Re: Magnetizing current in SSTCs, my previous posting

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

Original poster: "K. C. Herrick by way of Terry Fritz <teslalist-at-qwest-dot-net>" <kchdlh-at-juno-dot-com>

Right...and now I send a new schematic to Terry,
http://hot-streamer-dot-com/temp/2-t-sim.pdf.  It features a 2:500 ratio (2
primary turns) and 4 drivers coupling via 4 capacitors.  Terry...that's
essentially your OLTC scheme, right?  Except I don't recall if you
resonated the primary.

Here, I've added another 10 m-ohms in series with the (perfect)
transformer.  That cost me 40 KV of output.  Every m-ohm counts in this
primary, as Terry has noted before.

I note the happy result that if I set R1's resistance to 1 meg,
simulating a failure of a driver, the other currents diminish to 290 A
rms.  The same happens when I replace V1 with a short.

Each driver must provide 420 A rms--quite do-able, I gather, using
inexpensive IGBTs.

It now occurs to me that the electronics that drives V1-V4 can have as
its input the signal from the bottom of the secondary.  Using my scheme
for that, noise in the system will start oscillations going, at the
secondary's Fr, even when the primary is somewhat mis-tuned.  Then the
final tuning can be accomplished merely by switching in or out additional
capacitors across C1, C4, C5 and C6.

Someone get onto the hardware!  Jimmy...?

Ken Herrick

On Wed, 14 May 2003 23:44:44 -0600 "Tesla list" <tesla-at-pupman-dot-com>
writes:
 > Original poster: "jimmy hynes by way of Terry Fritz
 > <teslalist-at-qwest-dot-net>" <chunkyboy86-at-yahoo-dot-com>
 >
 > Hi Ken,
 >
 > You mean that the primary inductor and capacitor resonate at the
 > same freq.
 > as the secondary, and you are driving it at resonance with a square
 > wave
 > right? it sounds kind of like my DRSSTC, I like the idea alot!
 > ;-))
 >
 > I will write some more tomarrow, but it is bedtime now :-)
 >
 > Tesla list <tesla-at-pupman-dot-com> wrote:
 > Original poster: "K. C. Herrick by way of Terry Fritz "
 >
 > In http://hot-streamer-dot-com/temp/1-t-pri.pdf, which I just sent along
 > to
 > Terry, I've now upped the simulated primary to 2 turns instead of
 > one (by
 > changing the ratio to 0.004 instead of 0.002) and changed C1 to 1.7
 > uF to
 > keep the primary Fr the same, and R1 to 20 m-ohms for the two turns.
 > I
 > now get 250 KV at the output instead of 350 but the input current
 > goes
 > down to 1.6 KA rms--a big improvement over 5.1!
 >
 > Unconventionally using the transformer the way I do, the secondary
 > inductance is held the same by the program; by changing the ratio,
 > I
 > simulate a change only in the primary inductance and hence in its
 > number
 > of turns. Starting with fixed secondary inductance and assumed
 > (fixed)
 > real turns of 500, I figure that a change in the simulation-ratio
 > will
 > d! irectly simulate a change in the real ratio.
 >
 > With a simulated 3-turn primary , 750 nF for C1 and 30 m-ohms for
 > R1, I
 > get only 175 KV out but just (just!) 750 A rms in.
 >
 > It would seem as if a 2 turn primary would be a good compromise.
 > How
 > does this jibe with others' findings? And does anyone agree or
 > disagree
 > with my use of the transformer?
 >
 > Ken Herrick