants?
It's a pretty complex question. The electronic gap I am thinking of
has no quenching (at the moment). Maybe it could be added later...
In the case of the DRSSTC, energy is constantly added to the system
during the firing cycle. Unlike a conventional coil that only has
the energy initially stored in the primary capacitor, the DRSSTC is
constantly putting power into the system as long as it is enabled.
In my case, I "control" the "power" of my DRSSTC by varying the
on-time. As I increase the on time, I can "feel" the
notches. Instead of the power increasing perfectly smoothly, there
are dead and hot spots as one goes through the notches. But the
power always increases until it seems like it just reaches a maximum
point. The DRSSTC can turn off at any time, but the primary system
can still take back power are restore it in the buss caps. I think
Jimmy or Steve tried to do real quenching once with DRSSTCs but they
said it just was not worth it.
For my conventional coils, I always adjusted things to put as much
power as possible into the first notch. I used streamer load models
to determine that all the power would probably be used up in the
first notch with a streamer load anyway. By playing with the
coupling, I can drag out the first notch time to insure that. That
is why my coils tend to have lower coupling than most. I sometimes
referred to this as "auto quenching" but I think I am the only one
that ever really understood what I meant there. But basically I
reduced the coupling to put as much power into the first notch and
the system was pretty much drained by the time the second notch
occurred anyway. I use rotary gaps, but I am not sure my coils ever
"trapped" energy in the secondary with perfect quenching performance at all.
If the electronic gap works, it will be interesting to see how the
notching and quenching works out. Right now, I am not worried about
it at all, but it might need some adjustment to compensate for it.
Another factor is how lossy the primary system is. If there is a lot
of loss in the primary circuit, then quenching should be much more
important. LTR coils tend to hove lower losses as do some big coils
with very heavy wiring. MMCs have also reduced primary loss
considerably. In most cases, the gap itself is the big loss and this
gap is more efficient there.
It seems to me most good quenching gaps do it at the expense of high losses...
So now you know what "I" know. There are many variables so it is
really "hard to say".
Cheers,
Terry
Regards, Gary Lau
MA, USA
> Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi All,
>
> I was up late last night working on an idea for an IGBT replacement
> for a conventional coil spark gap. I woke right up at 2PM this
> afternoon (semi-retired people can do that :O))) and started getting
> some parts and wrote a paper up on it here:
>
> http://hot-streamer.com/temp/Sidac-Gap-1.pdf
>
.........