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．
  谢谢各位高手帮忙!感激!1168917713.doc500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/49/1168917745.gif');}" onmousewheel="return imgzoom(this);">500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/49/1168917761.gif');}" onmousewheel="return imgzoom(this);">500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/49/1168917840.gif');}" onmousewheel="return imgzoom(this);">500) {this.resized=true; this.width=500; this.alt='这是一张缩略图，点击可放大。\n按住CTRL，滚动鼠标滚轮可自由缩放';this.style.cursor='hand'}" onclick="if(!this.resized) {return true;} else {window.open('http://u.dianyuan.com/bbs/u/49/1168918450.gif');}" onmousewheel="return imgzoom(this);">