[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index]

Of notches, coupling and frequency splitting



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

All,
In an attempt to find an explanation of the subject that I can understand, I modeled a tesla coil in Orcad. It has Cpri=33nF, Lpri=77uH Csec=33pF Lsec=77mH and K12=0.0688836105 So that it should have it`s first notch after 7,5 primary cycles.

A plot of the primary and secondary currents looks like this:
http://home5.inet.tele.dk/f-hammer/notches.jpeg
and a FFT has the expected appearance:
http://home5.inet.tele.dk/f-hammer/notchesFFT.jpeg

IOW, both coil systems oscillate at a clean 100kHz if by them selves, and if coupled, they are, by popular convention, assumed to oscillate at 2 frequencies simultaneously. I guess they do so, in the frequency domain, but I live in the time domain, so I measured the time of each peak , to see what comes up.

I get the list shown below, which shows that for the vast majority of the time, both coils are oscillating very close to 100kHz. Only at the times where there is little energy in the system, around the notches, do they oscillate faster, and I think this is because they have to reverse the phase, from giving to taking, but I am not sure about this.
I cannot see the low pole in these numbers.
I offer these numbers for all to ponder, because I feel it may help break the notion, that the coils oscillate in a magic unpredictable pattern. It may not be so complicated.

Of course, this is a disruptive coil, without breakout, with both coil systems tuned to the same frequency.
This is not the case with the typical DRSSTC, or so I have heard.
I have full understanding that people still guard their respective tuning procedures as a personal treasure. But I also think, that the quest for the next generation of DRSSTC drivers has to rely on an openness about tuning, which at least "I" am not part of yet.


Explanation:
1row,  time-sec-current = time for pos. peak and neg. peak of secondary current
2row, Incr = time period from peak to peak of secondary current 3row, "freq" =Inverse of time period, to imply a frequency relationship.

I cannot get the table to show up in proper format, so here it is:
http://home5.inet.tele.dk/f-hammer/notchtable.jpeg

Is this new, wrong or rehash?

Cheers, Finn Hammer