Electric avenue – the future of car charging is electric roads

Electric avenue – the future of car charging is electric roads
Electric avenue – the future of car charging is electric roads

By the mid to late 2020s it’s entirely possible that you’ll be able to charge an electric vehicle simply by driving it over special ‘electric roads’.

Senior Renault EV engineer Virginie Maillard has said that “maybe ten years is a good timescale for this technology… we have to design cars and the road network to accept it.”

These ‘electric roads’ with multiple pads under the surface may actually be ready before the cars, which will need to have special induction charging pads built into them.

Induction charging technology is now being looked into at a purpose-built test track near Paris. Renault Kangoo ZE vans are being equipped with Halo wireless induction charging equipment supplied by US tech company Qualcomm, more widely known for their mobile phone chips. Qualcomm will develop the technology and earn royalty payments from the car manufacturers who adopt it.

1 In-car control box smooths the signal of induced 80Hz current.
2 Induction coil under the road is similar to the car-borne plate. Inside are two coils in a ‘double-D’ configuration of Litz wire.
3. Under the car are two induction plates with copper wire ‘Litz’ coils. Litz wire is insulated to ensure a good-quality induced current.
4. Roadside electronics box. Delicate circuitry is housed above ground in a weatherproof enclosure.
5 Each under-road charging coil is rated at 22kWh. Pulses flow into the battery and then the motor.

The system is a bit like that used to charge electric toothbrushes. Coils in the car and the road ‘connect’ wirelessly to keep the EV’s battery charged up. Even though the coils are only in range for a fraction of a second at the maximum charging speed of 60mph, as much as 20kW of energy can be pulsed into the EV as it goes along – which is approximately the amount it uses when cruising. The wireless system has been programmed by Qualcomm to reduce the energy pulses to 5kW in stop-start traffic.

Research suggests that only a quarter of a 1km stretch of motorway needs to be fitted with the pads in order for an EV to drive along it in an ‘energy-neutral’ way.

It’s possible that the third-generation Renault Zoe, due in the mid-2020s, could have this induction charging technology.

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