Circuit Analysis: DRSSTC
From: the Tesla List
Date: Tue, 20 Jun 2006 11:46:28 -0600 - Subject: Circuit Analysis: DRSSTC
Original poster: Greg Leyh
Hi All,
Is there a primary circuit schematic and waveform set that defines the
quintessential DRSSTC? Searches of pupman archives seem to hint at resonant
primary switching, with relatively long (>>6 cycles) dwell times -- similar in
nature to a resonant-mode converter. I had originally thought that the DRSSTC
uses a full-wave bridge, in a hard switch-mode approach (square primary voltage
waves, ramped primary current waves, sinusoidal secondary V&I waves.)
I'm currently running a batch of simulations in Simplorer, and wanted to further
characterize the relative efficiencies and drawbacks of various primary
switching topologies.
Best Regards, Greg
Date: Tue, 20 Jun 2006 18:18:52 -0600 - Subject: Re: Circuit Analysis: DRSSTC
Original
poster: acmq
I did some research about the behavior of DRSSTCs some time ago. The results,
along with a design and simulation program, are in: http://www.coe.ufrj.br/~acmq/tesla/sstc.html
My main objective was to make the DRSSTC configuration produce waveforms similar
to the ones in a classical Tesla coil, charging the secondary capacitance with
maximum efficiency, supposing that the energy stored
there would be the main source of energy for sparks (or any other use). The
theory about how to do this in lossless conditions is complete. See here:
http://www.coe.ufrj.br/~acmq/tesla/drsstc.html.
The design program also implements this design.
- Antonio Carlos M. de Queiroz
Date: Tue, 20 Jun 2006 20:38:02 -0600 - Subject: Re: Circuit Analysis: DRSSTC
Original poster: Vardan vardan01
Hi Greg,
At 09:37 AM 6/20/2006, you wrote:
>Hi All,
>
>Is their a primary circuit schematic and waveform
set that defines the quintessential DRSSTC?
Almost "any coil" with the "drive" as a say +- 300V square wave synced to drive
the primary current...
>Searches of pupman archives seem to hint at
resonant primary
>switching, with relatively long (>>6 cycles)
dwell times -- similar
>in nature to a resonant-mode converter.
DRSSTCs can "drive" as "long as they want" until a current limiter is reached or
the silicon spills all over the ceiling :o)))
>I had originally thought that the DRSSTC uses a
full-wave bridge, in
>a hard switch-mode approach (square primary
voltage waves, ramped
>primary current waves, sinusoidal secondary V&I
waves.)
There are half bridges too... Dan's DRSSTC III is a half bridge drive... But
they are all "hard driving" given their specific rail voltages...
>I'm currently running a batch of simulations in
Simplorer
>(Ansoft...), and wanted to further characterize
the relative
>efficiencies and drawbacks of various primary
switching topologies.
You just "drive it" ;-))) Being able to do drive the switch over at the "zero
current crossing" is a big deal. Most circuits do the crossover significantly
"late". The propagation delay between the current transducer saying "go" and
the IGBTs actually "doing it"... Usually not a giant problem at all..
If you are doing "batches".... ScanTesla is probably "all done with it" by now
;-)))
http://drsstc.com/~sisg/files/scantesla/scantesla762.zip
A "secret" later version with advance streamer modeling. But the streamer
constants are still in "flux":
http://drsstc.com/~sisg/files/SISG-coil/ScanTesla763/scantesla763.exe
http://drsstc.com/~sisg/files/SISG-coil/ScanTesla763/scantesla763.c
But "bleeding" edge there...Cheers, Terry
>Best Regards, Greg
Date: Wed, 21 Jun 2006 20:50:21 -0600 - Subject: Re: Circuit Analysis: DRSSTC
Original
poster: acmq
> Original poster: Greg Leyh
>
> Hi Antonio,
>
> Great work. I now understand from your program
that the DRSSTC
> *does* operate as a resonant-mode converter;
the primary current is
> mostly sinusoidal, and there is a resonant cap
in series with the
> primary. For some reason, I had originally
thought that the DRSSTC
> IGBT switches hard-switched directly into the
primary, from an
> arbitrarily large capacitor bank.
But the switches really switch a DC voltage over the L1-C1 series association.
The DR is for double resonance. The circuit has two resonances because of the
primary capacitor.
> One question: does your solver for the 'Lossy
Design' have a way to
> calculate the total energy lost to primary
circuit resistance during
the initial ring-up?
No. The model implemented on the dedicated simulator in the program does not
have resistance in the primary. I will see if I can add and calculate losses.
There is a program TRSSTC in
http://www.coe.ufrj.br/~acmq/programs
that solves the magnifier version of the DRSSTC, and the simulator there has
losses implemented. It does not calculate the lost energy, but you can see its
effect in the plots.
Antonio Carlos M. de Queiroz
This discussion surely continues. Go to www.pupman.com and check the June 2006 archives
- 5-22-11