It destroys by
* overcurrent
* overvoltage
* overheat / power dissipation
A scope will show you.
measure the DS voltage .. with the two scope clamps directely at the IGBT pins.
* Focus on the voltage peak when the IGBT switches OFF.
* and focus on the (low) voltage when the IGBT is ON.
I uesed very big heat sinks for IGBT (GT60N321)
and I uesed MUR6060PT as a free-wheeling diode In parallel the dc motor
the circuit worked well , but when I Turned off the circuit
the IGBT (GT60N321) damaged
could you help me why the IGBT damege?
Ok, I see. This is not wrong. You try to avoid overvoltage at the expected source of energy.
On the other hand...
If there are other possible sources of high voltage peaks(stray inductance of wiring, overshot in DC bus) ...you need several protection circuits.
A single) fast overvoltage protection close at the IGBT will protect the IGBT in any case...with any source of overvoltage...
If you don't want to connect an overvoltage protection circuit across the IGBT...then you need to add a protection device across each possible source of high voktage.
* Motor us simple.
* power supply is simple
* wiring stray inductance is difficult or impossible
* any other source?
And you need to consider that all the added (worst case) voltages need to be lower than the IGBT specification.