输入电压:80V---300V 效率:70%
多路输出: 12V 0.5A
12V 0.4A
12V 0.4A
12V 0.2A
-12V 0.2A
电源拓扑 反激,开关频率暂定f=100kHz,则周期https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-21701.png。https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-8413.png,电路工作在DCM模式,其中https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-16443.png是在输入电压为最小值时取的最大占空比。
1. 磁芯材料的选择和尺寸的计算
选择新康达公司LP3材料,100℃饱和磁感应https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-31778.png,https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-19350.png
磁芯选择新康达公司的EER2828(与EC28的尺寸几乎相同)
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-8240.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-13359.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-29374.png https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-30615.png https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-22253.png
2.最小输入直流电压https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-8440.png
3.最大输入直流电压https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-13725.png
4.输出功率https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-24204.png
这里取输出功率25W 变压器的效率定为70% https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-12694.png
5.原边峰值电流https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-1957.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-11747.png
工作在DCM模式下 https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-16411.png https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-16394.pngDCM模式下,https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-3110.png时间内电流0到https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-13579.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-32734.png
由https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-18251.png得 https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-20483.png
6.初级电感量https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-21713.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-30135.png
假设https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-8324.png波动下限为5%,则https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-25934.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-15951.png
7.计算气隙长度https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-6244.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-2379.png 式中 H-----气隙磁场强度
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-28118.png-----气隙的体积,https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-15462.png
整理得https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-13907.png
8.原边匝数https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-18723.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-15005.png
或 https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-9567.png
原边取28匝。
9.副边匝数计算https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-12471.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-20549.png 式中https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-32652.png为二极管压降
整理的https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-4050.png
带入数据 https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-27867.png匝
9.重新核算https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-13216.png
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-28518.png 得https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-20167.png
10.重新核算原边峰值电流
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-28598.png
11.计算导线尺寸
原边有效值https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-10782.png
选取电流密度5A/https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-21499.png,原边导线截面积https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-31004.png
副边1路输出有效值https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-22465.png=0.5A,1路输出导线截面积https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-28457.png为
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-30366.png
2路和3路输出有效值https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-39.png=0.4A,2、3路输出导线截面积为
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-11886.png
4路和5路输出有效值https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-27864.png=0.2A,4、5路输出导线截面积https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-6555.png为 https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-8056.png
12.验证是否磁饱和
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-23776.png
13.计算辅助绕组
UC3842稳定工作的电压https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-7518.png设为13V,
https://bbs.21dianyuan.com/file:///C:/DOCUME~1/CAOLAI~1/LOCALS~1/Temp/ksohtml/wps_clip_image-176.png N取5匝 |