Re: OLTC maggy

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

Original poster: "Antonio Carlos M. de Queiroz by way of Terry Fritz <teslalist-at-qwest-dot-net>" <acmq-at-compuland-dot-com.br>

Tesla list wrote:

 > Original poster: "Stephen Conner by way of Terry Fritz 
<teslalist-at-qwest-dot-net>" <steve-at-scopeboy-dot-com>

 > I'm certainly prepared to design one. I've studied Antonio de Queiroz's
 > magnifier design page and it seems as if it might give advantages over the
 > 2-coil OLTC. If I understood correctly, with a 1:2:n system the energy is
 > only in the primary circuit for 1 cycle, which would give better
 > efficiency/power handling than my current OLTC that takes 3 cycles. Of
 > course, fast quenching is no problem with IGBTs. The kickback problem still
 > needs work but I suspect a bit of PSpice simulation might help.

You are right. In the modes 1:2:3, 1:2:5, 1:2:7, etc., the primary
current crosses zero just once before the energy transfer is complete.
The current is zero again when the output voltage is maximum.
"Kickbacks", caused by interruption of the primary current when it is
far from zero, can occur due to detuning, or premature breakout at
the output. It is also important to switch the primary in a way that
effectively opens the primary circuit for current in both directions,
or some energy will be transferred back to the primary while the
secondary oscillates freely, after the interruption of the primary
current.
A problem with these fast modes is that the driver inductance is larger
than the third coil inductance, and the secondary capacitance has to
sustain a large voltage. Maybe possible to use a distributed
capacitance.
What happens in an ideal lossless circuit can be simulated with the
program mrn6 (see also the program magsim), in:
http://www.coe.ufrj.br/~acmq/programs

 > However, I can't be sure whether I would have the time/money/amount of 2000
 > amp IGBT bricks required to actually build my creation.

Maybe better to start with a low-power system (100W - 200 W), to see
if the idea really works.

Antonio Carlos M. de Queiroz