電力轉換器由於功率開關元件的高頻切換，產生快速變化的電壓dv/dt和電流di/dt，導致市電電源線受到嚴重地電磁汙染。本論文首先分析傳導性雜訊的量測原理、差模/共模雜訊分離法，及頻譜分析儀之量測參數。再探討DC/DC電力轉換器之雜訊源、干擾路徑，及其抑制方法，並以PSpice軟體之模擬結果和實作結果佐證之。
電力轉換器之雜訊源，主要來自MOSFET開關和整流二極體。其中，開關的切換雜訊與上升沿/下降沿時間、開關之導通率，及切換頻率有關。適當地減緩上升沿/下降沿時間，可有效抑制開關產生的雜訊。而整流二極體的切換雜訊與恢復電流之上升斜率有關，若能減緩恢復電流之di/dt，則可有效抑制二極體之切換干擾。
共模雜訊是傳導性干擾中，最難解決的問題。而電力轉換器之e共模雜訊，主要是由連接至機殼地之散熱片和隔離變壓器之寄生電容所引起的。依據共模電流i=C(dv/dt)，吾人可應用靜態節點之概念，使dv/dt=0 ，或將變壓器繞組中，具有高電壓變化的兩端點，設計在相距最遠的繞組上，以降低寄生電容 。吾人亦可應用平衡電路或共模電流抵消法。此外，可應用Y電容或屏蔽層，以困住共模電流，降低流至LISN之共模電流。
本論文係探討抑制電力轉換器共模雜訊的方法，以實作驗證理論分析的結果。提供電源工程師處理雜訊干擾時，針對雜訊的來源和傳導路徑，採取適當的抑制方法。

Power converters generate rapidly changing voltages and currents due to the switching actions of the power switch. Accordingly, the electromagnetic pollution introduced by line-connected power converters can propagate by conduction on the power line. In this thesis, the measuring principle of the conduction noise, differential/common mode noise separation and the measurement parameters of the spectrum analyzer will be described first. Then, the noise source, coupling paths in a DC/DC power converter, and the suppression methods of them will be discussed. In addition, PSpice simulations and experimental results are used to validate the theoretical analysis.
Major noise in power converters arises from the MOSFET switch and rectifier diode. The switching noise generated from MOSFETs is related to the rise/fall time, duty ratio and switching frequency. If the rise/fall time increases properly, the switching noise generated from MOSFET can be effectively suppressed effectively. On the other hand, the switching noise resulted from rectifier diode is related to the sharp edge of the current waveform when diode current returns to zero. If this current change rate di/dt of the recovery current is reduced, the diode switching noise can be thereby suppressed effectively.
The common-mode noise conduction interferences are the most difficult problem to be dealt with. They come from the charge and discharge of the parasitic capacitances of the heat sink and transformer windings in the power converter. Since the common-mode current is expressed as i=C(dv/dt)，the static point can be used to achieve dv/dt=0 and thus i=0. Additionally, the transformer winding terminals with high changing voltage can be placed far away from each other to reduce their parasitic capacitances. The balanced circuit method or common-mode current cancellation technique is useful to suppress the noise. Y capacitors or shields can be applied to besiege the common-mode currents. As a result, common-mode currents flowing through the LISN can be reduced.
In this thesis, common-mode reduction techniques in DC/DC power converters are investigated and validated by experimental results. For various noise sources and coupling paths, the noise suppression methods proposed in this thesis are beneficial for power engineers who suffer from noise problems in power electronics.

[CCB03] Cochrane, D., Chen, D. Y. and Boroyevic, D., “Passive Cancellation of Common-Mode Noise in Power Electronic Circuits,” IEEE Trans. Power Eletronics, Vol. 18, pp. 756-763, 2003.
[ChQ04] Chen, W., Qian, Z. M., “A Novel and Simple Approach to Suppress Common-mode EMI in Power Converters,” IEEE INTELEC, pp. 589-592, 2004.
[Eri01] Erickson, R. W., Fundamentals of Power Electronics, Kluwer Academic Publishers, Norwell, Massachusetts, USA, 2001.
[FeE01] Felic. G., Enans. R., “Study of Heat Sink EMI Effects in SMPS Circuits,” IEEE International Symposium on Electromagnetic Compatibility, Vol. 1, pp. 254-259, 2001.
[Flu91] Fluke, John C., Controlling Conducted Emissions by Design, Van Nostrand Reinhold, 1991.
[FR07] Fair-Rite Products Corp., “How to Choose Ferrite Components for EMI Suppression,” Technical Information, 2007.
[HP97] Hewlett-Packard Company, HP 11949B Designing for Electromagnetic Compatibility, Hewlett-Packard Company, 1997.
[JoC99] Jones, E. R., R. L. Childers, Physics, Third Edition, WCB/McGraw-Hill, 1999.
[Kai04] Kaiser, Kenneth L., Electromagnetic Compatibility Handbook, CRC, 2004.
[Knu88] Knurek, Dennis. F.,“Reducing EMI in Switch Mode Power Supplies,”IEEE INTELEC, pp. 411-420, 1988.
[MLT03] Masahits, S., Li, G.., and Tamotsu, N., “Balanced Switching Converter to Reduce Common-Mode Conducted Noise,”IEEE Trans. Ind. Electronics, Vol. 50, pp.1095–1099, 2003.
[Nav91] Nave, Mark J., Power Line Filter Design for Switched-Mode Power Supplies, Van Nostrand Reinhold, 1991.
[OdC03] Odell, B., Chan, W. P.,“Method and Apparatus for Substantially Reducing Electrical Earth Displacement Current Flow Generated by Wound components,”U.S. patent 6,549,431 B2, April 2003.
[Ott88] Ott, H. W., Noise Reduction Techniques in Electronic Systems, Second Edition, Wiley-Interscience Publishers, 1988.
[Pau06] Paul, C. R., Introduction to Electromagnetic Compatibility, Second Edition, John Wiley and Sons, Inc. 2006.
[Philips96] Philips Semiconductors, “Power Diodes,” Introduction, 1996
[PI96] Power integrations, “TOPSwitch Power Supply Design Techniques for EMI and Safety,” Application Note AN-15, 1996.
[Per95] Perez, Reinaldo, Handbook of Electromagnetic Compatibility, Academic, 1995.
[PWN97] Paul, C. R., K. W. Whites, S. A. Nasar, Introduction to Electromagnetic Fields, Third Edition, McGraw-Hill, 1997.
[Ral07] Ralph Morrison, Grounding and Shielding: Circuits and Interference, Fifth Edition, Wiley-IEEE, 2007.
[Red96] R. Redl, “Power Electronics and Electromagnetic Compatibility,” IEEE PESC, pp.15-21, 1996.
[SuP96] Sugasawara, D., Paetau, J., “Safety, EMI and RFI Considerations,” Application Note 42007, Fairchild Semiconductor, 1996.
[Tih95] Tihanyi, Laszlo, Electromagnetic Compatibility in Power Electronics, IEEE PRESS, 1995.
[VLNR99] Vallittu, P., Laurinen, T., Nisonen, I., Ritamaki, S., “Design for EMC in Switched-Mode Power Supplies,” EPE, pp. 1-9, 1999.
[Wil92] Williams, Tim., EMC for Product Designers, Butterworth-Heinemann, Oxford, 1992.
[Yee97] Yee, H. P., “An EMI Suppression MOSFET Driver,” Proceedings of IEEE Applied Power Electronics Conference and Exposition, Vol. 1, pp. 242-248, 1997.
[葉宇展07] 葉宇展，雜訊分析與防制對策之研究與驗證，碩士論文，國立成功大學工程科學系，2007。
[楊克俊06] 楊克俊，電磁相容原理與設計技術，全華科技圖書股份有限公司，2006。
[林國榮96] 林國榮，電磁干擾及控制，全華科技圖書股份有限公司，1996。
[三宅和司01] 三宅和司，電阻及電容器的適材適所，建興文化事業有限公司，2001。