A new wireless EV charging pad can fill a car's battery as efficiently as a wired plug, at groundbreaking 100 kW power levels – unlocking the possibility of fast, efficient and super-convenient charging simply by parking in a designated spot.
Wireless power transfer was famously first demonstrated in the 1890s by one Nikola Tesla. Today, it's fairly commonplace in many homes, where plenty of folk use wireless charging pads for phones, tablets and electric toothbrushes, as well as inductive cooktops. The power is transferred from the charger to the device through the interaction of electromagnetic fields, and what was once dark magic is now considered a safe, convenient and efficient way to get the job done.
It hasn't really taken off in the EV world, though – largely because the power levels have kept things squarely out of the fast-charging realm. For example, according to Verified Market Reports, one of the fastest commercially-available wireless EV pads is Hevo's 12 kW jobbie. That's better than a wall plug; it's a level 2 charging speed and would give you somewhere around 42 miles (68 km) of driving per hour from a medium-efficiency (3.5 miles/kWh, or 5.6 km/kWh) electric car. But it's certainly not what you'd hope for from a commercial charge station.
That's why a new solution announced by Oak Ridge National Laboratory (ORNL) is looking very promising.
ORNL researchers say they've demonstrated the fastest, most powerful wireless EV charger ever, in a "lightweight polyphase electromagnetic coupling coil design" that transfers power more than eight times faster than the Hevo pad, enough to get the same car around 350 miles (563 km) of charge in an hour.
A receiver coil was fitted to a Hyundai Kona EV, which parked over a 14-inch diameter polyphase transmitter, with a five-inch air gap in between. The system was measured at 100 kW, with 96% efficiency – comparable to what you'd get from a very good cable and plug. The researchers note that conventional coil technology in a benchtop lab test has transferred power at 120 kW, but say this is the best that's ever been tested on a car – and that the polyphase coil design allows for the highest power density within the smallest coils possible, making for a relatively compact and covenient system.
“We’ve achieved the highest power density in the world for a wireless charging system for this class of vehicle,” said ORNL’s Omer Onar in a press release. “Our technology reaches power densities 8-10 times higher than conventional coil technology and can increase battery charge state by 50% in under 20 minutes… This is a breakthrough achievement, and opens the door to fast and efficient wireless charging for passenger electric vehicles.”
Of course, for any wireless charging solution – including ones embedded into the road surface – to really gather much momentum, a lot of things need to happen, starting with car manufacturers settling on standards and building the receiver coils and charging gear into their vehicles. It's a bit of a chicken-and-egg situation; few manufacturers are fitting the coils, since few companies are building the infrastructure at scale, and vice versa.
But it does seem like something both sides want to achieve. Perhaps Tesla is the company to make it happen, since it operates on both sides of the fence, developing the vehicles as well as its own fast charging network. And indeed, it's in the works, according to Energy Matters.
We shall see! But the technology certainly seems capable of making wireless EV charging relatively quick and efficient, even if it's not yet ready to challenge the fastest wired connections in the EV charging world.
Source: ORNL
