At 08:08 AM 5/5/99 +0100, Steve Thompson wrote:
>
>
Even the peak current for the FWB is alot higher than I'd expect,
>>except you've measured real values that agree fairly well. I'll play
>>around abit to see if I can verify one way or 'tother.
>>
>>Thanks...Phil
>
>I'll try to find time to re-measure too. The Spice numbers stack up with
>data from the 5th ed. RSGB handbook from 20 yrs ago, but that's far from
>a reliable guaantee!
>
Steve, I studied a previously unread section of Flanagan's book that
contains considerable new computer generated data on transformer analysis -
pages and pages of parametric curves. The curves relating various peak
currents vs. several other normalized parameters appear to support your
numbers. They still don't quite produce the same values you have, but
let's say they're "along the same lines" and are certainly much higher than
the figures I quoted in my original message. Oddly, those original numbers
are from the same book and appear to be at odds with the data contained in
the later chapter with the computer generated analysis.
The author says the data was generated with a program called MICRO-CAP II,
which appears to be similar to SPICE from his description of it.
Leakage inductance is a parameter used extensively in the newly generated
data. This was not taken into account in the classic original work by
Schade (1943). Schade's curves are of the course the ones that appear in
the ARRL Handbook as well as others. Including leakage inductance in the
calculations really does add new and useful information.
>
>PS I don't know where you to go to get it, but I'm using PSpice which is
>freeware.
>
Can anyone provide a source for PSpice ??
>PPS I've no axe to grind here - According to Spice using the figures I
>guessed at, the doubler does not deliver significantly lower ripple and
>puts everything but the transformer insulation under greater strain.
>
Agreed, and no ax grinding perceived on this end. The transformer
insulation is not under any greater or less voltage strain with either
rectifier configuration with perhaps one exception : the lower sec.
voltage with the doubler transformer permits less insultion between the sec
winding and core, and sec. winding and primary winding. Layer-to-layer
insulation requirements would be approximately the same in either case (FWB
vs FWD), assuming the same flux density, volts/turn and turns/layer.
The main advantage with a doubler still appears only to be the reduction of
the required mass of the transformer - less copper and paper as has been
stated, and less iron - all of which distills down to lower cost, and
smaller size and weight. Some of this is offset by the cost of higher C
requirements (requirements which often aren't fully met).
Let me know if you come up with anything new.
Phil
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