Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx> Hi Dan,I can't tell you how MUCH this HELPS!!! :-)))) Knowing that the buss is 400V (+- 200V in the model case) and the arcs are occurring in the ~100uS time range changes a number of "guess" variables and fixes MANY things :-))))))) The models is "locking on" now ;-)))) Bwahahahhaha!!! Your coil has a high quality factor that I can "advantage"... No definition... But it means something to "me" ;-))) I was estimating that way low before... Sort of an if all limits are removed, how "high could it go" thing... You probably know what I mean...
I am very interested in top voltages as from an antenna since that will define how long the streamer persists and when it "goes out"... I can set streamer "turn off" as I please but I don't know what is "right"... I and Steve have noted this "recharging" effect:
http://drsstc.com/~sisg/files/scantesla/DanCoil-01.gifProbably primary current or "whatever" will show this too... Interested in measured coil power too since that further defines things ;-)))
That tells a lot about when the streamer "goes out" while there is "still a little energy" left in the coil. Many options for predicting that, but I don't know "which one"...
I think it was Steve Ward or Jimmy who re-enabled the drive during the bang if the current went low... That is trivial to model but can be "noise" if that is not the "real situation" ;-)
Weeeeeee!!!Once I get the new model working, you won't need the "real" coil anymore :O)))))
BTW - I am getting best tune at 7.46uH primary rather than the 7.1 or 7.2 range (700 amp limit) if that means anything (probably not)... The program has an obnoxious habit of being able to "tune" far better than reality... It likes to "plan" streamer to ground hits at low primary circuit power nulls for best advantage. More easily said than done in the "real world"....
Cheers,
Terry
At 08:55 PM 6/14/2006, you wrote:
Terry,
Not sure how much arc length is reduced from reducing pulsewidth in this
set-up. Visibly, it appears arc length remains constant all the way down to
about 100us. I believe this is around the point where most of the energy
has already been taken from the DC bus capacitors. The current waveforms
would be indicative of this, although i'm still just collecting data (not
analyzing) at this time.
The only time i was really current limiting was during the first iteration
of my tuning study (1.00 turn from top as designated on my spreadsheet).
Current limit occurred during most ground strikes (at full voltage)
Yes, i am using a half-bridge, and my rails are approximately 0V and 395V.
With my new driver, when current limit is hit, the system will re-enable on
the very next interruptor pulse, so its very fast to re-enable.
But in summary, other than the 3 highest arc levels as shown on my first
iteration (1.00 turn from top) on the excel sheet, current limiting was not
occurring.
Hope this helps.
Dan
Hi Dan,
So you decreased the pulse width but increased the current limit to
go from 34 to 48 inches. Normally I would think decreasing the pulse
width would lower the coil power and make the streamers shorter
regardless of the current limit. Perhaps the coil is arcing far
early so it never used all the 300uS pulse width anyway ?
When the coil arcs to ground are you hitting a current limit then ?
I assume you are using a half bridge so the buss voltage lower rail
is 0 and the high rail is 340 ?
When you hit a current limit, how long does the coil shut down or
timeout? Do you turn back on "instantly" when the current drops or
do you put it to sleep for say 1/2 second ?
As you know I am up to something and these issues popped up.
:-)) Thanks so much for sharing such great info!!
Cheers,
Terry