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Coupling coeff. vs Voltage gain (was Re: Who needs a quenching gap ?)



Original poster: "Marco Denicolai by way of Terry Fritz <twftesla-at-uswest-dot-net>" <Marco.Denicolai-at-tellabs.fi>






"Tesla list" <tesla-at-pupman-dot-com> on 12.12.2000 20:26:42

To:   tesla-at-pupman-dot-com
cc:    (bcc: Marco Denicolai/MARTIS)
Subject:  Re: Who needs a quenching gap ?



>The currents cross zero. The primary voltage touches zero and increases
>again, without a polarity reversal.

Sorry, but in my (MicroSim) simulations do primary voltage DO reverse its
polarity. Why /how it shouldn't?!

So, if I understood well, the instant when both CURRENTS are zero is the total
energy transfer instant, correct?

>Something strange in this. The maximum gain can't exceed sqrt(L2/L1),
>with the two untuned frequencies identical.

Right, but here we consider f1 <> f2

>Test system (just 2 capacitors and 2 coupled inductors, with initial
>charge in the primary capacitor):
>L1=0.1 mH;  C1=10 nF
>L2=100 mH;  C2=10 pF
>k=0.6
>Results in voltage gain of 31.6 (sqrt(L2/L1)=sqrt(1000)=31.6).
>
>Other system:
>L1=0.1 mH * 1/0.735^2 = 0.185 mH; C1=10 nF
>L2=100 mH;                        C2=10 pF
>k=0.546
>This corresponds to f1/f2=sqrt(l2*c2/(l1*c1))=0.735
>A simulation shows that the maximum gain reaches only 27.4.

But now calculate again sqrt(L2/L1)=sqrt(100mH/0.185mH)=23.25 (you did change
L1)

Note that now 27.4 = 1.18*23.25 !! Just as the paper said.

The paper doesn't assume you are varying C1, L1 or other: it simply tells that
for certain combinations of f1, f2 and k (that is L1, C1, L2, C2, k) you can
break the gain rule of sqrt(L2/L1) and get 1.18 times that much.

>I don't know the paper that you mention. Can you put a copy somewhere
>in the web?
>
>Antonio Carlos M. de Queiroz

You can find a zipped version of it at

http://www.saunalahti.fi/dncmrc/th_ccoef.htm (check the last link down)

or

http://www.saunalahti.fi/dncmrc/phung.zip

The quality of the scan is pretty bad: there are also some typing errors (at
least in one place "1" is confused with "T").
Beware of that. I have also got a postscript version of it (about 800K zipped)
which is much more readable. If you can
open/print postscript let me know and I'll email to you directly it.