現今的科技日新月異，電子業蓬勃發展，產品往輕薄短小發展，數位化更是趨勢，速度的要求也愈來愈快，因此EMI的問題也越趨嚴重。電源供應器因為切換式技術的產生，體積也日趨縮小，也因為使用切換式的技術致使需要考量EMI的問題。本論文單就傳導型EMI的問題做一探討。

傳導型EMI的解決方式通常是加一個電源濾波器在電源端的入口，以抑制雜訊從電源線傳出。因此設計這個濾波器是解決傳導型EMI的關鍵，能夠很快速且有效率的將濾波器設計出來是每一個工程師的目標。其中傳導型EMI的雜訊分兩個模態，共模訊號和差模訊號，濾波器的設計和雜訊的模態有密切的關係，因此能將雜訊分開將對工程師設計濾波器有很大的幫助，可以縮短設計時間及成本。目前常用的雜訊分離器有很多，各有優缺點。本論文提出一組新的分離器，可分別檢測共模和差模雜訊，他們不但是成本較低，製造也較容易，工程師可以很容易的在市面上找到所需的材料，做成分離器。除此之外，這組分離器量到的雜訊大小就是實際的量不需做調整。

最後，配合這組分離器，運用已知的設計濾波器方法寫成一個自動量測系統，工程師在用頻譜分析儀量完雜訊的同時，這套軟體將會算出濾波器的元件值給工程師做為設計濾波器的參考。又因為頻譜分析儀價格昂貴，或是其他因素無法使用頻譜分析儀。因此本論文提出用較便宜的示波器來做量測工具，代替頻譜分析儀。先量出時域訊號再做傅立葉轉換到頻域做計算。當然本論文也將它寫成一套自動量測的系統，更好的是它不需要分離器可以直接將共模及差模的雜訊分出，量完的同時也算出濾波器的元件值做為工程師設計時的參考。

Nowadays, electronics has really flourished with the rapid progress in science and technology. Besides being light and efficient of the products, digitalization and faster speed are also required which make the problem of EMI, electromagnetic interference, become more serious. Newer power supplies using switching technology become smaller and smaller. However, they also produce EMI problems that need to be considered. In this thesis, we only address the conducted EMI.

Generally, the noise is suppressed by adding a filter at the power-line end. Hence, the EMI filter plays an important role to the solution of conducted emission. The particular filter is related to the type of the conducted emission, including common-mode and differential-mode. As a result, it is a great help for an engineer to be able to separate the noise. There are several noise separators in the present days. We propose new separators, which are capable of detect common-mode and differential-mode separately. Our separators are low-cost, easily manufactured and are able to give exact noise readings without adjustment.

Incorporating the known methods of filter design and combing programming measurement the filter design can be made automatic. One approach makes use of the spectrum analyzer, which is considered to be a relatively expensive instrument. We also propose another approach using oscilloscope. The time-domain measurement is performed and transformed into frequency domain using FFT. A realistic design example is shown to give satisfactory results.

誌謝 i
中文摘要 iii
英文摘要 iv
目錄 v
圖表目錄 vi
第一章 緒論 1
1-1 研究背景 1
1-2 論文編排 1
第二章 傳導型EMI的量測 2
2-1 傳導型EMI的規範 2
2-2 量測傳導型EMI的配置 5
2-3 LISN 的介紹 6
2-4切換式電源供應器之傳導型EMI的產生 8
第三章 各類輔助工具 12
3-1 差模拒斥電路 12
3-2 功率結合器 14
3-3 加減法器
( a device for adding and subtracting phase and neutral ) 16
第四章 共模、差模檢知電路 17
4-1 共模檢知電路 17
4-2 差模檢知電路 20
第五章 電源濾波器設計的軟體化 23
5-1電源濾波器的理論及方法 23
5-2 電源濾波器設計 -------- 使用頻譜分析儀 27

5-3 電源濾波器設計 -------- 使用示波器 30
第六章 實例 33
6-1 使用頻譜分析儀做量測 33
6-2 使用示波器做量測 36
第七章 結論與未來方向 39
7-1 結論 39
7-2 未來方向 40
參考文獻 41

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