While upgrading the grid and repowering the data center are grand, sweeping issues, it’s important not to lose sight of basics. For an international perspective, we discussed future efficiency gains and advances in digital power with senior executives at European power supply companies: Jeff Schnabel, VP of marketing at CUI Inc.; Don Knowles, VP of engineering at N2Power; and Gary Bocock, technical director at XP Power.
Don Tuite: The efficiency of medium size ac-dc power supplies is now firmly in the mid-90% area. And while these efficiencies are impressive, the vast number of power supplies shipped each year means even small efficiency gains have a significant effect on our power consumption. Where do manufacturers go from here, and what limitations are in place?
Jeff Schnabel: I believe that tomorrow’s innovations will occur through the discovery and implementation of new power topologies and materials such as gallium nitride (GaN) and silicon carbide. As an example, CUI’s [dc-dc] Solus Power Topology currently is able to reduce switching turn-on losses by 75% and switching turn-off losses by 99% on the control FET when compared to a conventional buck converter. Our testing shows that it holds similar advantages when implemented in ac-dc, ultimately allowing for increased efficiency and reduced package size.
DT: How much of an improvement will we see during 2013, and what’s likely in five years?
GB: The latest designs include quasi-resonant PFC stages, resonant power converters, and synchronous rectification to minimize the switching and other losses throughout the power chain. New products reach efficiencies of 95% at high line input voltages and maintain efficiencies above 92% at minimum input voltage. The development of components and techniques will see this improve.
DT: What are the biggest challenges faced in improving system efficiency through power supplies?
JS: The biggest challenge resides in the fundamental nature of switching conversion and the associated switching losses at turn-on and turn-off. The never-ending challenge of power supply designers will be to minimize these losses, whether through topology breakthroughs or component-level improvements.
DT: What are the key factors OEMs should specify if they are to improve the system efficiency through the power supply?
JS: Because real-world systems typically do not operate at a steady state, OEMs should examine the power supply’s complete efficiency curve and ensure it is optimized to their application’s loading profile. By doing so, they can best match the power supply to their system’s needs.