幵關電源倍频點EMC超出

幵關電源倍频點EMC超出
幵關電源在EMI測試時,160M-170M超出,可以知道是倍频點,改變频率可PASS,大家可討論一下, 解決這方面EMI的方法.

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hereliu

LV.8

2004-02-18 18:26

大概是开关速度太快.
.

r00778

LV.4

2004-02-19 08:40

@hereliu

大概是开关速度太快..

可我的工作频率只有60KHz
這個频率應該不高

gwwater

LV.6

2004-02-19 16:23

您老的开关频率是75MHZ??
强烈疑问中

arthur.deng

LV.4

2004-02-20 21:15

Radiation solution
For 160M~180M band width, the root cause can be analysis as following:
1. Grounding impedance too high, you need to improve it.
2. Check the Vds spike, if the first spike is about 40M, 160M~170M should be fail, I just solve one project fail in this band width, so you can try it, I just adjusted clamper.

r00778

LV.4

2004-02-23 14:45

@arthur.deng

RadiationsolutionFor160M~180Mbandwidth,therootcausecanbeanalysisasfollowing:1.Groundingimpedancetoohigh,youneedtoimproveit.2.ChecktheVdsspike,ifthefirstspikeisabout40M,160M~170Mshouldbefail,Ijustsolveoneprojectfailinthisbandwidth,soyoucantryit,Ijustadjustedclamper.

Vds spike

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shenhuayong

LV.2

2004-02-23 15:14

@r00778

Vdsspike[图片]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){returntrue;}else{window.open('http://u.dianyuan.com/bbs/u/0/1077518452.bmp');}"onmousewheel="returnimgzoom(this);">[图片]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){returntrue;}else{window.open('http://u.dianyuan.com/bbs/u/0/1077518526.bmp');}"onmousewheel="returnimgzoom(this);">[图片]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){returntrue;}else{window.open('http://u.dianyuan.com/bbs/u/0/1077518591.bmp');}"onmousewheel="returnimgzoom(this);">[图片]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){returntrue;}else{window.open('http://u.dianyuan.com/bbs/u/0/1077518714.bmp');}"onmousewheel="returnimgzoom(this);">

我也遇到这个问题!我现在的电路在做传导时500K左右超标.开关频率100K
我也遇到这个问题!我现在的电路在做传导时500K左右超标.开关频率100K.共模电感加大点后超的更多了:(

arthur.deng

LV.4

2004-02-25 22:14

@r00778

There have some confuse
I thought your problem is conduction issue, right, so the band width should be 160K to 170K, not 160M to 170M, right? From your waveform, no problem for 160M to 170M radiation except the grounding problem. So for the conduction at 160K to 170K, modify frequency is a solution, but it is not a optimize solution, otherwise we can't run in higher frequency, ritht? So optimize common mode filter is a suitable solution, increase inductance or capacitance is the solution, but notice, do not increase the Y cap too high, it will impact the higher frequency band width and radiation, only increase inductance can solve it, you can use 10000u core, the inductance can over 20mH, I thought this should solve your problem, same as Huayong's solution. good luck to you.