Parallel IGBT with MOSFET

Discussion in 'General Electronics Chat' started by khalid4145, Nov 20, 2008.

  1. khalid4145

    Thread Starter Member

    Jul 22, 2008
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    0
    Hi guys,,,

    Would it be possible to parallel IGBT with MOSFET? I have an IGBTs in my design. i want to put MOSFET (electronic switch controlled by microcontroller) in parallel to the IGBT to generate a short circuit across the IGBT. Please see the attachment.
     
  2. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    As long as the emitter of the IGBT is at the same potential as the Vss/ground of the microcontroller, sure.

    If it isn't, you will very likely damage the uC and/or the MOSFET.

    An IRLZ34 or IRLZ44 would be a likely MOSFET candidate.
     
  3. khalid4145

    Thread Starter Member

    Jul 22, 2008
    16
    0
    Actually the IGBT is driven from optocoupler driver circuit which isolate the PWM input of the microcontroller and the driver circuit of the IGBT. Thats means the IGBT and logic level MOSFET has different grounds. How can i solve the proplem??? I am using another circuit to measure or sense the voltage across the IGBT as shown in the following attachements. Please advice does the circuit make sense?
     
  4. SgtWookie

    Expert

    Jul 17, 2007
    22,182
    1,728
    You're not showing enough of the circuit.

    In the upper diagram, you show an 8A current coming towards the collector of the IGBT, and a wire dangling from the IGBT's emitter. You can't have current flow if there is no path to ground.

    You do not show where the load is for the IGBT; I'm assuming it is about 3.75 Ohms in resistance?

    It is preferable to post your schematic and waveforms as .png or .gif graphics rather than Word documents; they take up much less space on the Board and load much faster for those trying to help you.
     
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