RE: DRSSTC - I think I heard Cross Conduction...

["Tesla list" <tesla@xxxxxxxxxx>]

Original poster: "Steve Conner" <steve.conner@xxxxxxxxxxx>

>I am beefing up the traces, but I don't think anything could stop it once
>it lets go. But the breakers and fuses did not trip so the IGBTs blew
>themselves out of the circuit very quickly.

Hi Terry, Sue, all,


Yes I agree, transistor destruction is just a fact of life. There is no
practical way to protect them with fuses or breakers, the best you can hope
for is that a fast blow fuse would stop the transistor case from actually
rupturing once it had shorted. But a fuse in the DC supply line would add
more resistance and inductance which are Bad Things. The usual procedure
seems to be just let them rupture and build the rest of the wiring chunky
enough to survive an "event".

PS- I second Bob's comment about the loop area of power connections. You can
get all sorts of unwanted ringing this way. If you minimise the loop area
everything should run cooler and more efficiently. I like to use laminated
copper sheets for the DC bus.


>When I build the bigger H bridge, I have to look into why I can't use as
>much top loading as Steve W. uses. I have enough extra turns available to
>get it in tune, but I get smaller sparks, and it draws much more current

That's interesting. What frequency, tank capacitor, DC bus voltage, pulse
width, etc, are you using? I'll try putting it into my simulation program
and see what it says. My gut feeling is that you aren't delivering enough
power to pump the larger topload up to a decent voltage.


Steve C.