Electronic Design
Power Forecast: New Regs for Energy Efficiency Challenge EPS Makers

Power Forecast: New Regs for Energy Efficiency Challenge EPS Makers

Remember the fuss in 2006 when the California Energy Commission imposed a half-watt standby requirement on "wall-warts?" This time around, power-supply makers are ready for, and eager to comply with, new international standards.

Gary Bocock, Director of Engineering, XP Power

Government directives for operational and standby efficiency in external power supplies have represented design challenges to power supply companies since the early 1990s, when U.S. Department of Energy Energy Star standards were released under the Energy Independence and Security Act (EISA). There was a major flap in 2006, when the California Energy Commission (CEC) introduced a half-watt standard for standby efficiency in the common “wall-wart” ac-dc supplies used to power or charge most home electronics.

According to Gary Bocock, director of engineering, XP Power, today’s new regulations come via Energy Star and the CEC in the U.S, the energy-related EU Code of Conduct (CoC) in Europe, Natural Resources Canada (NRCan), and the Minimum Energy Performance Standard (MEPS) standards in Australia, among others.

For the time being, the limits set in these standards are voluntary, but are more stringent than those required by legislation. Still, it is inevitable that the mandatory requirements will also become more stringent in the future as newer standards are adopted.

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What’s happening now is that both Energy Star and the EU CoC have set new, more demanding standards for both energy efficiency and no load power consumption. For example, the EU CoC has introduced a new two-tier load efficiency requirement expressly for applications that spend most of their time using minimal power from the external power supply (such as those with an internal battery) and has two tiers to drive future development.

It was only last year that Energy Star level VI and the EU CoC tier-2 requirements were both introduced, with their voluntary (for now) requirements coming into force in 2016. (See the tables for details and implementation dates.)  Note that Energy Star limits now apply to external power supplies with output capabilities up to and beyond 250 W.

The power market is fast moving; customers are keen to design in products that perform to the latest standards and are future-proofed. The first energy efficiency level VI parts are already available, and 2015 will see a significant increase in products released to market offering conformance to the very latest energy efficiency requirements.  For example, with its VER & VEL series of 5-W wall plug adaptors, XP Power is believed to be one of the first plug top power supplies to comply with the new Energy Star level VI energy efficiency standard. There are two versions: one with a fixed input plug (as required for use in the U.S., UK, Mainland Europe, or Australia), and another with four interchangeable main plugs for the rest of the world.

To get an idea of how the new requirements scale across the spectrum from point-of-load regulators through large internal and external supplies, I spoke with Bocock, Dr. Fariborz Musavi (director of engineering at CUI Inc.), and Patrick Le Fèvre (marketing and communication director at Ericsson Power Modules), asking essentially the same questions of each.

Tuite: As end products shrink in size but the demand for power goes up, what are the challenges power designers are facing in order to achieve increased conversion efficiencies?

Dr. Fariborz Musavi, Director of Engineering, CUI

As the power goes up, several challenges are introduced to power designers. The converters must be designed with not only significantly increased output current and higher efficiency, but also faster transient response, lower output voltage, and tighter output voltage regulation. In addition to these complexities, heat management and board real estate are extremely challenging. To meet these stringent requirements, the power designers must come up with several solutions in order to be able to address them all. This could be a mix of new power topologies, more efficient packaging, advanced control schemes, and improved semiconductor technologies for converting high power efficiently.

Patrick Le Fèvre, Marketing

  Over many years, efficiency has largely been related to improvements in switching components and innovative topologies that reduce switching losses. Also, increasing performance of magnetic components has made it possible to store more energy with smaller ferrites. But further major improvements are becoming increasingly challenging. As most regulated dc-dc converters are in the 96% efficiency range, getting closer to the mythical 100% will require improvements in components and better energy management within the switching unit. For example, advanced digital control can optimize energy transferred on a single pulse enabling the flattening of energy performance to an optimum level for either a low or high load.

Bocock: Achieving higher efficiencies is all about the cost, both in terms of the final product cost and the cost to develop a higher-efficiency power supply. Naturally there is a perceived market price for any product, too. We know we could make even more efficient products but even an extra 1% of efficiency could add up to significantly more cost. For example, the humble bridge rectifier is a high-volume, low-cost commodity product. An even more efficient rectification could be achieved with two MOSFETs, an inductor, and a control circuit, but those components could cost up to 10 times that of the bridge rectifier.

Tuite: Is there increasing demand in the market for a more efficient dc-dc conversion process, or is it the same as for ac-dc? What are you experiencing from your customers?

Bocock: Customers will always want more power from a given space. This is especially true for dc-dc converters, which are usually board-mounted. In the main, regarding increasing efficiency, customers have the same needs whether for dc-dc or ac-dc, and regardless of application or market sector. More power from a given space is good. It allows designers to make their end products smaller or to incorporate more functionality in the same footprint.

Musavi: We absolutely see an increasing demand for more efficient dc-dc conversion processes. It is not only to address the increasing cost of energy and meet all of the new energy efficiency standards, but to condition power at higher power rates and smaller sizes; power designers must design their converters more efficiently to be able to package them in such a small real estate.

Le Fèvre: The cost of energy has a direct impact on OPEX, sustainability, and carbon footprint, so the reduction of power consumption is important. Ericsson primarily designs board-mounted products and reducing losses and improving power conversion has driven the portfolio to anticipate customer demands. However, the power conversion ratio has reached a point that now requires new ways of converting power.

Tuite: What power range (low, mid, high-end, etc.) is most in the spotlight for improving power efficiency?

Le Fèvre: The entire power range to an extent, but with bricks now reaching 1kW power levels, clearly this is the area that requires the most attention to avoid a power module becoming a toaster. High-performance computing equipment and routers are integrating more strategic processors and some boards will reach 3-kW levels, which will mean the use of efficient intermediate bus converters and as potentially as many as 80 point-of-load (PoL) regulators. For boards populated with high-power PoL bricks ranging from 3 to 240 A, all of these components will need to be highly energy efficient.

Musavi: Certainly, low efficiency conversion rates become more impactful as the power goes up.  For example, the power loss for a 700-W converter running at 89% efficiency looks very different than a 10W converter running at 89%. However, improving power efficiency is not an option anymore, it is a must, and we are seeing the demand for improvements across the board. Demands for improved cost-effectiveness, higher power density, and effective power management solutions are driving us to develop more efficient power converters, from low-power external adapters, to high-density intermediate bus bricks, in order to meet customer demand.

Bocock: Two categories are certainly in the spotlight at the moment. First, there is a lot of attention for sub 500-W convection-cooled products. Cooling a power supply is always much easier when a forced airflow from a fan is available, but for today’s space-constrained designs the use of convection cooling is increasingly a popular choice. The other area relates to external power supplies and the increasing focus on energy efficiency, and no load consumption as required by Energy Star Level VI and EU CoC legislation. Market forces are greatly influenced by such initiatives.

Tuite: Are distributed power architectures or other concepts such as IBA, PoL, and PoE driving more attention to efficient dc-dc conversion, or are industry alliances such as Emerge also responsible?

Musavi: I believe that a number of macro-factors are driving more attention on the need for efficient dc/dc conversion.  According to the Ericsson Mobility Report, annual IP traffic will reach 7.7 zettabytes by the end of 2017, up from 2.6 zettabytes in 2012. Video communications, cloud-based services, and the interconnection of physical objects (the Internet of Things) are the primary drivers of this growth. This is placing immense demands on data network power systems, thus driving great awareness on the need for efficient power conversion from corporations and governments alike. The distributed power architecture, IBA, PoL, and digital control are a few of the tools power designers have created over the past few years to try to address these challenges.

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Le Fèvre: In ac-dc, industry bodies such as Energy Star have establishing rules and thresholds, whereas in dc-dc, energy efficiency has been inherent in their evolution, driven by market demand. While this has been the situation for many years, as segments such as data centers consider dc distribution, then organizations such as Emerge could drive dc-dc energy improvements in this specific area. But it is unclear that specific actions will trickle down to a single PoL.

(Gary Bocock did not comment because XP Power is not active in this area.)

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