Re: Wild Idea OLTC - Split core inductors

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

Original poster: "Wall Richard Wayne by way of Terry Fritz <twftesla-at-qwest-dot-net>" <rwall-at-ix-dot-netcom-dot-com>

8/17/02

Terry,

If you want higher peak voltage just use a voltage doubler and eliminate
the inductors.  It will only take a few additional diodes.  Nothing is for
free though.  There will be additional power required from the bridge. 
But, Hey! More power through put to the coil -- that's a good thing. I'll
try to draw a schematic, scan it and send a jpg file to you.  There are
innumerable voltage multiplier schemes and I'm sure everyone has their
favorites.

http://hot-streamer-dot-com/temp/ON-LINEVoltageDoubler.jpg

As for the timer pulse -- move the CT up to where it senses current just
past the bridge.  Then you are more free to choose Cf capacitance.  For
simplicity, I understand why you still tie switch firing to the mains AC
frequency.  This does create overall severe coil performance problems as
does having the switch in series in the primary LC tank which destroys
synergy between the primary and secondary coil.  Future generation low
voltage coils will, no doubt, require good DC voltage filtering if not DC
voltage regulation and complete control of switch firing disassociated from
the mains frequency.  Also, by necessity the switch will be outside the
primary LC tank.  This will permit synergy and resonance will reign.


> >Why are these large inductors here in the first place?  What do they do? 
> The inductors are resonant with the 47uF primary cap at 60 Hz.  That
drives
> the 340 peak AC voltage to about 550 volts (could be more with timing
tricks).
> 
> 1 / (2 x pi x SQRT (0.15H x 47uF)  = 60 Hz.
> 
> >They do form an LC filter on each side with Cf1 (1uF) and Cf2.  Are they
> >just for smoothing DC?  If so, just make CLC pi filters on both sides. 
Put
> >Cf3 and Cf4 (like above) below the inductors on both sides.  This would
> >allow much, much smaller inductors.  You could use 600 VAC motor run caps
> >for the Cf caps.  You could use much higher cap values than 1 uF.  Run a
> >spice model to choose size of capacitors and inductors for CLC pi
filters. 
> >Price should be very inexpensive.  
> 
> The values of Cf are chosen to provide a nice low side "spike" to trigger
> the IGBT's.  They also absorb high voltage kickbacks off the inductor.

RWW


--- Richard Wayne Wall
--- rwall-at-ix-dot-netcom-dot-com