Another way to question this:
How can you be certain the secondaries will be in phase
with each other? They most certainly won't be if they
aren't identically wound (hard to do even when you wind
on the same core).
And what will you do to prevent the fields from interacting
to buck or boost in close proximity to each other? You
will have to mount them broadside and isolate these
transformers with rectifier stacks, or spend a great deal of
time fiddling with the windings. You may still have to unwind
a little on the higher voltage winding (after the stack) to bring
the current up on the lower voltage winding.
Also you will have to insure that the PIV of the stacks aren't
exceeded. And here is the kicker: If the outputs are not nearly
in phase, each winding will be carrying greater than half the
load at some part of the cycle! Consider that if the windings
are exactly 0 or 180 deg out of phase with full wave, then no
problem. Ok if exactly in phase with a half wave stack. But
each transformer will carry the full load when the other isn't!
At least with half wave the duty cycle will be lower. Of course
the size of your capacitor bank and the inrush current will have
to be looked at too.
Jim, ac6tk
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