Re: [TCML] charging reactors

[Finn Hammer <f-h@xxxx>]

jimlux skrev:
> Finn Hammer wrote:
> > Jim,
> >
> > My recent Twin
> > http://www.palaisdetokyo.com/fo3/low/programme/index.php?page=nav.inc.php&id_eve=2503&session=39 
> >
> >
> > was "choked" by a single reactor, but it was a SS job where the 2 
> > coils fired in sync (within 20nS i might add)
> > But although your cluster of coils are non sync, they might fare 
> > surprisingly well the same way, just design for a breakrate that is 
> > [coil breakrate] x [coils].
> > One de"Q"ing diode per coil.
> >
> > Cheers, Finn Hammer
> Interesting.. basically a single choke, and then separate diodes to 
> each primary ...
>
> Depending on how it works out, it might not actually be resonant 
> charging, BUT, the choke would prevent a power arc from the PS.
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In some cases, you might get *more* than resonant charging.

The usual assumption, that the capacitor ends up with double buss 
voltage does not always hold truth in a tesla tank ciccuit.

When the energy stored in the reactor during the time that it takes to 
charge the cap ends up in the capacitor, the voltage on the cap is doubled.

But in a tesla tank circuit, this charging time is preceded by a period 
where the spark gap or IGBT switch is shorted across the reactor. This 
is the ring down period.
The energy stored in the reactor during ring down gets added to the 
energy stored during cap. charge, so that the final voltage across the 
cap becomes higher than Vbuss.
In my experiments with the T-BRISG, I noticed, that when the ringdown 
was allowed to take 600µS, the voltage across the tank cap became 2.3 
times the buss voltage.

So in your case, when say 3 coils have quenched right in succession, so 
that the charging reactor has been passing current for 3 times as long 
as expected, you might find the next cap in line to be overvolted.

No big thing with a BRISG, which would crowbar the supply, but it could 
be *very* bad with a conventional coil.
On second thought, crowbaring the supply under the circumstances 
described might not be such a smart thing to do with a BRISG coil 
either......

Cheers, Finn Hammer

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