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 (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."