RE: OL-DRSSTC 7 - It's Alive!

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Jason Judd" <JJudd@xxxxxxxxxxxxxxxx>


Hi Terry, thanks for sharing your latest work.

Do you think the gate switch glitches will become a problem at higher
power levels ? I was seeing the same thing when I was trying to run my
DRSSTC with primary feedback. At higher power levels the glitches seemed
to be turning the IGBTs back off for about 100ns. The coil worked fine
up to about 2' sparks, but then the IGBTs started to fail. I had thought
the glitches were the problem, but it now seems that late switching was
making the IGBTs swich at more than their 205amp (IRG4PG50WD) rating and
causing latch up.

Jason.

>
> Yellow is primary current and blue is a gate voltage.
> Between 15 and 16uS you can see the dead time glitches.
>
> http://hot-streamer.com/temp/OL-DRSSTC-2005-10-09-GateDrive1.gif
>
> timing seems pretty late, but the peak current is low so the
> gate drive is low and slow too:
>
> http://hot-streamer.com/temp/OL-DRSSTC-2005-10-09-GateDrive2.gif
>
> http://hot-streamer.com/temp/OL-DRSSTC-2005-10-09-GateDrive3.gif
>
> http://hot-streamer.com/temp/OL-DRSSTC-2005-10-09-GateDrive4.gif
>
> In general, it seems to work fine!  Some technology certainly
> need to be worked out, but there is no fundamental problem at
> all...  And, it makes foot+ sparks "easily" even the "first time" ;-))
>
> Cheers,
>
> 	Terry
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