Capacity leap for electric vehicle wireless charging

May 11, 2016

Rapid charging of electric vehicles using wireless power transfer is on the horizon following the test of a new high power demonstrator system in the US.

Similar to the low-power devices charging household items like toothbrushes or razors, wireless power transfer (WPT) offers a number of advantages to electric vehicle owners. With no plugs, WPT offers convenience and compatibility.

Now a 20 kW wireless charging system has been demonstrated at the US Department of Energy’s Oak Ridge National Laboratory, with 90% transfer efficiency.

The Oak Ridge National Laboratory’s 20kW wireless power transfer system could mean more convenient and faster charging of electric cars
The Oak Ridge National Laboratory’s 20kW wireless power transfer system could mean more convenient and faster charging of electric cars

Standard ‘Level 2’ plug in chargers operate at around 7 kW, allowing the wireless system to charge a typical EV battery in around a third of the time of typical wired systems.

Working with industrial partners from Toyota, Cisco Systems and Evatran on the 20 kW system, the researchers say they are already looking ahead to their next target of 50 kW – matching power levels found in plug-in quick chargers.

“We have made tremendous progress from the lab proof-of-concept experiments a few years ago,” said Madhu Chinthavali, ORNL Power Electronics Team lead. He added: “We now have a technology that is moving closer to being ready for the market.”

ORNL’s power electronics team achieved the 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.

Editor’s comment: The convenience of wireless charging coupled with rapid charge cycle times could increase consumer acceptance of electric vehicles. Furthermore, inductive wireless power transfer offers the possibility of dynamic charging – powering vehicles while on the move. Such a development could effectively remove the need for ‘refuelling’ altogether.

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