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Re: Terry's DRSSTC About finished ;-)

Original poster: Liviu Vasiliu <teslina@xxxxxxxxx>

Thats a piece of "coiling" art Terry!!
Good luck with the first light!

--- Tesla list <tesla@xxxxxxxxxx> wrote:

> Original poster: Terry Fritz
> <teslalist@xxxxxxxxxxxxxxxxxxxxxxx>
> Hi All,
> I ran my DRSSTC into a primary coil and cap (but
> just battery power):
> http://drsstc.com/~terrell/pictures/PowerTest.JPG
> The six 9V batteries easily pumped 10 amps at about
> 60kHz into the
> primary.  The unloaded primary's LC resistance is
> 100 ohms so 10 amps
> represents 1000V.  It could have gone much higher
> but I did not have
> anything insulated or set up to push any real
> voltages.  The over current
> works fine even way down at 10 amps.
> Sort of an interesting picture.  The first downward
> pulse on the yellow
> trace (output voltage) is the startup circuit pulse.
>  Then the digital CT
> has enough signal to drive it onward.  For the first
> 80uS, it is driving
> current into the primary.  Then it is switched off
> By the fiber optic
> remote controller and the energy in the primary LC
> is sucked back up into
> the box.  Note the voltage phase shift in the
> middle.  That surprised me at
> first, but I guess it knows what it is doing ;-)
> The first 5 voltage
> pulses are driven from the IGBTs while the trailing
> 4 pulses are the
> reverse diodes in the IGBTs feeding the primary LC
> voltage back into the
> buss rails.
> The gate drive signals are fast and solid with rise
> and fall times at about
> 100 - 150 nS (these are at the IGBT gates under
> power).  There is some high
> speed glitching.  Hard to tell if that is from the
> differential probe just
> picking up noise or if it is really there.  I will
> order up a load of
> ferrites from DigiKey just in case.  I did clean up
> some gate drive wiring
> which should help too.  The gate drive cards have no
> problem at all driving
> the gates.
> So I put it all together and powered it up!!
> http://drsstc.com/~terrell/pictures/FullyPowered.JPG
> Nothing was connected and no drive signal but at
> this point the buss is
> fully loaded for bear and the IGBTs are fully
> charged and the logic is in
> full control.  If anything were wrong, it would have
> blown up here.  I put
> the cover on the contain any flying burning
> fragments, but all went fine ;-)
> The only real change was to make the charging
> resistor 50 ohms and fuse
> it.  The 100mA of current needed by the gate drive
> cards loaded down the
> 250 ohm resistor and it could only charge the buss
> to 240V.  The 50 ohm
> resistor charges to 305 so no problem when the
> bypass is thrown in
> "snapping" the buss voltage to the full 340 VDC.
> I still have not put the remote control board in
> it's box so I still need
> to do that.  I will also look more into the gate
> glitches.  I think I will
> set the IGBT temperature limit at 50C and the
> current trip at 50 amps for
> starters.  The fan is sort of blocked right now, but
> if it does not need
> more flow I will just leave it as is.  It "seems"
> like it will be fine.  I
> think I can just run my big coil as is with it to
> start but probably just
> run the primary with a big resistor in series at
> first.
> I took a bunch of pictures inside on out:
> http://drsstc.com/~terrell/pictures/F-Front.JPG
> http://drsstc.com/~terrell/pictures/F-Back.JPG
> http://drsstc.com/~terrell/pictures/F-LeftInside.JPG
> http://drsstc.com/~terrell/pictures/F-BackInside.JPG
> Cheers,
> 	Terry