Re: DRSSTC stablity/ closed loop response

["Tesla list" <tesla@xxxxxxxxxx>]

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

Hi Terry,

Do you still have MathCAD 2000? If you do I can send you a file/s that plots
the frequency responses, input impedance etc. You can play with the
parameters and perhaps get a feel for it. I also have a file some where that
shows how the frequency splitting occurs graphically again you can play with
the parameters to get a feel for what's going on. If you think anyone else
would be interested feel free to put them on your site. Most of them have
little or no comments but they may be self explanatory.

I think the key to understanding the frequency splitting is to understand
that its the reciprocal impedance of the secondary is referred to the
primary or visa versa.  I think I posted a hand waving version of it a while
back.

Robert

----- Original Message -----
From: "Tesla list" <tesla@xxxxxxxxxx>
To: <tesla@xxxxxxxxxx>
Sent: Tuesday, February 01, 2005 12:19 PM
Subject: Re: DRSSTC stablity/ closed loop response


> Original poster: Terry Fritz <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi Bob,
>
> At 10:25 AM 2/1/2005, you wrote:
> >Hi all,
> >
> >I thought I would look at how stable a feedback system is that is
oscilating
> >at the centre frequency .  So I looked at the closed loop response
assuming
> >everything is linear including the feedback.
> >
> >My first go at it with secondary voltage feedback with and with out 90deg
> >phase shift shows two poles approximately at the up and lower split
> >frequencies.  Which I think means that a DRSSTC will eventually oscillate
on
> >one of those frequencies even if it starts of at the mid point.
> >
> >I will next try primary current feedback (much more work but that's the
one
> >I am interested in) but I expect the same result.  I think the bottom
line
> >is the mid frequency is an unstable operating point and therefore the
system
> >will always move away from it to a stable operating point which are the
> >split frequency poles if you give it sufficient time.
> >
> >Robert
>
> Cool!  When you get the primary current one figured out, explain it too me
> since I seem to be the last one to understand what everyone is talking
> about with these poles and f1 vs. f2 frequency things 0:-p
>
> Cheers,
>
>          Terry
>
>
>
>
>
>