Huge spikes at output voltage

Discussion in 'The Projects Forum' started by Tahsina Hossain, Mar 3, 2015.

  1. Tahsina Hossain

    Thread Starter Member

    Jan 16, 2015
    40
    0
    Hi there everyone,

    I have developed a single phase full bridge inverter but at the output I am observing huge spikes, what confuses me most is that: I have spike across one node to ground but not on the other.

    I have always got constructive and useful feedback from this forum, please help me this time as well.

    I am using bipolar spwm from msp430 to generate the control pulses. 20150303_145834.jpg
     
  2. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,979
    744
    A circuit would help us further...
     
  3. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    Useful information from us requires useful information from you.
    Please post a circuit diagram.
     
  4. Denesius

    Member

    Feb 5, 2014
    89
    14
    Is there an inductor in the output circuit somewhere?
     
  5. Tahsina Hossain

    Thread Starter Member

    Jan 16, 2015
    40
    0
    Hi there,

    Yes, I should have posted the circuit earlier, was so caught up in the spike thing, I dont have any sort of inductor in the output circuit.
     
  6. Sensacell

    Well-Known Member

    Jun 19, 2012
    1,128
    266
  7. #12

    Expert

    Nov 30, 2010
    16,261
    6,774
    It looks like 4 gate drivers running 4 IGBTs but the gates are drawn differently. Does that mean this is not a matched set of 4?
     
  8. uwed

    Member

    Mar 16, 2015
    64
    17
    Looks very much like classic overvoltage spikes due to parasitic stray inductances in the commutation path.
    You can reduce switching speed (defined by gate-resistance) which might unfortunately increase switching losses. And you should take care about a low-inductive circuit design on your PCB.

    Here is a nice animation (Java-applet) which shows what might be going on: http://www.ipes.ethz.ch/ipes/switching/e_niederind.html
    (works only if Java-applets are allowed by the browser)
     
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