急寻“电源带载能力太差,占空比太小”的原因

我用top222y制作了一开关电源．算出85v交流输出时直流电压最小值为97V,一次绕组反射电压 取135V,得出最大占空比Dmax=Vor/【Vor+Vmin-Vds(on)】=0.53,Vds(on) 是top222y导通期间漏极-源极的平均电压值 ,取10V
  原边用AWG30导线绕57匝,+5V、+12V、±15V及反馈绕组用AWG24导线分别饶3匝、7匝、9匝、7匝.
  从实测波形可以看出(1)从85v输入,满载的波形看出Dmax约8%,太小(2)空载时主输出约5.2v,带满载时输出电压太低,约1.2V
  电路原理图和波形图见附件．
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