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ORNL demonstrates 120 kW wireless charging for vehicles; 97% efficiency

Researchers at the Department of Energy’s 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 gasoline station fill-up.

The wireless system transfers 120 kilowatts of power with 97% efficiency, which is comparable to conventional, wired high-power fast chargers. In the laboratory demonstration, power was transferred across a six-inch air gap between two magnetic coils and charged a battery pack.

03 Wireless Coil

ORNL researchers used computer simulations to design coils that generate the magnetic field required for wireless power transfer.

ORNL researchers created and demonstrated the world’s first 20-kilowatt wireless charging system, which is being modified for applications such as commercial delivery trucks. (Earlier post.)

It was important to maintain the same or smaller footprint as the previous demonstration to encourage commercial adoption.

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.

—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.

The system’s architecture takes energy from the grid and converts it 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 a vehicle’s batteries.

The demonstration advances DOE’s extreme fast-charging goal to develop a system that delivers 350 to 400 kilowatts and reduces the charging time for electric vehicles to 15 minutes or less.

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.

The research was funded by DOE’s Vehicle Technologies Office (VTO) and performed at the National Transportation Research Center, a DOE user facility at ORNL.



"..rival the speed and convenience of a gasoline station fill-up."
Not really.


@SJC Yea, a fully drained Tesla would still need 37.5 minutes to charge at 120KW which is what Tesla superchargers output. When bumped up to 400KW charging rate it would require 11.2 minutes which the battery isn't even capable of handling without sacrificing degradation. Considering a Model 3 battery is 375 volts 400KW charge rate requires 1,066 amps necessitating a giant radiator or a cooling fan that sounds like a jet engine.


I think it is a good development, but exaggeration is not necessary.


This is doing it the hard way.  Siemens E-highway is already in pilot-scale operation.  System voltage is 700 V, typical impedances are milli-Ω so feasible power levels are in the megawatts.

The overhead lines avoid the following costs of wireless:

  1. Expensive conversion electronics.
  2. Cost of ripping up pavement to install or repair coils.


@Engineer-Poet The greatest part of the Siemens E-highway is patents are expired so mass adoption of this would be significantly cheaper as competition exists without the need to license the usage of said tech. Another interesting aspect I would love to see data for are the safety increase, power production, and increased lifespan of brakes on E-highway going downhill in mountainous terrain.


I never thought about regenerative braking for mountain descents, though even a hybrid truck would be able to use it to some extent.


It is irrelevant to the charger that the battery can't handle high current inputs as that is under the batteries management control. .

I don't think you are up to date with the 5 and 10 minute to 80% charge figures that have been around for most of this year.

Tomorrows technology will be more able and besides toda'ys trucks and supercars can deliver those amounts of power.

The main point to this is the possibility to deliver higher efficiency and power capabilities. Effectively simply refining the standard practice in higher f magnetic permeability .

As it is reasonable to assume that you will be able to order a brew and let the system do it's job while you stretch your legs the rfid takes care of the billing, it shouldn't be hard to see it as time saving.

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