Effects of X Capacitors on EMI Filter Effectiveness

Author

Hsieh, Hung-I ; Li, Jhong-Shu ; Chen, Dan

Author_Institution

Nat. Taiwan Univ., Taipei

Volume

55

Issue

2

fYear

2008

Firstpage

949

Lastpage

955

Abstract

The suppression mechanism of the differential-mode noise of an X capacitor in offline power supplies is, for the first time, attributed to two distinct concepts: 1) impedance mismatch (regarding a line impedance stabilization network or mains and the equivalent power supply noise source impedance) and 2) C(dv/dt) noise current balancing (to suppress mix-mode noise). The effectiveness of X capacitors is investigated with this theory, along with experimental supports. Understanding of the two aforementioned mechanisms gives better insight into filter effectiveness, which may lead to a more compact filter design.

Keywords

electromagnetic interference; impedance matching; interference suppression; power capacitors; power filters; power supply circuits; switching convertors; EMI filter effectiveness; X capacitors; compact filter design; differential-mode noise; impedance mismatch; noise current balancing; offline power supplies; suppression mechanism; Capacitors; Circuit noise; Delta modulation; Diodes; Electromagnetic interference; Filters; Frequency; Impedance; Noise generators; Power supplies; Impedance mismatching; Mix-mode (MM) EMI noise; impedance mismatching; mix-mode (MM) electromagnetic interference (EMI) noise; noise current balancing;

fLanguage

English

Journal_Title

Industrial Electronics, IEEE Transactions on

Publisher

ieee

ISSN

0278-0046

Type

jour

DOI

10.1109/TIE.2007.896258

Filename

4391031