Re: Terry's DRSSTC -"different" H-drive functions...

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Original poster: Steve Ward <steve.ward@xxxxxxxxx>

Hi Antonio,

You said:


> The third situation is if the driver is short-circuited. The system
> from this time on behaves as a regular Tesla coil, when all the energy
> is in the secondary (or split between primary and secondary if the
> driver is short-circuited before complete energy transfer). The two
> tanks are slightly mistuned, but the waveforms show the beats seen
> in the energy transfer of a regular Tesla coil. The problem is that
> in a drsstc with my tuning method the primary capacitor (or the primary
> tank) stores at most about 1/4 of the bang energy during the energy
> transfer. With the driver short-circuited, almost all the energy in
> the secondary system, assuming no breakout, returns to the primary
> circuit, generating capacitor voltages and currents with about twice
> the value that appears in the forward energy transfer with the driver
> in operation.

So im curious if you see any benefit to this situation assuming that
say 3/4 of the bang energy is used up in the streamer, and then the
driver is shut down, but with 2 IGBTs shorting it so to speak.  I have
shown with my tests that breakout is achieved quite early when maximum
power is achieved, so this may be a plausible situation that most all
of the energy is used up anyway, but it couldnt hurt to get all the
energy out of there ;-).

A situation with NO breakout would somewhat also imply that there isnt
much energy in the system anyway, so 2X the voltage and current
flowing afterward, while maybe not useful (or would this energy, now
manifested, be coupled back to the secondary?), probably wouldnt be
that devistating to a well built system... in any case what is the
point of a tesla coil that doesnt make sparks? ;-).

>
> So, my conclusion is that it's best to operate in the second case,
> letting the free-wheeling diodes return to the power supply the
> unused energy.

I would agree there as well, seems like the "safest" way, but one must
be sure to have *minimal* resistance and inductance between the IGBTs
and the DC filter caps.  Its interesting to see the buss voltage raise
noticably from this event, though maybe my scope probe was just
picking up noise...

More to think about.

Steve

>
> Antonio Carlos M. de Queiroz
>
>