Hi! I have a semikron skiip 12nab126v20 module which has high power igbt in it and I wanted to test them with LED in circuit, but the normal circuit test isn't actually working, and I have to give it a reverse voltage to turn it off. Does anyone know how should I change the circuit?

 

First off, where's the Circuit ?
This sounds like You are letting that Gate-Pin flop-around in the breeze.
You may have already damaged the Gate and ruined the part
by leaving the Gate in a "Floating" condition.
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.
.

 

First off, where's the Circuit ?
This sounds like You are letting that Gate-Pin flop-around in the breeze.
You may have already damaged the Gate and ruined the part
by leaving the Gate in a "Floating" condition.
.
.
.

this is the circuit .
you know, someone told me that because this is power igbt and when you stop exciting the gate it has a very small current and because of the high power , the current is enough to turn a small LED on. and here is its characteristic

 

That Circuit won't really prove much at all,
other than the IGBT is probably not smoked and shorted.
High-Impedance Inputs don't last long rattling around in a junk-drawer,
the Input can be "partially-damaged" by mis-handling.
.
.
.