Delta, a global provider of power and thermal management solutions, announced it has begun work on a research program, with 50% cost share by the U.S. Department of Energy (DOE), to develop a solid-state transformer (SST)-based extreme fast EV charger (XFC) with capacity up to 400 kW that's intended to provide capable EVs a 180-mile range with less than 10 minutes of charging. The proposed XFC design is expected to offer grid-to-vehicle efficiency up to 96.5%, four times less weight and half the size of conventional DC fast EV chargers (DCFC), as well as a high voltage direct current (HVDC) port to use energy storage and renewable energy systems, minimizing demand on the power grid.

The initiative is being supported and led by a program development team consisting of industry experts based out of Delta's automotive division, located in the greater Detroit area (Livonia, MI), and researchers from the Delta Power Electronics Laboratory (DPEL), located in North Carolina's Research Triangle Park. Delta's partners for this three-year, $7 million project include General Motors LLC, DTE Energy, Center for Power Electronics Systems (CPES) Virginia Tech, NextEnergy, the Michigan Agency for Energy's Energy Office, and the City of Detroit's Office of Sustainability.

"We're thrilled to lead such an important project and have a stellar team of researchers and partners in place that are more than ready to take on the challenge of setting a new standard for EV fast charging," said M.S. Huang, President of Delta Electronics (Americas). "By utilizing solid-state transformer technology, we have the opportunity to create unprecedented charging speed and convenience that will ultimately help support the DOE's strategic goal of increasing EV adoption across the nation."

The novel SST power cell topology directly uses medium voltage alternating current (MVAC) at 4.8 kV or 13.2 kV, eliminating conventional line frequency transformer (LFT) technology, which converts low voltage alternating current to a direct current (DC) to charge the high voltage battery in an EV. Combined with a new silicon carbide (SiC) metal oxide semiconductor field-effect transistor (MOSFET) device, the proposed SST enables a 3.5% improvement in grid-to-vehicle efficiency to levels up to 96.5%, a 50% reduction in equipment footprint, and four times less weight than today's DCFC EV chargers. In addition, the 400 kW XFC prototype, which is expected to be ready in 2020, will reportedly have a power level enabling 3C charging speed on tomorrow's long-range EVs. With this technology, Delta says that EV drivers will need close to 10 minutes to achieve an additional 50% of vehicle range on their vehicle.

To find out more about the topic of extreme fast charging and the technical gaps to implementing it at the battery, vehicle, and infrastructure levels, read the report, Enabling Extreme Fast Charging: A Technology Gap Assessment. The report was compiled by researchers at Idaho National Laboratory, Argonne National Laboratory, and the National Renewable Energy Laboratory.