Solid state transformers targets microgrid charging of electric cars
The three year, $7m project from the US Department of energy includes ar maker GM as well as DTE Energy, NextEnergy and CPES Virginia Tech.
The proposed XFC design is expected to offer grid-to-vehicle efficiency up to 96.5 percent, four times less weight and half the size of conventional DC fast chargers (DCFC), as well as a high voltage direct current (HVDC) port to connect to energy storage and renewable energy microgrids.
The proect will be led by Delta’s automotive division, based in the greater Detroit area (Livonia, MI), and researchers from the Delta Power Electronics Laboratory (DPEL) in North Carolina’s Research Triangle Park.
“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 using 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 solid state power cell topology directly uses medium voltage alternating current (MVAC) at 4.8kV or 13.2kV, 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) MOSFET device, the proposed SST enables a 3.5 percent improvement in grid-to-vehicle efficiency to industry-leading levels up to 96.5 percent, a 50 percent reduction in equipment footprint, and four times less weight than today’s DCFC EV chargers.
The 400kW XFC prototype is expected to be ready in 2020 aims to provide 50% of a vehicle’s charge in 10 minutes.
Early data and results from the program will provide car makers, technology providers, cities and utilities with a greater 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.