EMI Filtering -- How to Get the Lowest Noise (A Vicor Power Techtorial)

Focus:

Video discusses the noise sources and requirements for conducted EMI filtering in switched-mode power supplies. The causes of common-mode and differential-mode noise in switched-mode power supplies are explained; and the components used in EMI filtering are presented. The impact of placement of bypass capacitors on radiated EMI is discussed. A setup is presented for testing the compliance of a dc-dc converter module with EN55022 Class B Quasi Peak limits on conducted EMI. The setup consists of a linear power supply, a line impedance stabilization network (LISN), a spectrum analyzer, and a computer for processing the test data. Measurements are taken with no EMI filtering, then with Y capacitors, and finally with an EMI filter consisting of a common-mode choke plus 2 differential mode chokes and an X capacitor.

What you’ll learn:

• How to understand causes of common-mode and differential-mode noise in switched-mode dc-dc converters
• How to measure conducted EMI on input of dc-dc converters for compliance with EN55022 Class B requirements
• How to reduce conducted EMI on dc-dc converter inputs using different forms of filtering

Notes:

One of Vicor's video tutorials.

View the Source

Author & Publication:

Peter Huber, Senior Field Applications Engineer, Vicor, Germany, Vendor website, Dec 31 2008

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