The Engineer’s Guide To EMI In DC-DC Converters (Part 8): Common-Mode Noise Mitigation In Isolated Designs

Focus:

DC-DC converters operating at a high input voltage—such as the phase-shifted full-bridge and LLC series resonant converter in applications such as electric vehicle onboard charging, data center power systems and RF power amplifier supplies—can generate large CM currents. The effect is more pronounced when applying gallium-nitride (GaN) switching devices, as they switch at higher dv/dt than their silicon counterparts. A wide variety of techniques exist for mitigating CM noise in isolated dc-dc designs, including symmetrical circuit arrangements, connecting a capacitor between primary and secondary grounds, shielding, adding balance capacitors, optimizing transformer winding design and using an adjustable CM cancellation auxiliary winding. This article reviews these techniques, focusing mostly on flyback circuits.

What you’ll learn:

• How to mitigate common-mode noise in isolated dc-dc converters
• How to reduce CM EMI generation through choice of power supply topology, use of capacitors, and transformer design
• How to reduce CM EMI generation through transformer design including use of shielding and winding techniques

View the Source

Author & Publication:

Timothy Hegarty, Texas Instruments, Phoenix, Ariz., How2Power Today, Feb 15 2019

This article summary appears
in the HOW2POWER Design Guide.

The Design Guide offers
organized access to
hundreds of articles
on dozens of power conversion
and power management topics.

The Design Guide search results
include exclusive summaries
and accurate "how to" analysis
to help you make faster,
more informed decisions.

Search
for more articles