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Re: [TCML] DRSSTC ring-up

2013/5/28 Steve Ward <steve.ward@xxxxxxxxx>

> >  From simulation it seems, that a coil which does simple primary zero
> > current switching,
> >
> > will ramp up with a mixture of both poles, if primary and secondary are
> > tuned close.
> > This will show up as a beating, i.e. an oscillation of the current
> > amplitude.
> > If there is a considerable difference in primary and secondary resonant
> > frequencies,
> > the coil will ramp up mostly with the pole, which is close to the primary
> > freq.
> > That leads to less beating.
> >
> > Sadly, this is just the "wrong" pole in the light of the above. So some
> > special
> > electronics is needed to achieve the nice effects Steve described.
> >
> >
> I hope to some day release my newer driver design for sale, but i think its
> sufficiently complex that it would be sold as a completed unit to avoid too
> many assembly issues.  More on that when its closer to being releasable.
This is a text that I wrote earlier this year about drsstc tuning, poles,
I design the system assuming no losses, aiming for complete energy transfer
after a given number of cycles, leaving no energy in the system except in
the output capacitance, the same idea of the conventional Tesla coil. The
design is then unique. This results in the primary tuned slightly below the
secondary. The text shows that the best tuning for efficiency is between
the poles, and that a design is always possible for a given maximum input
current. Zero-current switching comes naturally with the design. There is a
problem with this tuning if a PLL is used, because the PLL may become
unstable (I don't see much sense anyway in using a PLL with just a few
cycles to lock). A simple comparator controlled by the input current (maybe
after some filtering, but the primary circuit is a filter already)
apparently works correctly in simulations. I have tried the design
experimentally only with a fixed frequency driver. It works correctly too,
but I didn't try the effect of long streamers that would significantly
detune the system.

Antonio Carlos M. de Queiroz
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