Wireless charging autonomous cars.

Google’s prototype self driving car; image courtesy of Google

Google’s parent company, Alphabet, is testing technology that would make it possible for self-driving cars to be charged wirelessly, Mark Harris wrote for IEEE Spectrum. 

Documents filed at the U.S. Federal Communications Commission (FCC) suggest that Google is working toward cutting its robocars’ charger cables and beaming power to them instead.

Chris Urmson, director of Google’s self-driving car program, said self-driving cars will be a boon to many people, “ranging from [those with] vision problems to multiple sclerosis to autism to epilepsy who are frustrated with their dependence on others for even simple errands.” However, few of those people (along with children and people using autonomous cab services), can be expected to recharge the self-driving cars, said Omer Onar, an Oak Ridge National laboratory researcher who is a member of the committee writing the wireless vehicle charging standard.

Two Wireless Charging Systems

Alphabet is testing at least two wireless charging systems to power its electric autonomous cars,  Kirsten Korosec wrote for Fortune. A year ago, the FCC granted permission to a company in New York, Hevo Power, to install an experimental charger at Google’s headquarters in Mountain View, California. And in July of last year, the FCC gave the go-ahead to Momentum Dynamics to install its equipment at the secret X division location where Google’s self-driving cars are being developed.

Harris related some technical details:

Both companies’ systems transfer power from a transmitter embedded in the ground to a receiver on the underside of an electric vehicle, using a principle called resonant magnetic induction. In this process, an alternating current passing through a tuned electrical circuit creates an oscillating magnetic field. That field then induces another alternating current in a second, nearby circuit tuned to the same resonant frequency.

The technology Hevo is testing at Google headquarters involves a prototype charger called Alpha that is able to give a vehicle 1.5 kilowatts of power from a circular transmitter embedded in pavement, which looks like a manhole cover. Although the FCC did not reveal the specifications of the Momentum Dynamics system, MD said its wireless transmitters have power ratings of up to 200 kW.

Reducing Need for Batteries

In the proposed systems, self-driving cars would be positioned over a charging pad between rides, Harris wrote. Eventually once changes are made to road infrastructure, it may be possible for autonomous electric vehicles to recharge themselves as they drive. Such a system would pave the way for self-driving cars to have much smaller, lighter batteries than those currently required for electric vehicles, which need to carry all of their energy. Reducing the battery size would help reduce the price of electric cars since batteries are their most expensive parts. MD CEO Andy Daga told Harris that his company’s high-power chargers are already recharging electric bus batteries in just minutes so the buses can be in service 24 hours a day.

Here is a video about Momentum Dynamics’s charging systems:

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