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Single-phase full-bridge inverter with multiple pulse width modulation

  1. Nov 17, 2013 #1
    Hey guys. I have been theoretically playing around with a single phase full bridge inverter. What I wanted to do was determine the waveforms for the current going through each of the components (ie. the four diodes and the four thyristors). I assumed all of them were ideal. Since I have no idea how to simulate this, I was hoping someone here could verify if I have the correct logic in regards to my waveforms.

    For the positive ON cycles, thyristors Q1 and Q3 are on. For the negative OFF cycles, thyristors Q2 and Q4 are on. The antiparallel diodes are there due to reactive load.

    The reason I am unsure of my waveforms is I have only dealt with output cycles that go from positive to negative, then positive to negative, etc. This cycle goes positive positive positive negative negative negative, in regards to its polarity.

    Obviously the minimum/maximum values will depend on the values of the circuitry.

    Thanks in advance!

    Attached Files:

  2. jcsd
  3. Nov 18, 2013 #2


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    Staff: Mentor

    That looks about what I'd expect, except .... :smile:

    during the moment when the load has its current reversed.

    At that moment things will be a bit more apoplectic than you show, though I'm not sure what to expect, exactly --- you are trying to turn the thyristors on while they have reverse polarity. Are you going to use unusual gate drive signals to handle this?

    You are exemplifying a load with significant inductance, perhaps you could have a go at sketching the load voltage, too? :wink:

    I'd expect a web search would be turn up a good discussion of this. http://imageshack.us/a/img811/5412/thgooglefriend1.gif [Broken]

    BTW, I notice you adroitly avoided showing how you intend turning off those thyristors at the end of each pulse.
    Last edited by a moderator: May 6, 2017
  4. Nov 18, 2013 #3


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    Staff: Mentor

    "flywheeling" diodes is an apt name
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