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Re: Paralleled Primaries / Separate Drive Circuit - SSTCs ? ? ?



Original poster: jimmy hynes <chunkyboy86-at-yahoo-dot-com> 

Hi,
--- Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: Terry Fritz
 > <teslalist-at-twfpowerelectronics-dot-com>
 >
 > Hi Captain,
 >
 > At 01:31 PM 9/17/2003 -0400, you wrote:
 >
 >
 > >Has anyone explored the use of paralleled primaries
 > in SSTC use.
 > >
 > >For example, say I had two SSTC full-bridge power
 > supplies each with
 > >their own dedicated primary winding and of course
 > both supplies
 > >switching frequency are synchronized.  Now i take
 > those two independent
 > >windings and use them either interweaved, or
 > top/bottom configurations
 > >and run both at the same time.
 > >
 > >Neglecting losses, I would assume that two 5kW
 > power supplies combined
 > >like this would appear like one 10kW supply to
 > >the secondary coil.  Is this correct???
 >
 > Yes!

The power supplies will be able to handle 10 kw, but
if the primary coils are tightly coupled, then it
would be the same impedance, and therefore, same
power.
 >
 >
 > >If so, perhaps this is a way to increase power even
 > more to a SSTC when
 > >the maximum impedance of one coil limitations
 > >are met.
 >

If the coupling is 1, then there is no difference, and
it acts like one turn. It wouldn't even help current
share if the coupling is perfect. Another way of
thinking about it is that both inputs would have the
same voltage, so it can't tell if it's being powered
from one or two drivers. If multiple primaries had
this effect, I would want to see one with a litz wire
primary ;-)

You would want to space the primaries out, and
probably drive it from one driver. If you drive it
from two, one will couple better than the other, that
one would pull more current.

 > The only caution I would have is that the two
 > primaries will strongly
 > couple to each other.  Thus, you need to open
 > circuit one while the other
 > fires.
 >

I think he was talking about synchronizing them, and
running them at the same time. It shouldn't be too
tough. It would be just like paralleling some MOSFETs.

 > Cheers,
 >
 >          Terry
 >
 >
 > >Suppose I had four independent synchronized SSTC
 > drivers with four
 > >independent primaries . . . Hmmm . . . . could
 > >get interesting!
 > >
 > >The Captain
 >
 >


=====
Jimmy