Researchers at the Oak Ridge National Laboratory (ORNL) have demonstrated a 120-kilowatt wireless charging system for vehicles—providing six times the power of previous ORNL technology and a big step toward charging times that rival the speed and convenience of a gas station fill-up.
The wireless system transfers 120 kilowatts of power with 97 percent efficiency, which is comparable to conventional, wired high-power fast chargers. In the laboratory demonstration, power was transferred across a 6 inch (15 cm) air gap between two magnetic coils and charged a battery pack. This demonstration advances the Department of Energy’s (DOE) extreme fast-charging goal to develop a system that delivers 350 kilowatts to 400 kilowatts and reduces the charging time for electric vehicles to 15 minutes or less.
»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«, said project lead Veda Galigekere of ORNL’s Power Electronics and Electric Machinery Group. To achieve 120 kilowatts, the ORNL team created a new coil design co-optimized with the latest silicon carbide power electronic devices for a lightweight, compact system.
ORNL researchers will explore innovations to increase power transfer level to 200 and eventually 350 kilowatts, while refining dynamic wireless charging technology. A dynamic system enables the automatic charging of electric vehicles using wireless charging pads installed under roadways. Higher power charging systems are needed to minimize the cost and complexity of dynamic charging. »The goal is dynamic charging at highway speeds«, Galigekere said.