Leakage Inductance (Part 2): Overcoming Power Losses And EMI

Focus:

In most isolated converters, leakage inductance contributes to both power losses and EMI, but there are ways in which power losses and EMI can be avoided by design. The first course of action is to design the transformer for low leakage inductance, but sometimes that approach is too costly or requires more space than is available, so other methods are needed. In this part 2, the various clamp and snubber options are discussed including RCD clamp, RC snubber, LCD clamp and active clamps. The pros and cons and varying requirements of the different approaches are discussed mainly within the context of the flyback topology, but also touching on the LCD clamp in the single-ended forward converter, and active clamps in the coupled-boost converter. Finally, this part looks at techniques for improving load regulation degraded by leakage inductance.

What you’ll learn:

• How to understand leakage inductance-induced ringing in flyback converters
• How to reduce leakage inductance-induced EMI and power losses using clamps and snubbers
• How to design snubbers and clamp circuits

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Author & Publication:

Ernie Wittenbreder, Technical Witts, Flagstaff, Ariz, How2Power Today, Nov 16 2015

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