FET Switching problem

Discussion in 'General Electronics Chat' started by yakuut, May 7, 2011.

  1. yakuut

    Thread Starter New Member

    Sep 21, 2009
    7
    0
    Hi there,
    I am having some problem with N-channel low side switching.I am trying to control a 12V 30 amps brushed DC motor using PWM.I am using IRL3705 as the FET and IRS4427 as the Low side gate driver.The switching frequency is 32Khz.The gate resistor has a value of 4.7 ohm. I have STTH6004W as the flywheel diode and a electrolytic 100uf DC link capacitor with a metalized polyester film capacitor of 0.1uf in parallel to it.The problem is that I am 100% voltage spikes at the drain of the FET.What could be the reason ??
     
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  2. miguel cool

    New Member

    Mar 15, 2010
    9
    0
    Please, if you can, put the graphics of the signals, at gate, Drain, and Vcc.

    Thanks
     
  3. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,670
    804
    Try a small cap across the motor, like 10nF.
     
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