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US DoE backs Delta EV fast charging research

Steve Rogerson
September 5, 2018

Taiwanese company Delta Electronics is working with the US Department of Energy (DoE) to develop technology that can give an electric vehicle a 290km range from a ten-minute charge. It will also use renewable energy to reduce demand on the power grid.
The company has started work on a research programme, with 50 per cent cost-share by the DoE, to develop a solid-state transformer (SST)-based fast EV charger (XFC) with capacity up to 400kW. 
Moreover, the proposed design is expected to offer grid-to-vehicle efficiency up to 96.5 per cent, four times less weight and half the size of conventional DC fast EV chargers, as well as a high-voltage DC port to use energy storage and renewable energy systems, reducing demand on the power grid.
This initiative will be supported and led by a development team based out of Delta's automotive division in Detroit and researchers from the Delta Power Electronics Laboratory in North Carolina's Research Triangle Park.
Delta's partners for this three-year, US$7m project, include General Motors, DTE Energy, CPES Virginia Tech, NextEnergy, 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 MS Huang, president of Delta Electronics in the Americas. "By utilising 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 AC at 4.8 or 13.2kV, eliminating conventional line frequency transformer technology, which converts low voltage AC to DC to charge the high-voltage battery in an EV. Combined with a silicon carbide (SiC) mosfet device, the SST could enable a 3.5 per cent improvement in grid-to-vehicle efficiency to levels up to 96.5 per cent, a 50 per cent reduction in equipment footprint, and four times less weight than today's DC fast EV chargers.
Moreover, the 400kW XFC prototype, which is expected to be ready in 2020, will have a power level to improve charging speed on long-range EVs. With this technology, EV drivers will need close to ten minutes to achieve an additional 50 per cent of vehicle range on their vehicle. For example, a 580km EV could achieve a 290km range in approximately ten minutes of charging.
Early data and results from the programme will arm automotive manufacturers, technology providers, cities and utilities with a better understanding of how fast-charging will impact demand response efforts within specific circuits. The project will also provide insight into how renewable generation can be integrated to avoid infrastructure strain on the power grid associated with the wide deployment of XFCs.