I recently bought an IXXH80N65B4 high voltage/current IGBT. I had it wired according to the circuit below, which is part of a coil gun. Coil Gun Circuit

After successfully firing the gun twice, I used the same IGBT in the below circuit, in preparation for the addition of a microcontroller. The datasheet of the IC can be found here. Driver Circuit

After powering up this circuit, the IGBT seemed to latch on. Nothing I could do would make it turn off, even shorting gate and emitter. If I supplied voltage to the gate, it seemed to short gate and emitter. Is this IGBT done for, or is there some way to fix it? Also, what can I do to prevent this from happening in the future?

  • \$\begingroup\$ Did you verify proper pulse output of microcontroller before testing with IGBT? How long do you turn on the transistor? How long is transistor off? Does transistor have heatsink? \$\endgroup\$ – Marla Jan 12 at 3:43
  • \$\begingroup\$ I didn't use a microcontroller yet. I setp up the circuit on a breadboard according to the schematic, and noticed the LED was on. The IGBT didn't have a heatsink, but I never noticed it get anywhere close to warm. \$\endgroup\$ – Aleksandr Spackman Jan 12 at 4:31
  • \$\begingroup\$ be very careful with layout and dI/dt and use 80A diodes in reverse across coil. \$\endgroup\$ – Tony Stewart Sunnyskyguy EE75 Jan 12 at 6:35

Turn power off (and if the IGBT is not soldered in, remove it), and measure resistances between gate, emitter and collector (or use the meter's diode function, if it shows a short as zero). Measure each pair in both directions. If the emitter-collector pair shows short (0 ohms or 0 volts) in both directions, you have blown the IGBT. If the gate-emitter and/or gate-collector also shows short in both directions, you've really blown the IGBT. Even in-circuit it shouldn't show short in every direction, so that's a pretty good indication that it's fried.

  • \$\begingroup\$ According to my multimeter, every metal contact of the IGBT is shorted haha. I guess it's pretty blown. I don't understand, though. The ratings on the IGBT are well above the voltages and currents used, and the beefy flyback diode would protect from reverse polarity, correct? \$\endgroup\$ – Aleksandr Spackman Jan 12 at 4:21
  • \$\begingroup\$ Uh oh. Looks like I misread the datasheet on my diode. It's completely blown, and it now conducts both ways. Even so, shouldn't it technically protect the IGBT from reverse polarity, even if it ruins other parts of the circuit? \$\endgroup\$ – Aleksandr Spackman Jan 12 at 4:29

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