LTSpice: 3-phase bridge ripple is 180Hz instead of 360Hz

Discussion in 'General Electronics Chat' started by darwin513, Jun 10, 2013.

  1. darwin513

    Thread Starter New Member

    Jun 9, 2013
    3
    0
    I created a three phase bridge circuit in LTSpice as shown in the attachment. The phase voltages & line voltages look good. However, the ripple of the dc is only 180Hz...it should be 360Hz!!

    Can someone please shine some light on what is going on here?

    I would greatly appreciate it.
     
  2. panic mode

    Senior Member

    Oct 10, 2011
    1,318
    304
    you grounded dc negative....
     
  3. darwin513

    Thread Starter New Member

    Jun 9, 2013
    3
    0
    Thank you for the response...

    I removed the ground on the negative side of the diode and the output waveform does not change.
     
  4. kubeek

    AAC Fanatic!

    Sep 20, 2005
    4,669
    804
    True, none of the phases should change if they are ideal sources, so maybe you should be plotting V(r1) instead?
     
  5. crutschow

    Expert

    Mar 14, 2008
    12,977
    3,220
    As kubeek noted you need to plot the voltage across R1, not R1 to ground, or plot I(r1).

    Alternately you could remove the ground on the sources and ground R1. That will give you the correct voltage waveform from the top of R1 to ground.
     
  6. darwin513

    Thread Starter New Member

    Jun 9, 2013
    3
    0
    I plotted the voltage across r1 and that provided the correct pulsed output -- see first attachment.

    Removing the ground from the sources creates a double-humped input waveform per phase -- see second attachment

    I really appreciated all your help...I am a LTSpice newbie, but I can really see its potential in power electronics.
     
Loading...