Re: SSTC DC blocking caps

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: dhmccauley-at-spacecatlighting-dot-com 


Actually, this is not exactly correct as well.
DC blocking capacitors are used in bridge circuits to prevent "core-walking"
(and ultimately saturation) of the output transformer.  This is typically
only used for half-bridge circuits where any
imbalance in the push-pull type configuration of the half-bridge adds any
type of DC bias to the output transformer.  However, in full-bridge
circuits, imbalances are almost always equalled out
due to the topology of the full-bridge.   For what we are doing, you really
don't need the DC blocking capacitors at all, but seems we just keep them
there for ease of mind.  Justin and Aaron have
completely eliminated them from their circuits.

Dan



 > The DC blocking caps in series with the primary are not integral to normal
 > operation. In fact, they have no affect on normal operation, so long as
 > they are well above the resonant capacitor match for the primary (1uF or
so
 > is a typical blocking cap value in a mains powered SSTC).
 >
 > They are there in the event that the bridge stops switching, and power is
 > applied to the primary coil for an extended period of time. Without the
 > blocking caps, the primary would appear as a short, resulting in the
 > potential death of your switching devices.
 >
 >
 > Dan Strother
 >
 >
 >
 > >Original poster: "chris swinson" <exxos-at-cps-games.co.uk>
 > >
 > >Hi all SSTC ppl!
 > >
 > >am I right in thinking the DC blocking caps are only there so the coil
 > >will only draw power at Fres ? I wonder what would happen if I took them
 > >out and drove the coils direct. I imagine as long as the frequency is
near
 > >Fres then it wont draw any more power and short out the outstage,
comments ?
 > >
 > >Cheers,
 > >Chris
 >