Exploding IGBT's

[KingKrak]

Hey,
I posted a thread about 2 months ago about a problem that I was having with exploding IGBT's on a circuit I'm trying to make. The general consensus is that the voltage rating on my IGBT's was too low, and hence why they were exploding.

Well, after waiting a month for new higher voltage rated IGBT's to turn up, I am still faced with a similar problem. Kind of...

I now have 1200V IGBT's and I am putting around 600V across them. I have attached 2 circuit diagrams. The circuits don't really do anything, and are just test circuits to see if the IGBT's hold out. As you can see the gates are tied to ground, and so there is no switching.

With the first circuit, when I turn the power on the single IGBT is able to hold out indefinitely. I even left it running for 20 minutes and it had no problems. When I connect up the second circuit and apply the power after about 2 seconds the topside IGBT blew up. Maybe the bottom is damaged too, but it didn't explode.

Looking at the exploded IGBT, the gate pin has been completely blown off. There is also a very thin "tunnel" through the casing between the emitter and collector (I can see this because the casing came off and exposed it). This is pretty consistent with what keeps happening to me.


Everything else on this project is complete, it's just these IGBT's holding me back and it's becoming very very frustrating!!!

 

[ronsimpson]

The circuit with one IGBT should work fine.
The circuit with two IGBTs will pop the top IGBT's gate. Normally the G and E voltage is held with in +/-20 volts. You have the C at 600 volts, the gate at 0 volts and the emitter at ? volts. The emitter is not really connected. It is likely the G-E voltage is unknown and larger than 20 volts.

 

[KingKrak]

Thanks, that was exactly what the problem was. It's funny how sometimes the obvious things aren't obvious when you get so involved with it.

I connected the gate of the top IGBT to it's emitter and no more explosions!