The US Department of Energy's Oak Ridge National Laboratory (ORNL) built and demonstrated a 20 kW wireless charging system in April 2016, reported capable of operating at 90 percent efficiency. Now ORNL has taken another giant leap towards meeting the DofE's goal of making electric vehicles as practical and affordable as gas guzzlers by 2022 with the creation of a 120 kW wireless charging prototype.

ORNL's latest wireless charging system takes energy from the grid, converts it to high-frequency AC before transferring power across a 6-inch air gap to a secondary coil, where it's converted for storage in a battery pack. Though the system is built around a brand new coil design, it remains lightweight and compact.

"It was important to maintain the same or smaller footprint as the previous demonstration to encourage commercial adoption," said project lead Veda Galigeker. "We used finite element and circuit analyses to develop a novel co-optimization methodology, solving the issues of coil design while ensuring the system doesn't heat up or pose any safety issues, and that any loss of power during the transfer is minimal."

In its laboratory demo, the project team managed to transfer 120 kW of power with 97 percent efficiency, which is said to be comparable to plug-in fast chargers in operation today. But the researchers are not stopping there. They plan to look for ways to increase power transfer to 200 kW and beyond, eventually delivering 350 kW systems capable of charging an electric vehicle in 15 minutes or less.

There's also talk of developing dynamic charging systems, where wireless charging pads are installed under road surfaces that will allow for top-ups at highway speeds.

Source: ORNL

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