SSgap 4-4 Going Well!!

["Tesla list" <tesla-at-pupman-dot-com>]

Original poster: "Terry Fritz" <twftesla-at-uswest-dot-net>

Hi All,

One picture says it all :-))

http://hot-streamer-dot-com/temp/Power.jpg

700 volts and 180 amps (126,000 VA) fully controlled and switched by one
IGBT!  This simply means I have the single IGBT system now working fine!
Note the high loss at this frequency.  The IGBT is cold so the poor little
MMC is probably getting a workout ;-)  I have run at 1100 volts and over
200 amps but my MMC is not quite tuned right to do this at the same time.
The IGBT seems to love current and the voltage is fine too with the
exception of some glitching.  It does not seem to blow anything up however.
 The waveforms are very clean without any signs of trouble.  I am using a
Pearson 10:1 current monitor and a Tek P6015 high voltage probe going to
the Tek3012 scope to make the measurments.  It take a lot of toys to do
this stuff ;-))

I let the scope do VxI and you can see there is some power in the thing ;-)
 This is subject to a lot of error.  The initial turn on is wasting some
power but the IGBT stays nice and cool at the 120BPS I was running for a
few minutes.  Note there is no obvious place for energy to go in this case
since I am just directly shorting the cap with the IGBT!  Note also that
there is no initial spike at all.  This should be vastly quieter from an
EMI/RFI stand point as we thought.  As the frequency goes down, the loss
decreases dramatically but I am limited buy the tuning physics for this test.

I now have 51 ohms in the gate drive.  I tweaked that a lot.  I did confirm
that not having any resistor in there will blow the IGBT :-p  I get a
little loss of the IR2118 control now and then but that is probably do to
the protoboard and flying wires that need to be cleaned up.  I also need to
check the data Marco sent me to see if I am doing something obviously wrong
to cause it.  The thing seems very robust and seems to be happy running
like this.  The waveforms are still very clean and controlled even at this
high frequency.  I tested the over voltage protection and it "seems" to
work.  More testing is needed there...

So tonight was a pretty important milestone.  I now need to start thinking
about building up a full prototype module and the details of how a full
blown system will go together...

BTW - SSgaps will make noise.  Sort of a subtile but low level snappy hum
as the current pulses go through the wires.  Much like corona noise but
still very quiet.

Cheers,

	Terry