Professor hopes to revolutionize power transformers

For more than 100 years, the technology behind electric grids has stayed largely the same. Power plants generate alternating current (AC) that transformers "step up" for transmission over long distances and then "step down" for use in our homes, offices and industrial settings.

As the world reduces the use of fossil fuels and renewable energy sources become more prevalent, energy storage will become increasingly important for consistent delivery, and batteries store electricity as direct current (DC).

While more green energy such as solar and wind power are key to fighting climate change, there are obviously times when skies are cloudy, dark or calm. The solution is to store extra power during peak generation and then distribute that energy into the grid as needed later.

The advent of wide-band gap power semiconductor devices led to smaller, lighter solid-state transformers (SSTs). They are based on conventional AC-DC and DC-DC bidirectional converters, however, so they have low efficiency, poor reliability and higher cost because of multiple stages that involve many power devices, slow transient response and input filters that are as large and bulky as the transformers they aim to eliminate.

Assistant Professor Pritam Das — a Department of Electrical and Computer Engineering faculty member at Binghamton University's Thomas J. Watson College of Engineering and Applied Science — has researched various aspects of better integrating bidirectional AC-DC and DC-DC converters with high-frequency galvanic isolation with a long-term goal of significantly advancing SST technology.

"Energy storage as electrochemical energy in the form of lithium-ion batteries or redox flow batteries is going to be one of the major ways of mitigating the intermittency in these types of renewable energy-based power systems," Das said.

A five-year, $537,959 National Science Foundation CAREER Award announced in April will give Das the funding to rethink how SSTs are realized and function. A CAREER grant supports early career faculty who have the potential to serve as academic role models in research and education.

"These new SSTs will have 25% fewer components compared to what is used now," he said. "They also will be 40% more power dense, 5% more efficient, five to six times faster for transient response, 30% cheaper and compliant with standards like IEEE 1547 [which regulates how utility power systems and distributed energy resources such as wind and solar generators are connected]. With these advantages, the new SSTs contribute to the decarbonization of the electrical power grid for a more sustainable future."

Applications for battery energy storage systems as part of the power grid are expected to grow above 4,000 terawatt-hours in the U.S. by 2030, and using the new SSTs from this research for grid integration of energy-storage systems alone would reduce the losses during power conversion for energy storage by about 400 gigawatt-hours.

Because they take up less space, the new SSTs will be key to public transport in urban areas using electric buses, electrical vertical-takeoff-and-landing (VTOL) taxis and other vehicles, data centers and other applications where what Das calls "good old transformers" are impossible to install.

"You have the benefits of installing electric vehicle charging systems easily at congested locations, where hooking up a line frequency transformer and maintaining it is a big hassle," he said.

Das is grateful to his now-graduated students for their help in his research so far: Sunil Dube, PhD ’22, who won the Distinguished Dissertation Award; and Watson post-doctoral research fellows Kalyan Yenduri and Ramu Nair.

To ensure more people will be trained in state-of-the-art power electronics based on his research on SSTs, Das’ CAREER Award includes a partnership with SUNY Broome Community College and its Engineering Science Department to recruit students and professionals to the field, especially underrepresented minorities and women. He knows that more opportunities are ahead for those who can answer climate-change challenges.

"For the grant, I outlined my research pathway for five years, and then at least 10 years beyond those first five years," he said. "This opens up more research and possibilities for more funding in the future from different agencies. I already have had some support from New York state and the U.S. Department of Energy, also while working on demonstration and applied projects with industry. I hope that this research will result in more investments in the work that we are doing here and also will attract commercialization partners that incorporate our SST technology into their products deployed in the field."