External Power Supplies And The New Level VI Specifications: Evolution Or A Different Species?

Focus:

A new generation of external power adapters is entering the market and they are significantly different from their predecessors. What’s driving these changes is the new Level VI specification of the International Energy Efficiency Marking Protocol for External Power Supplies, which was published in 2014 by the U.S. Department of Energy and is scheduled to take effect in the U.S. in February 2016. At the time of adoption, it will be the toughest efficiency specification in force anywhere in the world. This article describes the changes to the energy efficiency protocol versus the existing Level IV and V specs including Level VI’s expanded scope, modified power supply categories, coverage of higher power levels, and tighter limits. Two tables conveniently summarize the old and new specifications. The article also describes in broad terms how the author’ company (CUI) has modified its adapter designs to meet the new requirements. These changes include choice of topology, use of synchronous vs. non-synchronous rectification, choice of switching frequency and its reduction at light load, disabling of PFC at light load and others. Measurements of Level V and VI adapters illustrate the improvement in efficiency.

What you’ll learn:

• How to understand the efficiency requirements imposed on external power supplies by the U.S. DoE’s Level VI protocol
• How to improve adapter efficiency to meet Level VI requirements
• How to understand how the Level VI energy efficiency specification differs from Levels IV and V

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Author & Publication:

Jeff Schnabel, CUI, Tualatin, Ore., How2Power Today, Aug 15 2015

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