when gate signal is removed from supply to non igbt,led is not turning off?

Discussion in 'Power Electronics' started by kittoo, Jul 18, 2016.

  1. kittoo

    Thread Starter New Member

    Jul 11, 2016
    25
    1
    dear sir,
    when i am applying a gate signal to the npn ibgt the led is on, which is connected between emitter & collector.
    If i removed gate supply to igbt still the led is glowing.
    what is the reason ?
     
  2. SLK001

    Well-Known Member

    Nov 29, 2011
    811
    224
    Probably some residual gate charge on the IGBT. Put a 10k resistor from the gate of the IGBT to ground.

    Always show your circuit if you have questions.
     
  3. kittoo

    Thread Starter New Member

    Jul 11, 2016
    25
    1
    Thanks for the reply
    I got the answer,even though the source is open circuited ,the igbt will have some internal capacitance. since it is not short circuited it will discharge through led.
     
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