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I am working to design a static AC switch using an IGBT module. The idea is that the switch will protect an inductive load from an adverse voltage condition (such as excessive under or over voltage) and disconnect the load from the mains. For now, it will need to switch single-phase 120VAC, and the load will be 1kW or smaller.

The IGBT module I have selected is an Infineon FF300R12KT3_E module (https://www.infineon.com/cms/en/product/power/igbt/igbt-modules/ff300r12kt3_e/), which features dual common-emitter IGBTs. My schematic shows a standard optocoupler, but I am considering using an Infineon 1EDC60H12AHXUMA1 IGBT gate driver or similar (https://www.infineon.com/cms/en/product/power/gate-driver-ics/1edc60h12ah/). This will be powered from an isolated 20VDC power supply, and controlled via microcontroller. I have the IGBT modules but not the gate driver yet.

Does this design seem robust enough for my needs? The circuit is based off an older design design by International Rectifier (Now Infineon). I am not sure the resistor between the gates and emitter is necessary. Actually, I'm wondering if anything else could be done that might protect the gate regions against turn off oscillations. Any feedback would be much appreciated.enter image description here

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  1. Your opto output doesn't make sense. All it does is short gate-source without ever applying a voltage to gate-source.
  2. IGBTs cannot conduct in reverse, which would mean either D1 or D2 would be carrying the full current of a particular polarity plus any associated forward conduction loss. Why are you using IGBTs instead of MOSFETs at such low voltages? MOSFETs can conduct through the MOSFET channel itself in reverse for lower losses.
  3. For gate ringing, place a series resistor for EACH gate as close as possible to the gate.
  4. If it is supposed to interrupt an inductive load, you will need snubbers across drain-drain.
  5. If you have inherently an isolated supply, consider applying a couple of negative volts to the gate-source during turn off. IGBTs can have turn off issues.
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  • \$\begingroup\$ Oops, that was kind of a silly mistake regarding leaving out the gate voltage source. I evidently didn't double-check. I originally thought using IGBTs might give more voltage/current overhead, but that makes sense about the FWD loss. \$\endgroup\$
    – usinjin
    Mar 17 '20 at 3:15

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