The Inevitable Direction of the Power Conversion Industry
Changes are on the horizon for the power supply industry as lower-end solutions start catching up to the technology pace set by high-end solutions. The catalyst for this transition may be the regulatory environment, which speeds the mating of the market requirements with appropriate leading-edge technology. However, the semiconductor industry will play a major role as a key technology provider and enabler.
In the last few years, power supply has evolved from an afterthought to a subsystem that is critical to meeting system-level performance requirements. In the same period, there have been dramatic reductions in the cost of power supplies. In light of these conflicting developments, it is time to take a fresh look at industry trends.
Power supply solutions in the market today span a wide spectrum of technologies. The high end is exemplified by the ultra-slick dc-dc converters that pack significant power punch in small packages. The low end is characterized by the low-power chargers (wall-warts) that employ linear regulators with line-frequency transformers. Even the switch-mode versions on the low end are clearly low tech.
The reasons for such a disproportionate technology spread are not hard to fathom. First and foremost: economics. If performance metrics — such as power density, efficiency, low EMI, light weight and low harmonic generation — are not emphasized by the end user, the lowest cost alternative wins. Second, power supplies have been an afterthought in any system design with little upfront technology investment. Because of severe time constraints, most power supply designs have little time to incorporate revolutionary ideas — particularly since current market solutions work and are accepted by everyone, including end consumers.
Third, there have been no regulatory pressures driving the innovation rate in power supply design. Finally, the power supply field is unique in that it is truly multidisciplinary. No other “specialized” engineering field requires expertise in so many areas — analog circuits, magnetics, control theory, packaging, thermal management and device physics. With so many disciplines, it is more difficult to envision breakthrough technology impacting the field.
Linear extrapolation from the above may indicate that the power supply world will continue to progress forward in the same stutter-step fashion. However, reasons for optimism also can be found by looking at recent trends.
The economic context can be changed by emphasizing the total cost of ownership and identifying some of the hidden costs of low-tech approaches. For example, in linear power supplies for low-power chargers, rising material costs are already tilting the economics in favor of switching solutions. However, if you add in the lifetime energy-cost differences in standby and active modes, switching solutions emerge as the clear winner.
Consumer expectations are indicating to OEMs that power supplies in many applications are at the breaking point. Take battery-life expectations for notebook computers and cell phones: How many consumers would like a better power solution?
Regulatory pressures have recently emerged. The U.S. EPA's Energy Star, China's CECP, the European Union's Code of Conduct and the Australian Greenhouse Office's NAEEEP program recently collaborated to roll out a unified certification program and common test procedures to simplify cross-certification. These age ncies have set requirements for both standby- and active-mode efficiencies, which are expected to raise the performance standards of power supplies significantly.
The multidisciplinary breadth of power electronics also presents the opportunity for parallel advances in one of the disciplines to rub off on power technology. In today's environment, the obvious candidate for driving this growth is semiconductor technology. Already, component advances in power discretes are having a tremendous impact on the performance of power supplies. Analog IC technologies with higher integration levels and smaller geometries also are changing the way power supplies are designed.
Advancing semiconductor technology can deliver increasing power density at a reasonable cost, which can solve the emerging challenges faced by power supply designers across the spectrum of applications.
Dhaval Dalal is a systems engineering director for power supplies at ON Semiconductor, where he defines the strategy, road maps and technical content of many products for power supply applications. Dalal holds a B.Tech.(EE) from IIT-Bombay, an MSEE from Virginia Tech and a master's in management of technology from NTU. He has published and presented more than 20 technical articles, papers and invited talks.