ORNL surges forward with 20-kilowatt wireless charging for vehicles

ORNL surges forward with 20-kilowatt wireless charging for vehicles
Oak Ridge National Laboratory's 20-kilowatt wireless charging system features 90 percent efficiency. Credit: ORNL

A 20-kilowatt wireless charging system demonstrated at Department of Energy's Oak Ridge National Laboratory has achieved 90 percent efficiency and at three times the rate of the plug-in systems commonly used for electric vehicles today.

This ability can help accelerate the adoption and convenience of . Industry partners from Toyota, Cisco Systems, Evatran, and Clemson University International Center for Automotive Research contributed to the technology development demonstrated today at ORNL.

"We have made tremendous progress from the lab proof-of-concept experiments a few years ago," said Madhu Chinthavali, ORNL Power Electronics Team lead. "We have set a path forward that started with solid engineering, design, scale-up and integration into several Toyota vehicles. We now have a technology that is moving closer to being ready for the market."

ORNL's electronics team achieved this world's first 20-kilowatt wireless charging system for passenger cars by developing a unique architecture that included an ORNL-built inverter, isolation transformer, vehicle-side electronics and coupling technologies in less than three years. For the demonstration, researchers integrated the single-converter system into an electric Toyota RAV4 equipped with an additional 10-kilowatt hour battery.

The researchers are already looking ahead to their next target of 50-kilowatt wireless charging, which would match the power levels of commercially available plug-in quick chargers. Providing the same speed with the convenience of wireless charging could increase consumer acceptance of electric vehicles and is considered a key enabler for hands-free, autonomous vehicles. Higher power levels are also essential for powering larger vehicles such as trucks and buses.

As the researchers advance their system to higher power levels, one of their chief considerations is safety.

"The high-frequency magnetic fields employed in power transfer across a large air gap are focused and shielded," Chinthavali said. "This means that magnetic fringe fields decrease rapidly to levels well below limits set by international standards, including inside the vehicle, to ensure personal safety."

Convenience and simplicity are at the heart of the ORNL system, which places a strong emphasis on radio communications in the power regulation feedback channel augmented by software control algorithms. The result is minimization of vehicle on-board complexity as ORNL and partners pursue the long-range goal of connected vehicles, wireless communications and in-motion charging. While the team's initial focus has been static, or motionless, , the researchers also evaluated and demonstrated the system's dynamic charging capabilities.

Energy Efficiency and Renewable Energy's Vehicle Technologies Office provided funding for this competitively-selected project as part of a broad portfolio in support of DOE's EV Everywhere Grand Challenge, which aims to make as affordable to own and operate as today's gasoline-powered vehicles by 2022.

"Wireless power transfer is a paradigm shift in electric vehicle charging that offers the consumer an autonomous, safe, efficient and convenient option to plug-in charging," said David Smith, systems program manager. "The technology demonstrated today is a stepping stone toward electrified roadways where vehicles could charge on the go."


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Mar 31, 2016
Those Power Transmitting Plates must be placed every 50 yards on highways/roads and you should never worry hereafter about keeping the battery of the car charged. No stopping of the cars to get them charged anymore!
Also, just drop the cellphone into a small tunnel by the side of the seat and once the phone is charged, it should come back up AUTOMATICALLY!

Mar 31, 2016
"Those Power Transmitting Plates must be placed every 50 yards on highways/roads and you should never worry hereafter about keeping the battery of the car charged. "


The 90% efficiency applies for a single plate when the car is actually on it. The standby-power waste for a whole system of chargers along a road would be atrocious because each would be powering a car for only a split-second as it passes over.

A plug-in system is still more efficient and can handle more power. The problem is rather that households don't have high enough amperage to feed the car - or this charger - on the normal utility connection because fitting whole neighborhoods with high power chargers would turn out with supply problems and local system overload.

An EV represents similiar total electric energy demand as an average house, so a neighborhood with EVs is like a neighborhood with twice as many homes even on slow charge.

Mar 31, 2016
"The high-frequency magnetic fields employed in power transfer across a large air gap are focused and shielded," Chinthavali said. "This means that magnetic fringe fields decrease rapidly to levels well below limits set by international standards, including inside the vehicle, to ensure personal safety."


Uh huh... And that 50kW oscillating magnetic field isn't going to cause interference? Get ready for the Interference Era guys, the time when nothing will work because there will be massive RF energy blasting in every direction...

I mean damn, why not just give every American a 50kW broadcasting tower and let'er rip. What could possibly go wrong?

Why can't we just stick with wires? They are 100% efficient and if using DC, interference-free.

Mar 31, 2016
Noted in the article, 20 and 50 kW are more appropriate for larger vehicles (perhaps commercial), and vehicles that might have to recharge several times a day in public, such as busses.

Higher power levels are also essential for powering larger vehicles such as trucks and buses.


As Eikka says, such a charger is unsupportable as a high-density, suburban feature.


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