Re: IGBT Brick hits 1200A

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

Original poster: "Terry Fritz" <teslalist-at-qwest-dot-net>

Hi,

I ran into a problem where the currents say (5000 amps!) and the low loop 
resistance ~0.1 ohms was just too much for snubber style circuits.  I just 
had to let it go.  But my OLTC did not seem to mind.

However, I am no genius when it comes to snubber circuits so maybe others 
can figure it out.

A MicroSim model of my OLTC is at:

http://hot-streamer-dot-com/TeslaCoils/Programs/MicroSim/MicroSim.html

I think you have to redefine the Bv on the front end diode models to 1000 
volts instead of 100 volts.

Cheers,

         Terry


At 03:20 PM 5/18/2003 -0400, you wrote:
>Sounds like you need a simple snubber (resistor-capacitor) across the diode
>to supress the ringing.
>I have some detailed MathCad/Pspice calculators / simulations for precise
>snubber design if you are interested.
>Contact me offline.
>
>The Captain
>
>
> > >The ringing appears to be caused by the fact that the IGBT
> > >is trying to turn off during the haversine when the IGBT elements
> > >are conducting current.  I would think that turning the IGBT off
> > >about 2uS earlier [during the diode haversine] would accomplish
> > >smoother commutation.
> >
> > As far as I can tell, it _is_ being turned off during the diode conduction
> > period. The ringing is just the diode recovery transient.
> >
> > I'll recheck that, but I think if I _had_ been turning it off while the
> > IGBT was passing current, with no snubber, I would have blown something.
> >
> > Steve C.
> >
> >
> >
> >
> >
> >
> >