ECE ILLINOIS graduate students win best presentation awards at 2018 IEEE APEC

ECE ILLINOIS graduate students , Nathan Andrew Pallo, Zitao Liao, and Thomas Peter Foulkes, advised by ECE ILLINOIS Adjunct Associate Professor Robert Pilawa-Podgurski, won best presentation awards at the 2018 IEEE Applied Power Electronics Conference (APEC). IEEE APEC is the world's leading conference in the field of power electronics. 

“I’m incredibly excited that my graduate students’ hard work was recognized by experts in our field with these awards,” said Pilawa-Podgurski. “Receiving a best presentation award at APEC is a significant achievement for any power electronics engineer. Andrew, Nathan, Zitao, Tom, and co-authors worked very hard in the lab to achieve excellent research results and were able to communicate those results effectively to an audience of peer experts, as evident by these recognitions. The fact that our group received four such recognitions for a second year in a row was certainly exciting and encourages us to continue exploring innovative solutions to problems in the area of power and energy, with large impact on society. We are also looking forward to continue working with our outstanding sponsors on these topics, which included NASA, Texas Instruments, NSF, POETS, and CRRC.”

Stillwell’s research involved the development of a 1 kV bi-directional SC-DC converter. “High voltage systems for electrified transportation require solutions that offer low loss and packaged volume while not compromising on low cost. To achieve this, I implemented a multi-level converter with 650 V GaN FETs and low profile magnetics. In addition, my work proposed design rules to achieve these performance requirements and demonstrated this functionality with a hardware prototype.”   

Liao investigated the design and control of an ultra-compact, single-phase power factor correction (PFC) converter. “Every grid-connected single-phase AC-to-DC system such as a data center power delivery system or an electric vehicle charger needs a PFC circuit to ensure a low-harmonic, high power factor grid current to satisfy certain power quality regulations. Though high power density and high efficiency are desirable in these applications, conventional solutions based on boost converters suffer from larger inductor volumes and high switching loss. By leveraging digital control, advanced multilevel circuits, and state-of-the-art GaN FETs, our 1.5 kW PFC prototype achieved 490 w/in^3 power density and 99.1% peak efficiency, which demonstrates significant improvements compared to any existing work reported by academic or industrial groups.”

Pallo was recognized for presenting the results of NASA and NSF POETS funded projects at Illinois, sharing the honors with contributors from both his group at Illinois, as well as collaborators from Stanford University. "NASA predicts that more-electric aircraft could offer 80% lower NOx emissions, 60% less fuel consumption, and 71 dB less noise than modern commercial aircraft.  Realizing these benefits requires simultaneous improvements in the efficiency and package density for converters and electric machines. Our team at Illinois has been developing state of the art inverter designs with simultaneously high power efficiency and power density - both necessary research that will someday lead to much cleaner air travel. These awards are a testament to the hard work and ingenuity from everyone on our team, and I am thankful for the opportunity work with such talent."

Foulkes, an NSF Graduate Research Fellow and CSL affiliate, proposed a method for quantifying a non-linear loss behavior for gallium-nitride (GaN) transistors.  “Designing and optimizing ultra-efficient converters requires detailed knowledge of the behavior and parasitic parameters for both active and passive components. While new wide bandgap transistors are a key enabling technology for next-generation power electronics, the early acceptance of gallium-nitride (GaN) switches has been plagued by detrimental dynamic on-state resistance effects. This non-linear, second-order phenomenon for GaN devices is characterized by an increase in on-state resistance with increasing voltage stress.  Based on measurements from a large survey of commercial GaN transistors, our team at Illinois has proposed metrics that can help engineers facilitate an equitable comparison of different GaN device technologies during design, enable manufacturing qualification, and provide a benchmark to catalyze improvement for the next generation of GaN device development.”

Foulkes, who is co-advised by Prof. Pilawa-Podgurski and Mechanical Science and Engineering Assistant Professor Nenad Miljkovic, is grateful for financial support of his research in part from the National Science Foundation Graduate Research Fellowship Program, the POETS NSF Engineering Research Center, and the NASA Fixed Wing research program.