Re: OLTC Maggy modelling

["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 got this slightly wrong. Actually the effective circuit is one IGBT and
 > one diode in series, for about 1.5x the losses of a single IGBT. However
 > you need a separate IGBT and diode to carry the negative half-cycles. The
 > overall losses are roughly 6 times more than if you had just got the two
 > IGBTs and put them in parallel. IGBT bricks wouldn't avoid this problem.

You can use two IGBTs back-to-back, with positive gate drive in one and
negative gate drive in the other. The current would pass through one
device and the reverse diode of the other.

 > Of course you could just allow it to kick back into the primary, and use a
 > different kind of charging circuit that wouldn't be affected.

The primary capacitors would be recharged in any way if current passes
through the IGBTs after the quenching instant. What you can do is to
just allow the energy to be dissipated as it wants in both circuits,
by not interrupting the current. Would this really make a difference?
Almost everything would go to the streamers anyway.

 > It could be
 > argued that good streamer/arc loading would drain most of the power from
 > the resonator before it had a chance to kick back. This is the approach
 > that I would take. In theory.

This would be the case in arcs to ground. In streamers, I don't think
so. But it's easy to experiment and see with this device.

 > In practice I have many other things to do,
 > like finish my PhD thesis, find a job that doesn't suck, replace my cracked
 > bike frame, and hit the trails :)

Oh yes.

Antonio Carlos M. de Queiroz