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IGBT gate resistor for switching application

  1. Apr 13, 2017 #1
    The problem statement, all variables and given/known data
    I have a 560 ohm gate resistor on an IGBT. Usually an IGBT doesn't require a gate resistor as it already has a high impedance of its own, but I'm told that for switching applications a gate resistor can be beneficial.

    The attempt at a solution
    If there is a gate resistor, will it not slow down the switching speed of the IGBT? Why then would I require a resistor at the gate?
     
  2. jcsd
  3. Apr 13, 2017 #2
    The gate has capacitance, very low resistance can cause a gate ringing due to parasitic inductance in the gate circuit. The resistor impacts many factors, it may be necessary to slow the IGBT down to reduce di/dt or EMI, to limit the peak current from the driver.

    Some various references - there is no one answer - it is worth reading all of them through. But nothing beats blowing a few up and then figuring out why...:wink:
    ON Semi
    Infinion / IR
    Semikron

    These references above are typically for larger IGBTs - but your 560 ohm seems very high, I have not seen an IGBT using Rg that high. I just looked up a small IGBT 600V/30A and the Rg was 22 Ohms.

    As a rule of thumb we start with 150% of the value used for the IGBTs characteristics in the Datasheet, as these tend to be ideal conditions and done to make the IGBT switching look as good as possible - but realistic.
     
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