Limit start current of high power motor
You have the freewheel diode in the wrong place (or at least as greybeard points out in comments, you don't have a diode in the right place). One should be connected right at the IGBT and power supply, even if there's another one at the motor. The inductance of those leads to the motor could be significant. You want to protect the IGBT against current changing in the sum of the motor and lead inductance. The snubber is designed to protect the IGBT against current changes in only the incidental and unavoidable lengths of wire around it, that's why the capacitor is so small.
Note that the motor, and the leads to it, will maintain a more or less steady current, due to their inductance. When the IGBT is on, current flows through PSU, IGBT and their connecting wires into the long motor leads. When the IGBT is off, current flows through the freewheel diode into the long motor leads. It's the inductive voltage generated by the changing current in the PSU - IGBT- freewheelDiode - PSU loop that will damage your IGBT. First make this loop as small, or at least as low inductance, as possible. Second, put the snubber right on the IGBT to mop up the remaining voltage spike generated by this loop.