The Porsche Taycan recharges with direct current up to 270 kW. And now it does it without cables. That's right, because researchers at the US Department of Energy's Oak Ridge National Laboratory have succeeded in transferring energy into the German electric sports car's battery pack at a power output of 270 kW using wireless charging.

The initiative, whose partners include Volkswagen Group of America, developed a polyphase induction technology designed in-house by the team of US scientists.

From 100 to 270 kW

The result was announced with great enthusiasm. In March, in fact, the Oak Ridge scientists had managed to recharge a car at 100 kW. So, all things considered, they have improved performance by more than two and a half times in just a few months.

Lee Slezak, technology manager for grid and charging infrastructure at the DOE Vehicle Technologies Office, commented: 'In the past three months, ORNL's research groups on vehicle power electronics and electric drives have set impressive world records for induction charging. These achievements will further accelerate the adoption of electric vehicles in the US.

A system for everyone

Among the advantages offered by the technology developed at Oak Ridge National Laboratory is that of weight and bulk. A wireless charging system must be fast, reliable and space-saving. To keep the masses down and make these devices suitable for use in compact passenger cars or, as in the case of the Taycan, sports cars, companies generally work on systems with power ratings between 11 and 20 kW. Here we are on completely different orders of magnitude, but still without major changes on the kilo and centimetre front.

This is because it uses polyphase electromagnetic coupling coils with a 19-inch diameter, which are characterised by a higher power density and, thanks to a special design, the work of US engineers, also allow extremely high power levels to be transferred using rotating magnetic fields.

Volkswagen engineers evaluate wireless charging together with ORNL scientists

The entire system is seamlessly integrated into the car chassis and also features protection systems that prevent current voltage limits from being exceeded, as well as averting the danger of overheating and short circuits.

Going into production

'The receiver coil designed for the Porsche Taycan research vehicle can achieve 8 to 10 times the power density of existing systems,' said ORNL's Omer Onar, leader of the Vehicle Power Electronics group and lead researcher of the Porsche demonstration. Per kilowatt of weight, this is also the lightest charging system in the world'.

The American laboratory and Volkswagen's US subsidiary said they will continue their collaboration to further develop the system and create a variant suitable for home use.

"We are also working with Volkswagen on the development of a polyphase system for residential charging applications and collaborating on the development of a lightweight casing design that will improve mechanical, electrical, thermal and magnetic performance," Onar said. "Our goal is to mature the technology so that it is ready for implementation in production vehicles."