Re: PLL SSTC

["Tesla list" <tesla@xxxxxxxxxx>]

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

I made up my own version of the 4046 SSTC controller.  Its not DRSSTC
worthy in my opinion (though you could make it so), but i used it for
my highest power SSTC (running well over 5kW).  Schematic and pics
here:

http://www.stevehv.4hv.org/CWcoil/

As mentioned, PLLs can be finicky if you dont use the right filtering
on the VCOinput.  You also have to be careful of setting the upper and
lower frequency limits.  Also, in my case i used secondary current
feedback, and i found a problem with ground arcs that are too short.
It seemed to cause the circuit to lose lock, and id have to reset the
PLL.  This problem seemed to have spawned as my PLL circuit became
better at maintaining the proper phase shift... so making it better in
one respect seemed to weaken it in another.  When the PLL "messes up"
nothing is damaged as the primary current is very low when off
resonance, so it just stops sparking and i cut the bridge power and
then restart.  Its not really a problem if you are careful about
ground targets.

Steve Ward

On 9/5/06, Tesla list <tesla@xxxxxxxxxx> wrote:
> Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>
>
> Hi,
>
> I think Steve Conner has done the most with PLL solid state Tesla coil stuff:
>
> http://scopeboy.com/tesla/index.html
>
> http://scopeboy.com/tesla/dwsstc/wk2.html
>
> The problem is Tesla coil waveforms like this:
>
> http://hot-streamer.com/temp/NightmareWave.gif
>
> Fricking had for a PLL to track!!  But Steve has been the most
> successful!  I think he has better stuff now...
>
> Most other designs use "fast" zero crossing detectors on the primary
> current to do it all in real time:
>
> http://drsstc.com/~terrell/schematics/MainController-1.0.pdf
>
> http://drsstc.com/~terrell/schematics/CurrentMeasurement.gif
>
> http://drsstc.com/~terrell/schematics/OpticalGateDrive-1.0.pdf'
>
> http://drsstc.com/~terrell/schematics/H-Bridge-1.0.pdf
>
> Connor, Ward, and certainly Dan do better then "me" here ;-))
>
> http://scopeboy.com/tesla/
>
> http://www.stevehv.4hv.org/SSTCindex.htm
>
> http://www.easternvoltageresearch.com/
>
> The "real thing" would be to have a uP hard number crunch it all in
> real time...  I have "imagined" doing it with this:
>
> http://www.parallax.com/dl/docs/prod/prop/PchipBlockRev.pdf
>
> But just "pie in the sky" ;-))
>
> I got some 4046's once but never used them since the fast real time
> stuff was better for me.
>
> Cheers,
>
>          Terry
>
>
> At 10:22 PM 9/4/2006, you wrote:
> >Dear forum members,
> >
> >I believe few members of this forum have used a PLL (4046) to
> >'auto-tune' the SSTC. I'm trying to build a similar system. I
> >believe due to noise and (or other reasons?), the PLL would go
> >out-of-tune and this may (or may not?) result in HARD switching of
> >IGBTs/MOSFETs in the switching circuits or sometimes may result in
> >huge currents drawn from the switching circuit. So, is there a way
> >to find out if the PLL is 'in tune' or not? Has anyone used the
> >'Phase Comparator Pulse Output' (Pin #1) in CD4046BC? Please help.
> >
> >Thanks and regards,
> >Rajesh.
> >