flyback converter

Discussion in 'General Electronics Chat' started by pini200, Feb 28, 2016.

  1. pini200

    Thread Starter New Member

    Feb 15, 2016
    14
    0
    Hi
    i have a problem
    i build ac dc converter based on flyback and i get in outpout sawtooth with rippel 1v
    i should get stable voltage in outpout
    input: 110-230Vac,outpot 12v 1A
    i used chip viper37LD and isolated feedback
    pic.PNG pic.PNG
     
  2. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    783
    You could have Trr trouble in the rectifier - a Schottky barrier type is faster, as long as you keep within its low reverse voltage rating.

    You may also need a LC Pi network as the output filter, use wire about 2 - 3mm dia - about half dozen or so turns on a ferrite slug.

    The output filter electrolytic(s) need to have very low ESR - you could also add film capacitors in parallel, at least 0.22uF.
     
  3. pini200

    Thread Starter New Member

    Feb 15, 2016
    14
    0
    it does not help
    i think the problem with feedback chip
    If you have other suggestions?
     
  4. Dodgydave

    Distinguished Member

    Jun 22, 2012
    4,979
    744
    Have you built this circuit or is it ready-made on a pcb?
     
  5. Roderick Young

    Member

    Feb 22, 2015
    408
    168
    Are you sure you have the phasing right on that transformer? Could it be that you are rectifying the forward part of the pulse, and not the flyback?
     
  6. ian field

    Distinguished Member

    Oct 27, 2012
    4,415
    783
    Forward conduction in a flyback converter would be obvious by the low output.

    If you increased the secondary turns to correct it - you'd soon find out if the rectifier didn't have high enough PIV rating.
     
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