High-frequency, three-port transformers demonstrate ability to improve solar power

Incorporating high-frequency, three-port transformers into commercial-scale photovoltaic (PV) power installations can increase power density by 10 times or more than traditional technologies, researchers at the National Energy Technology Laboratory (NETL) recently discovered.

Eaton Corp, North Carolina State University, Carnegie Mellon University, and NASA’s Glenn Research Center have partnered on the three-port transformer research project. The project’s goal is to counter cloud cover, weather patterns, and other factors that impact the reliability of PV power.

Three-port transformers eliminate the need to connect each energy source to an electric grid through an individual alternating current-coupled transformer. Rather, three-port transformers enable PV energy sources to connect directly to the same same transformers as energy storage devices.

“The design of the transformers can vary, but NETL researchers and their partners have reconfigured the windings in a scheme that maximizes power flow and enhances flexibility,” according to a Department of Energy (DoE) release. “The transformers are also designed to transfer electrical energy at a higher frequency — 10-50 kilohertz versus 60 hertz — which makes them smaller and increases power density substantially.”

NETL researchers have discovered that incorporating high-frequency, three-port transformers into the direct current side of PV and energy storage can foster greater efficiency, power density, reliability, and lifetime savings.

“Prototype converters up to 10 kilowatts (kW) were built using this technology and demonstrated with successful power flow, increased power density and efficiencies approaching 99 percent versus traditional efficiencies of about 94 percent,” DoE stated. “Prototype converters of 30kW and 50kW are being built and tested for demonstration in ongoing research under the project, and system-level simulations demonstrated the potential for successful operation of full-scale 1-megawatt combined solar/energy storage inverter architecture for utility-scale grid-tie inverter applications.

The project is funded by the Sunshot National Laboratory Multi-Year Partnership (SUNLaMP) program, which is managed by DoE.