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I am trying to use an IGBT module (dual IGBTs in common-emitter arrangement) as a static switch for 120VAC. I've done as much reading as I can, and I understand there are issues with losses and turn-on/off challenges. I am building 3 different switches using different devices and comparing losses, transient response, etc.

Here is my issue. I ended up burning the input (control) side of my gate driver. I think gate current went through it and destroyed it. High current (presumably) went out the VCC1 pin and into the microcontroller, destroying it as well. Everything else seems fine. The DC-DC converter appears unscathed, as does the IGBT and snubber.

I am not great at drawing schematics yet, so apologies for it being slightly messy. I am using a MGJ6 15V/10V DC-DC converter (https://www.mouser.com/datasheet/2/281/kdc_mgj6scdc-1019175.pdf) to power my gate driver, which is a 1EDC60I12AH (https://www.mouser.com/datasheet/2/196/Infineon-1EDCxxI12AH-DataSheet-v02_00-EN-1272149.pdf). 100nF decoupling caps on both modules and a 20μF bulk cap on each DC-DC output. 20R resistors on sink and source driver outputs. 1μF-47R snubber network. I tried following the recommended setup using a bipolar supply for the gate driver the datasheet recommended.

Have I made any foolish mistakes with my schematic or chosen components? Am I not grounding components properly? Is there some underlying isolation issue that isn't clear to me?

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There are plenty of reasons that can cause IGBTs blowing.
Here are just some suspect points regarding IGBTs.
A) Your 2 IGBT connection look suspicious. PS-Collectro-Emitter-Emitter-Collector-Load?
B) Driver output resistors according DS - top one 3 times bigger than bottom one. In your circuit they are both 20R.
C) Wires that goes to Gate should be as short as possible (avoiding parasitic inductance).
D) Parameters of Driver and IGBTs must match each other. Double check things like Driver output voltage and current, IGBT gate charge, threshold voltage, switching frequency.

Most time these kind of circuits require very detail design and step by step debugging with oscilloscope. For your and others better understanding SCH design must be done properly not just draft on paper with pen. Your time learning any free available CAD tolls will definitely worth it considering possible losses.

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  • \$\begingroup\$ A). You are absolutely right. I have made a mistake. Page 7 of the 1EDC60I12AH DS. I have the -5V GND2 connected to the emitter--it's supposed to be the reference GND from the DC-DC converter. I'm inclined to believe this is what did it in. B). Yes, I chose a higher resistance on the sink (turn-off) resistor to increase turn-off time and reduce current. Could you elaborate on why they need to be different? C). They are as short as I could make them (less than 2 in) and also solid. D). Both are Infineon and the driver is designed for this series and 1200V. \$\endgroup\$ – usinjin Apr 4 at 9:07
  • \$\begingroup\$ B) These resistors act as Gate current limiter. 10R in DS affect IGBT "On" slew rate and 3.3R affect "Off" slew rate. By having 20R on both you have decreased both On and Off time and switching speed. At high frequency this can shock IGBT and blow it. \$\endgroup\$ – user2960039 Apr 4 at 9:43
  • \$\begingroup\$ That's good to know. Bear in mind this is a static switch, no high frequency switching--normally it will be closed. I decided to start at 20R as someone who has more experience than me recommended that as a good "rough" value. If I understand correctly, for the "off" resistor (OUT-, 3R3 in DS), smaller values mean more current and faster turn off (on top of ~2R internal resistance). Are smaller values generally better for the IGBT as long as the gate driver can handle the current? Also--do the two resistors need to differ from each other? \$\endgroup\$ – usinjin Apr 5 at 10:32
  • \$\begingroup\$ For static switching 20R probably OK for both. Getting them too small also not recommended as this can affect EMC (at high frequency) as well as gate di/dt on some sensitive IGBTs, but these are not your case. Difference of values because "switching off" or closing n-type IGBTs always harder than turning them "on" (opening). So closing requires higher negative current. \$\endgroup\$ – user2960039 Apr 5 at 13:12
  • \$\begingroup\$ Right. Perhaps that value will end up being a little high. I am also getting an oscilloscope to assist me in fine tuning values, including gate resistors. Your help has been invaluable, thank you. \$\endgroup\$ – usinjin Apr 5 at 20:48

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