Unexpected Oscillations in PSpice Simulation

Discussion in 'Homework Help' started by mghg13, Sep 10, 2014.

  1. mghg13

    Thread Starter Member

    Jul 17, 2013
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    Hello Guys,

    I have implemented a simple half-wave SCR rectifier with RL load on PSpice. The supply has amplitude 50V and period 20ms. The firing angle of the SCR is 90°. I simulated the circuit and generated the transient plot for load voltage. The waveform obtained was almost as expected in theory except for one feature: At the extinction angle, there are some small oscillations before the load voltage gets back to zero.

    See the waveform below for only one cycle (i.e. 20 ms)
    load voltage (one cycle).png

    What is the explanation for this?
    Thanks
     
  2. MikeML

    AAC Fanatic!

    Oct 2, 2009
    5,450
    1,066
    Zero loss capacitors (no esr), no wire inductance, no wire resistance...

    Real circuits show this tendency but to a much lesser extent than simulation using ideal components...
     
    mghg13 likes this.
  3. mghg13

    Thread Starter Member

    Jul 17, 2013
    63
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    Can you please elaborate?
     
  4. bertus

    Administrator

    Apr 5, 2008
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  5. mghg13

    Thread Starter Member

    Jul 17, 2013
    63
    0

    OK, but why do the oscillations occur only at the discontinuities? And why only at the extinction angle and not the firing angle (because there is a discontinuity there also)?
     
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