PFI-TT: Development of Single-Stage Power Modules for Modular Medium-Voltage Electric Vehicle Fast Chargers

The broader impact/commercial potential of this PFI project is to provide an electric vehicle charger that is at least 10 times smaller than existing EV charging systems and wastes half as much power during the charging process. This advanced is based on the proposed solid-state transformer (SST) technology, which makes use of a high frequency magnetics to shrink the system size and improve efficiency. The SST connects directly to the medium voltage distribution system, eliminating bulky step-down transformers, and eliminating power conversion stages. A smaller, more efficient EV charger translates into cheaper system installation, higher revenue, and better site utilization for charging station owners, and cheaper and faster charging for the EV owners. The same technology can serve other applications where large DC loads are present, including the data centers, which already make up 1.8% of total US power consumption. The proposed project will advance technologies developed under the FREEDM ERC, by solving a number of important challenges in the area of medium voltage power conversion. We will prove that our recently discovered, provisional patent protected, single stage power converter can reduce system costs and improve system efficiency. The team will analytically derive the conditions that allow for switching device soft-switching transitions that result in minimal system losses. We will develop analytical models to determine the optimal switching trajectories that consider phase shift, switching frequency and non-linear saturable inductor elements as independent variables. With an analytical representation of the optimal modulation schemes for the proposed controller, the team will develop a design space exploration tool to systematically trade off converter design parameters against multiple performance criteria, namely cost, efficiency, power density and reliability.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.