The Oak Ridge National Laboratory of the US Department of Energy has developed a revolutionary new 120-kilowatt wireless charging system for vehicles that not only offers six times more power than any previous ORNL technology but also advances the DOE’s goal to develop a system that could rival the speed and convenience of filling up at a gas station.
Developed by ORNL researchers, the new wireless vehicle charging system was able to transfer 120 kilowatts of power across a six-inch air gap between two magnetic coils with 97 percent efficiency to charge a battery pack in a laboratory demonstration.
The researchers had earlier developed the world's first 20-kilowatt wireless charging system, which is now being modified for applications such as commercial delivery trucks.
Project lead Veda Galigekere of ORNL's Power Electronics and Electric Machinery Group emphasised the need to maintain a similar or smaller footprint as the previous demonstration to encourage commercial adoption of the wireless charging technology.
He explained that the researchers used finite element and circuit analyses to develop a novel co-optimisation methodology, solving the issues of coil design while ensuring the system didn’t heat up or pose any safety issues, and also minimised any loss of power during the transfer.
For the latest 120-kilowatt vehicle charging system, the researchers created a new coil design co-optimised with the latest silicon carbide power electronic devices to retain the lightweight and compact characteristics.
Power from the grid is converted to high-frequency alternating current, which generates a magnetic field that transfers power across a large air gap. Once the energy is transferred to the secondary coil, it is converted back to direct current and stored in the vehicle's batteries.
The DOE is working towards a goal to develop a system that delivers 350 to 400 kilowatts and reduces the charging time for electric vehicles to 15 minutes or less.
According to Moe Khaleel, associate laboratory director for Energy and Environmental Sciences at ORNL, the latest breakthrough is a major step towards greater adoption of electric vehicles by increasing their range and speeding up the recharging, which in turn supports an energy-efficient mobility system for the nation's economic success.
Dynamic wireless charging at highway speeds is the next goal for ORNL researchers.