Researchers drive rectifier efficiency to 99%

MUNICH, Germany — A research team at the Swiss Federal Institute of Zurich (ETH Zurich) has developed a rectifier for computer power supplies that operates near the theoretical maximum efficiency.

The team around Juergen Biela found that there is a trade-off between size and efficiency in rectifier diodes and other semiconductor components used in power supplies: The smaller the size of the component the worse gets its efficiency. Optimizing a system for small physical volume affects its efficiency. This effect limits the ability to further miniaturize rectifiers for power supplies, Biela said.

With his team he found a method to optimize these parameters for efficiency and achieved a rectifier efficiency of 99.2 percent at a power level of 1.6kW and a power supply volume of 1.1 liter. "Given today's materials, this efficiency is certainly the optimum", Biela said.

The team designed rectifier prototypes optimized for efficiency at a given volume. The devices are currently under test at a major semiconductor vendor, the group said in a press statement. The next target for the research group will be chip-level dc/dc converters typically integrated on microprocessors, SoCs, and RAM chips.

In order to measure the efficiency the team also had to develop a measurement technology offering an accuracy of 0.05 percent. The modeling and optimization technique developed by the Zurich team can also be used for novel materials such as silicon carbide, the group said.