SISG IGBT power loss calculations

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: Vardan <vardan01@xxxxxxxxxxxxxxxxxxxxxxx>

Hi All,

I have been matching figures 10 and 11 in the SISG pdf:

http://drsstc.com/~sisg/SISG.pdf

to models.  It appears that the very low resistance allows the 
inductance of the SISG gap to become significant and thus is why 
voltage and current are out of phase.  It is neat because that gives 
the resistance a poorer power factor which makes it run cooler :-))

The gap appears to be a 0.020 ohm resistor in series with a 20nH 
inductor.  So for power calculations, each gap section dissipates the 
primary loop RMS current squared multiplied by 0.020 ohms.

http://drsstc.com/~sisg/SISG-Model-01.gif

http://drsstc.com/~sisg/SISG-Model-02.gif

http://drsstc.com/~sisg/SIDAC-IGBT-3.sch

For my 183 watt test, the RMS primary current is 11 amps, so the 
power in the five sections is 12 watts total.

Thus, the gap is loosing about 6.6% of the total coil energy.  The 
only other major loss would be in my big secondary made from #28 wire 
that probably dissipates 8 watts as heat.  So with 183 watts in, 
about 163 watts is making it to the streamer for an efficiency of 
89%.  That would actually place an upper limit on the Freau value of 
2.35.  To get there (or real close) one needs to reduce the RMS 
current and make the secondary reasonably low loss.  Lots of 
tradeoffs to juggle there...

Cheers,

	Terry