Power Electronics

Key Power Trends for the Next Five Years

Based on data presented by five end-user companies (IBM, Nortel Networks, Cisco Systems, Dell and Intel), input collected from five power-supply manufacturers (Power-One, Celestica Power Systems, Tyco Electronics, Artesyn Technologies and Primarion), and contributions from component suppliers, market analysts and other members at its February workshop in Miami, Power Supply Manufacturers Association (PSMA) has released a 380-page report focusing on the needs of the users. The report also identifies key power-conversion trends over the next five years.

To identify key trends and technical challenges in the power-supply arena, the latest PSMA report has broken down the study into three main categories: ac-dc front-end supplies rated up to 1000 W; isolated dc-dc converters or bricks up to 100 W; and nonisolated point-of-load (POL) dc-dc converters handling up to 200 W. According to the report, these categories were selected because they represent the largest growth market. In the 1000-W ac-dc arena, the five-year forecast metrics indicate the cost of the supply will drop from $0.10/W to $0.20/W at present to $0.08/W to $0.14/W in 2008, while density will shrink from current 3-10 W/in3 to 10-25 W/in3 in 2008. Likewise, efficiency will improve by a few percent to achieve 85% to 92% in the next five years. Furthermore, because of emission restrictions, the supply's PFC section would use switching frequency at or below 140 kHz. However, it could reach 400 kHz if better semiconductors, such as silicon carbide (SiC) rectifiers, become cost effective by 2008. Additionally, the PFC stage will see higher integration, as well as a move toward digital control. Plus, as power density continues to rise, these products will make more use of thermal bus schemes.

Regarding isolated 100-W bricks, the cost structure will drop to $0.20/W to $0.45/W in 2008, and density will soar from today's 75 W/in3 to 100 W/in3, with a marginal improvement in efficiency. From current 85% to 93%, these bricks will offer 90% to 95% efficiency with nominal input voltage range remaining the same. However, the output voltage will go down to 0.8 V, while the dc output current will increase to 100 A. Additionally, the unit's reliability will almost double to 4 Mh. The report indicated that the active clamp forward converter with synchronous rectifiers is the predominant topology now and will continue for some time. Other new topologies are also in the works, including some with digital control loops. Furthermore, these products will see a significant shift toward chip-scale packages. Packaging has played a key role in enhancing the power density and efficiency of dc-dc converters. This trend will continue as designers look for further improvements through expanded usage of integrated passives and multichip modules (MCMs).

On the nonisolated front, the cost of dc-dc converters will fall from today's $0.15/A to $1.00/A to $0.10/A to $0.50/A in 2008. While density will improve from 50 A/in3 to 75 A/in3, the efficiency gain is projected to be marginal. Because these converters will have to deliver in excess of 100 A at low voltages, they will employ multiphase topology with up to 8 phases and 30 A to 35 A/phase. The input range can be as wide as 2.5 V to 12 V, while the output voltage could be anywhere between 0.5 V to 2.5 V. Also, the report indicated that digital control is the wave of the future.

While this five-year technology roadmap provides a glimpse of forthcoming enhancements in the power supply arena, it also sends an alert signal. Aside from losing its manufacturing base, the United States is also losing its know-how in power electronics. To maintain the U.S. design and manufacturing base, a paradigm shift is needed in the way power systems are designed and built, as one industry pundit commented.

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