High enthusiasm for low power | ECE | Virginia Tech


High enthusiasm for low power

Qiang Li in a CPES lab

Qiang Li

Qiang Li likes building devices that boost performance or shrink size by remarkable amounts. As a graduate student, he was featured in a 2010 article showing a miniature DC-DC converter that was 51 percent of the size of then-current technology. This spring, Cheryl Martin, chief of ARPA-E highlighted a device he and Fred Lee developed that is 10 times smaller than current technology.

Now an assistant professor in his first year of teaching, Li not only appreciates being part of "one of the best power electronics research groups in the country," but also likes teaching. "I very much enjoy interacting with undergraduate students," he says.

"I'm a Hokie," he adds. "I enjoy working here. All the researchers at CPES are passionate about what they are doing. That's why they do such a great job."

Industry partnerships speed commercialization

CPES has very close relationships with industry, which helps to fuel the group's passion, according to Li. "CPES has a unique and wonderful industry partnership program," he says. He appreciates how, by working with its partners, CPES is able to conduct fundamental research that helps the entire industry take the next steps. "Instead of waiting 10-20 years to see our efforts make a difference, some of our technologies get commercialized in three to five years. We can see the immediate benefits for society from the work we do."

Power electronics advances make many technologies more affordable and sometimes economically feasible for the first time. "We have been very successful with developing technologies (voltage regulators, advanced control scheme, high frequency magnetic components and high density integration) for telecommunications and computing applications," Li says. "Now we are moving into photovoltaic and battery management." The target, he says, is to increase efficiency and save energy.

The CPES laboratories also house a DC nano-grid, which has a battery system, a photovoltaic array, a wind turbine and LED lighting. "We can combine everything together and build the system for the future. Imagine what power electronics can do with PV and batteries."

Improving efficiency with a smaller chip

Li's personal research focuses on low-power, high-frequency applications. "We are trying to push high power density through high frequency," he explains. He points to a 2006 prototype that is 500 kHz converter, then to the latest voltageregulator designed for a $1.56 million ARPA-E project. "This prototype is 5MHz-10 times higher."

The CPES GaN 3D chip next to a larger chip

The CPES GaN 3D chip (bottom) developed for ARPA-E's power-supply-on-a-chip project is 10 times smaller than today's commercial technology.

Li works on the ARPA-E: power-supply-on-a-chip project with Lee, who is principal investigator. Their 3D chip uses semiconductors of gallium nitride on silicon and a high-frequency soft magnetic material. In addition to increased efficiency, the chip is 10 times smaller than commercial voltage regulators. Today voltage regulators occupy 30 percent of a motherboard's footprint. The new chip is expected to free up to 90 percent of voltage regulator space.

The ARPA-E project was initially a two-year project, he explains. Because of the success of the CPES design, however, an additional year of funding was extended to move the technology toward commercialization. CPES is working with Enpirion, International Rectifier and the University of Delaware on the project.

Li works with CPES industry partners in its Power Management mini-consortium on improved power management technology for telecommunications, computing, PV, battery and LED power management. "Our objective is to increase the efficiency, reduce the size and boost the intelligence of power electronics devices." Achieving these goals involves packaging and circuit design, magnetics design, and modeling. He enjoys each aspect of the problem.

When Li first started studying power electronics, he had no idea whether or not he would enjoy the field. "I like to think that power electronics chose me," he says. "In high school when I was choosing my major for college, I knew nothingabout power electronics. But, I knew I liked to build hardware. I knew I wanted to be in a field where I could build something." He also liked the idea of electronics and decided that power sounded like it could be interesting. "I had no idea what I was getting into, but it turns out I like it very much."

Spotlight on New Faculty Members

Qiang Li joined ECE in August 2012 as an assistant professor. His research interests involve high-density electronics packaging and integration, high-frequency magnetic components, high-frequency power conversion,distributed power systems, and renewable energy. Li earned his BSEE and MSEE from Zhejiang University in China in 2003 and 2006 respectively. He earned his Ph.D. from Virginia Tech in 2011.

Boosting Electrical Efficiency

The Center for Power Electronics Systems (CPES) runs a $4 to $5 million-a-year researcheffort dedicated to changing the way electricity is used through dramatic improvement in power electronics systems.

From 1998 to 2008, CPES was a National Science Foundation Engineering Research Center(ERC). A collaboration of five universities and many industrial firms, the CPES ERC was the largest-ever collaboration of power electronics researchers. During the ERC period, CPES developed the IPEM, a standardized off-the-shelf module that is today enabling more applications to achieve performance and reliability increases with lower cost and greater energy efficiency.

Today, the CPES Industry Consortium, with 81 industry members and three mini-consortiums for focused research in Power Management, High Density Integration, and Renewable Energy and Nanogrids, along with various sponsored research projects, is one of the largest university-based power electronics centers in the country. Fred Lee serves as founding director and Dushan Boroyevich is co-director.