Re: Recent s.s.t.c work

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Bob (R.A.) Jones" <a1accounting@xxxxxxxxxxxxx>

Hi,
----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Monday, October 31, 2005 10:03 AM
Subject: Re: Recent s.s.t.c work


> Original poster: "K. C. Herrick" <kchdlh@xxxxxxx>
>
> I answer my own recently posted question, which was "I wonder if a
> better feedback scheme would be to feed back from the secondary
> rather than from the primary.  That way, the operating frequency of
> the system would always be at the Fr of the secondary, with the Fr of
> the primary to be adjusted (presumably lower) so as to reach the
> maximum primary current that could be accomodated as a function of
> duty cycle and allowable mains-current.  Does that sound reasonable?"
>

It's been explained a several times on the list but here is an other short
version of what appears to be a commonly misunderstood effect.

When the primary and secondary are coupled via the mutual inductance. the
original resonance (when uncoupled) of both the primary and secondary are
replaced by two new resonances.
This is called frequency splitting.  This occurs in both the secondary and
primary and even if the primary and secondary are not at the same frequency
when uncoupled.
This is a very common property of coupled resonances.

So even if you do arrange for the feedback to be at the original resonance
of the secondary it would not be at either of the new resonances.

To understand the frequency splitting fully you probably need understand the
transfer function of the coupled system. If you look back in the archives
you will find the more detailed explanations. They also give more details of
when it occurs but for the average tuned primary and secondary it always
occurs.

Its also complicated at the start of an oscillation burst because of
transients that die away and are not ultimately present in the CW case.



Robert (R. A.) Jones
A1 Accounting, Inc., Fl
407 649 6400