Wireless Inductive Charging

UK Highways Agency Confirms Electric Car Wireless Charging Motorway

It’s official: the UK Government has plans to electrify sections of the UK motorway network to test electric car wireless charging technology.

That’s according to the IET’s Engineering and Technology Magazinewhich says the Highways Agency has confirmed its plans to electrify at least part of an English motorway to better understand and test the feasibility of wireless power transfer.

Swedish automaker Volvo has already conducted some wireless road-based charging trials

Swedish automaker Volvo has already tested some wireless charging systems, but it’s not sure who will take part in the Highways Agency trials.

Confirming an off-the cuff remark made by a Highways Agency official at a recent ITS(UK) EV working group meeting, a spokesperson for the agency has said that the agency is planning a pilot wireless charging project involving passenger cars.

Currently, the only trials in the UK involving wireless charging have involved busses, with various projects — including one in Milton Keynes — focusing on static wireless charging. Essentially charging a bus while it waits at a stop, static inductive systems require a vehicle to be parked over the top of a specially-designed charging plate installed into the tarmac.

In this setup, a current flows through the plate, inducing a locally-targeted electromagnetic field which can then be picked up by a receiving plate on the underside of the vehicle, inducing a current flow in the receiving plate of the vehicle and thus transferring power.

RELATED: How Milton Keynes is Kickstarting Electric Bus Revolution

The proposed trial, the details of which are still scarce at the time of writing, involves placing inductive plates at regular intervals along a roadway, transferring power to electric vehicles as they pass over the plates.  This is known as a semi-dynamic charging system, since the vehicles are passing over static charging points on the road.

Cheaper to install and operate than a fully-dynamic system — where there’s a continuous inductive charging surface along the length of the road — the semi-dynamic system will be installed on a UK motorway at some point in the near future, the IET hints.

Because of the power used, the systems wouldn’t be used to charge electric car batteries from empty to full, however. Instead, they would operate in tandem with the vehicle’s on-board battery pack. In this way, the rate at which the car’s on-board battery pack is depleted would slow, resulting in far larger ranges without any increase in battery pack capacity or energy density.

While the Highways Agency hasn’t detailed the location of the trial, or how it will be implemented, it has issued a criteria for system adoption which includes a requirement that any inductive system is capable of lasting about the same length of time as the asphalt used to make UK roads. That equates to a lifespan of around 16 years of trouble-free operation, a massive target for an industry still in its infancy and where conductive charging stations — the ones you have to plug in to charge your car — still notoriously unreliable.

Wireless charging requires no wires between the charging station and the car.

Dynamic and semi-dynamic inductive charging relies on the car passing over charging pads embedded into the road.

By the time the Highways Agency decides on the location of the proposed trial, it’s likely a pilot project already destined to go ahead in Scotland this summer involving Transport Scotland, Scottish Enterprise and bus manufacturer Alexander Dennis will already be well underway. Due to start in Glasgow later this year, the bus-based trial will focus on semi-dynamic charging of hybrid electric busses in the Scottish city.

At the same time, the European Commission has allocated a massive €9 million to research programs involving dynamic charging of electric vehicles, indicating we think that not only governments are finally starting to become convinced of the benefits of electric cars, but that they are wanting to develop ways of enabling longer-distance EV trips that do not require users to stop every few hours for a half-hour recharging session.

Don’t think though that this means either static or dynamic inductive charging technologies are years from launch. Like other pilot projects and government-sponsored trials, it will be likely decades before wireless technology is cost-effective enough to be installed nationwide.


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  • Gert B. Bu00fcttgenbach

    This concept anticipates the driverless car – it has to stay in the track as accurately as possible at constant speed to get a maximum current induced.

  • At 300W/mile (3.3 miles/kWh) at 60 miles/hour (100 kph) would require ~18 kW for flat road in ideal weather conditions (no precip, nor headwinds) to maintain speed. If traffic becomes congested, more vehicles per mile, it means each vehicle will receive less power, but enough to maintain a slower speed. This seems doable, just a question of how much copper wire at current market price u2026 per mile?nnnote: current static wireless charging demonstrations typically rated under 10 kW per wireless connector.nnWhat will the electrified lanes be called? E-toll lanes?n

    • martinwinlow

      Hi Brian, You are assuming that the vehicle will obtain all its required power from the inductive ‘plates’ – coils in reality. It is much more probable that these inductive systems would only supplement the vehicles own power source, acting as a range extender. As Gert indirectly suggests, whilst one might imagine that even modest use of such technology would involve huge amounts of power on a busy motorway, if you throw in autonomous vehicles capable of forming long trains of very closely spaced vehicles – perhaps less than a metre between them – you then add a huge improvement in aerodynamic efficiency of the train as a whole. This might reduce the energy being used by the train to 1/10th or more of that of all the individual vehicles aloneu2026 All very interesting!nnnI’m not sure the author has quite grasped the detail correctly. I read about this proposed trial elsewhere and aside from what I understood as ‘dynamic inductive charging’ i.e. coils in roads providing energy to passing vehicles fitted with inductively matching coils, they were also proposing parking spots along the motorway (or whatever) where vehicles could stop and charge statically using the same technologyu2026 is it this that is actually ‘semi-dynamic’? If not, what is fully ‘dynamic’? MW

      • MrL0g1c

        if you throw in autonomous vehicles capable of forming long trains of very closely spaced vehicles

        Isn’t going to happen, not possible, no-one who says this has ever done the math, different braking distances even for cars with the same brake make and model means you won’t see car trains unless all of the cars promise not to ever emergency brake and to only brake slowly regardless of any emergency.

        LINK: Why it’s not possible

      • MrL0g1c

        This might reduce the energy being used by the train to 1/10th or more of that of all the individual vehicles alone

        Sounds massively over-optimistic to me, cars are already aero-dynamically designed, I doubt even 25% energy saving is possible.

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