Phase shift

Discussion in 'General Electronics Chat' started by TAKYMOUNIR, Mar 16, 2012.

  1. TAKYMOUNIR

    Thread Starter Active Member

    Jun 23, 2008
    351
    1
    Some power supply they use pwm to control the output and some use phase shift ,so what is difference between them
    thanks
     
  2. BillB3857

    Senior Member

    Feb 28, 2009
    2,400
    348
    One way to look at it is that phase shift is in reference to a fixed frequency. PWM may or may not hold a fixed frequency. Others will no doubt have other explanations.
     
    TAKYMOUNIR likes this.
  3. crutschow

    Expert

    Mar 14, 2008
    13,000
    3,229
    PWM power supplies vary the duty-cycle of a fast switch connected to the rectified DC to control the output voltage efficiently.

    SCR supplies vary the phase shift of the SCR firing point with respect to the AC waveform. The SCRs are part of the AC input rectifier bridge to control the DC output voltage. Generally with this scheme you need to add some type of linear regulator to provide a low noise output.
     
    TAKYMOUNIR likes this.
Loading...