3 Phase Rectifier

Discussion in 'General Electronics Chat' started by enigmapaul, Dec 12, 2008.

  1. enigmapaul

    Thread Starter New Member

    Dec 12, 2008
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    Hi,

    If I need a solid 350VDC output from a 3-phase generator, can someone point me to the equations to use to figure out how much peak to peak voltage I must maintain on the output of the generator to achieve the DC voltage out using a 3-phase rectifier?

    Thanks!
     
  2. bertus

    Administrator

    Apr 5, 2008
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    2,348
    Hello,

    When you rectify an 3 phase signal, the top voltage is the same as in a single phase.
    The avarage voltage will be higher as in a single phase, beacouse the ripple is much smaller.
    See also teh AAC eBook :
    http://www.allaboutcircuits.com/vol_3/chpt_3/4.html

    Greetings,
    Bertus
     
  3. enigmapaul

    Thread Starter New Member

    Dec 12, 2008
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    0
    Thanks what is the equation to determine the average DC voltage output of the 3 phase rectifier?

     
  4. bertus

    Administrator

    Apr 5, 2008
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  5. mik3

    Senior Member

    Feb 4, 2008
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    Vdc=1.35*VL

    Vdc=output voltage of the rectifier
    VL=RMS value of the line voltage
     
  6. SgtWookie

    Expert

    Jul 17, 2007
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    That's an extremely rough approximation even at low voltages, and the accuracy is much worse at higher voltages.

    A closer approximation would be:
    Vdc=1.4142*(VL-VF)
    where:
    Vdc= output of the rectifier
    VL = RMS of the line voltage
    VF = Forward voltage of the rectifier(s) in series
    But this still does not account for smoothing capacitors and current in the circuit.
     
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