混模雜訊效應在離線式電源電磁干擾濾波器上之濾除機制及設計

Effects of Mix-Mode Noise on the Filtering Mechanism and the Design Procedure of Off-line Power Supply EMI Filters

謝宏毅(Hung-I Hsieh)

指導教授 ： 陳德玉

國立臺灣大學/電機資訊學院/電機工程學研究所/博士(2007年)

https://doi.org/10.6342/NTU.2007.03056

摘要

依據傳統的理論，傳導性雜訊之分析方法一般可區分為差模和共模兩種雜訊型態，然而對於僅將傳統理論應用在雜訊分析和濾波器設計上而言，仍稍有不足。本論文針對近年來所提出之傳導性電磁干擾雜訊概念，混模雜訊（Mix-Mode EMI Noise），進行研究，並且將新的研究認知應用在濾波器的設計上。
本論文提出三種新理論。一為雜訊電流平衡（Noise Current Balancing）概念。此概念為利用電容性濾波器元件作為消除由系統上之寄生電容所產生的混模雜訊電流，以達成雜訊抑制之目的。二為共模雜訊抑制電容（Z Capacitor）之研究，本論文首次針對此一電容對於雜訊抑制的原理與機制作深入解釋和探討，並提出使用建議。此外也針對不同轉換器之電路架構提出相關的使用方法。同時於本論文中也提及變壓器的纏繞結構，與其不同纏繞方式所產生之相對應的寄生電容，對於雜訊路徑耦合的影響。實驗與模擬結果也皆能符合所提出之理論。三為提出一套快速且有系統之包含混模雜訊效應的電磁干擾濾波器設計流程。將其與傳統設計流程的結果做比較，本論文所提出之設計方法能更夠有效減少濾波器元件體積，進而達到濾波器精簡化與節省成本之目的。

關鍵字

混模雜訊 ； 差模雜訊 ； 共模雜訊 ； 阻抗不匹配 ； 電流平衡 ； Z電容 ； 雜訊分離器

並列摘要

Conducted electromagnetic interference (EMI) noise was traditionally classified into two coupling modes, differential-mode (DM) and common-mode (CM). But there were phenomena unexplainable with this traditional theory. An additional noise-coupling mode, the mix-mode (MM), was then proposed to fill this inadequacy. The main focus of this dissertation is to explore the mix-mode noise coupling mechanism even further and use the new understanding to improve practical EMI filter designs.
Specifically, three areas were explored. One was to look at the new role in one differential-mode capacitor (X capacitor) and two-serial common-mode capacitors (Y capacitors) play in filtering mechanism. Besides the conventional impedance mismatching concept, a “noise current balancing” concept was introduced. Second area of exploration was about a common-mode capacitor (Z capacitor) connection in a two-wire system which is common in many hand-held device applications. The effectiveness of such common-mode capacitor was not clear before. An explanation with the mix-mode phenomenon was proposed in this dissertation. From this proposed theory, several practical common-mode capacitor connecting means were proposed. Experiments were conducted to prove the theory. The third area of exploration was to incorporate the mix-mode considerations into a practical EMI filter design. It’s concluded that with this new approach, smaller EMI filter can be achieved.

並列關鍵字

Mix-Mode (MM) ； Differential-Mode (DM) ； Common-Mode (CM) ； Impedance Mismatch ； Current Balancing ； Z Capacitor (Cz) ； Noise Separator

參考文獻

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