Wirelessly charging an electric vehicle is still very much a distant dream. While there are startups out there that offer commercial solutions, their speeds and integration into existing vehicles aren’t particularly user-friendly, with peak rates rarely going over 11 kilowatts.
That said, things could soon change dramatically because a modified Porsche Taycan that was lent by Volkswagen Group of America to the Department of Energy’s Oak Ridge National Laboratory (ORNL) set a new record for the fastest wireless charging session on a light-duty passenger vehicle.
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The state of EV wireless charging
Wireless charging is not what we were promised. Not for smartphones and definitely not for electric cars that have to carry huge batteries to get decent range. With charging speeds of just 11 kilowatts on most readily-available systems, you're better off just plugging in a cable. But research shows there's huge potential for the technology.
Using a novel polyphase wireless charging system that was seamlessly integrated into the EV’s underbody, researchers managed to transfer a peak power of 270 kW to the German sports sedan–the same as the car’s maximum DC charging rate. And before you get your fingers fired up, know that this is the previous-gen Taycan we’re talking about here, not the new and improved version that can take up to 320 kW from a compatible stall.
The power transfer system invented by the ORNL uses lightweight electromagnetic coupling coils with a diameter of just over 19 inches that allow for higher power density in the smallest possible coil. The government-run lab said that the process is similar to the systems found in small consumer devices like smartphones, but the main difference is the polyphase coils in the development Taycan feature rotating magnetic fields generated by the coil phase windings to boost the power to unprecedented levels.
“The receiver coil designed for the Porsche Taycan research vehicle can achieve 8 to 10 times higher power density compared to existing systems,” said ORNL’s Omer Onar, leader of the Vehicle Power Electronics group and lead researcher on the Porsche demonstration. “Per kilowatt weight, this is also the most lightweight charging system in the world.”
The distance between the sender unit on the ground and the receiver on the car was 4.85 inches, with the system achieving an impressive efficiency of 95%. This means that the lab’s wireless charger can increase the car’s state of charge by 50% in just 10 minutes–just like if a DC cable was plugged into the charge port.
This isn’t the first time the ORNL broke records with their wireless charging tech. In 2016, the team achieved a wireless transfer rate of 20 kW on a Toyota RAV4 equipped with an additional 10-kilowatt-hour battery. Last year, a charging speed of 120 kW was recorded with a Hyundai Kona.
So, when will we, the public, be able to fast-charge without having to deal with cables? We’re not sure. The 270 kW demonstration was the closing act of a DOE-funded project that the ORNL and Volkswagen announced in 2021. However, all hope is not lost, as the research lab and the automaker plan to continue working together in the near term to improve the system and make it smaller, more cost-effective and easier to manufacture on a large scale.
