Is there any fuse that could blow in 10-40us at a current of about 1500Amps? The normal operation current would be about 500Amps, but short (2-3 us long), with a repetition rate of around 400 Hz. I'm looking for a fuse that would have a defined behavior for such a situation.
Sure! I can get you one for, [counts on fingers and thumbs, thinks for a moment], about $2000 at quantity 10, lead time 20 weeks.
Also, what kind of fault should I suspect when an IGBT got stuck open for an extended period of time?
Open? So Vge <= 0V? That'd be a victim of overvoltage. IGBTs aren't rated for avalanche, and avalanching a transistor isn't healthy, at the best of times, anyway.
Or maybe excessive dV/dt.
This led to its destruction and is currently completely shorted out. Is there any way an IGBT might get stuck in one state?
Shorting it out certainly gets it stuck in one state...
The gate driver seems OK and I do not think it gave it a longer pulse.
Mind that when an IGBT fails, it typically fails as a three-way short. The gate driver probably got blasted with a few hundred volts, current limited by the gate resistance. It may be okay, or it may malfunction (e.g., bad rise or fall time, excessive heat dissipation, temperature sensitivity), or it may be completely toast.
No such thing as a fuse that will blow in 20-40us at just 3x rated current; perhaps at around 100x rated current you'll find fuses are fast enough.
The fastest (conventional passive) fuses in the world are "semiconductor fuses", so called because they can manage to protect
some semiconductors,
sometimes. In practice, the only semiconductors robust enough to survive are diodes and SCRs (and I suppose IGCTs), and they really should be considered "suspect" after sinking fault current.
Semiconductor fuses are often used with IGBTs, but not for electrical purposes: the quick breaking action (within a few hundred microseconds -- ten times longer than it takes for the IGBT die to begin turning into magic smoke) minimizes arc flash and shrapnel.
Tim