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nanotimes News in Brief

11-05 :: May/June 2011

Solar Inverter // German Fraunhofer Researcher Achieved a World Record for Inverters with HERIC®

Topology

and increase the efficiency from 96 to 98%. The HERIC®

A -topology makes it possible to achieve a world-record efficiency of more than 99%.

“It was a matter of minutes,” Dr. Heribert Schmidt remembers the day in spring of 2002. To find op- portunities for improvement, he had often pondered about the switching plan of an inverter while in his office at the Fraunhofer Institute for Solar Energy Systems ISE in Freiburg, Germany. A sudden flash of inspiration – and a solution that was ingeniously simple came to his mind. He immediately went to get an inverter from the laboratory, laid a few new strips and installed two additional semiconductor switches. “Then it required only a little bit of work on the controls - and we already had the proof!” This is how the electrical engineer, who holds a doctorate in electrical engineering, described the revolutiona- ry step in brief: the losses could be halved and the degree of effectiveness could be increased from 96 to 98 percent.

Heribert Schmidt knew: A large portion of the losses are caused by the return of current between the output inductor and the input capacitor. The questi- on therefore was how to prevent this. “That‘s easy,” said Heribert Schmidt after a sudden inspiration: “If I

switching trick makes it possible to cut the losses of a series-production inverter in half

decouple the capacitor and the inductors completely from each other at certain intervals, then it is impos- sible for a return current to flow, and electro-magne- tic disturbances cannot occur at the input as a result of voltage spikes.”

He immediately had his invention patented as HE- RIC®

topology and began to develop a new series of

devices with the SUNWAYS company in Konstanz, Germany. Experts were astonished, and awards and recognition followed quickly: “By far the best device in this performance category.” In the meantime, an encompassing patent has been awarded to the basic idea and the Fraunhofer-Gesellschaft is in negotia- tions with additional licensees.

The director of the institute, Prof. Eicke Weber, emphasizes, “In 2009, a world record of more than 99 percent efficiency was set for inverters.” Heribert Schmidt – who has been with the Fraunhofer Insti- tute for Solar Energy Systems ISE since 1988 – is an experienced inventor with more than 20 awarded patents. The HERIC®

patent provided the institute

with lucrative licensing agreements – and Heribert Schmidt with the Fraunhofer Prize.

http://www.fraunhofer.de/en/Images/Fraunhofer-Re-

search-News-special%20issue-may2011_tcm63-91211. pdf