short circuit protection of IGBT?

[coppercone2]

do you just put a rogawski coil right before the h-bridge and trigger a SCR with it?

there are hocky puck scr that look like they can work.

what would you use as a current limiter? do they have little carbon pucks or something?

would a mov be a better choice off the shelf? it has some resistance.

[coppercone2]

i cant find it free

Not my stuff, as its way too academic for this noob hobbyst , a sneak peek. 

that graph actually makes me want to buy it

[coppercone2]

i used those chips before but it cant hurt to have secondary protection

the iso5500 has it built in

i think it would be cool to experiment with the scr. and it seems a project that could justify from a cheaper inaccurate pcb rogawski coil

[T3sl4co1l]

I wouldn't put a crowbar on there.  The fault currents available from large capacitors (film or electrolytic, as they happen to be) plus the mains (if we're talking industrial 480 here) is ridiculous.  You'll spend as much on the crowbar as the inverter.

Parts are dying either way.  Replacing a fuse plus SCR plus IGBTs isn't any better than replacing just the fuse and IGBTs.

Better to prevent failure from happening in the first place.  Monitor operating conditions, use redundant power stages or switches (series connected..?) if necessary, respond to faults quickly.

That's good enough for industry.  Heh.  Well, maybe I shouldn't reference industry here, the old designs I saw were discrete logic and no inverter protection whatsoever...

You may find it more interesting to look up what they do for managing power on board the ISS.  It's a public project, freely accessible (if a bit hard to find your way into the design resources).  Many kW of solar power, distributed safely through vacuum as well as interior spaces.

Tim

[Zero999]

I do not remember where now but I saw IGBT short circuit protection implemented using a low voltage high current power MOSFET in series with the emitter of the IGBT.  Under normal conditions, the IGBT gate controlled switching but under fault conditions, the gate of the power MOSFET was clamped low very quickly disconnecting the emitter of the IGBT and driving the gate voltage of the IGBT negative.

That's a good idea. The MOSFET can also double as a current sense resistor.

[coppercone2]

the ISS uses shunt regulation it seems.