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Wireless charging technology for electric cars unveiled

Wireless charging for electric cars took a step forward last week when a new firm unveiled its technology in London.

HaloIPT, a spin-out from Auckland University in New Zealand backed by UK engineering consultancy Arup, is running a series of pilot projects and hopes to develop a commercial-scale demonstrator by 2012.

The company believes the technology, which transfers energy by magnetic induction, could one day be deployed on roads to allow electric vehicles to charge as they drive.

Chief executive Anthony Thomson said this would not only eliminate the inconvenience of plugging in the cars but would also remove so-called range-anxiety about running out of power.

‘When you have ubiquity you can start to forget about charging the car,’ he said.

HaloIPT’s charger works in the same way as electrical transformers, creating a magnetic field from a pad on the ground that induces an electric current in a receiver pad attached to the bottom of the car.

‘We’re taking the transformer out of the charger, pulling it apart and putting one side in the road and the other in the car,’ added Thomson.

The company’s co-founder, UniServices (Auckland University’s R&D firm), first developed a wireless electric vehicle charger in 1996 and for the last 10 years has used it with two fleets of electric buses in Italy.

Similar technology is already used for charging mobile phones and electric toothbrushes. Nissan last year revealed it was developing its own wireless chargers but has yet to add them to its cars.

HaloIPT’s charger can operate with a gap between pads of up to 400mm, enough to allow it to work with sport utility vehicles. An on-board control system means the power transferred is the same whatever the size of the gap and the firm claims the system is very tolerant to parking misalignment.

In order to allow the technology to compete with existing cable charging, the firm is aiming for equivalent costs and a 90 per cent transfer efficiency. But the first models would likely operate alongside a cable charger, which would add to the initial cost.

The tightly shaped magnetic field generated is around one-tenth of the strength of the Earth’s own field and is only activated when the car is on top of the pad. However, Thomson recognised that public perception of safety issues could be a barrier to widespread acceptance of the technology.

Part of HaloIPT’s vision for the future is to have charging pads installed in roads to create special charging lanes with enough power transfer to allow electric cars to maintain or even increase their battery power as they drove.

Thomson said this could be made practical by having power cables buried deep within the road in order to avoid them being disturbed by maintenance works. Two wireless transfers would then take place: one between the cable and the road pad, and another between the road pad and the car.

Power transfer could also be made reversible and the car battery used to easily store electricity at off-peak times, ready to be sold back to the grid when demand is high.

‘This is part of the socialisation of energy, where more people are generating and returning electricity to the grid as well as using it,’ said Thomson.

Readers' comments (15)

  • No relation to Hornby Scalextric or Ideal TCR (Total control racing) I suppose

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  • This has already been tried and was a total disaster as it had so many incurable problems, on such a large scale it would be much worse.

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  • I would be heavily concerned about Health and Safety issues? I assume it is not straightforward to transmit high power ( I guess a few 100 Watts) EM fields into open space without exceeding H&S limits (ICNIRP)

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  • "The tightly shaped magnetic field generated is around one-tenth of the strength of the Earth’s own field"

    This does not seem practical, considering even a tightly coupled transformer has stray magnetic fields far exceeding Earth's own field. How can you achieve this performance with a 400mm gap?

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  • Only a comparatively few people own a home with off street parking. It is this fundamental fact that makes electric cars impractical for most of the population. Whether cabling charging or wireless charging, cars must be able to park right by the owners house; even then, considerable specialised electrical work will be required before easy charging can be undertaken. Electric cars will most likely be bought by a few well off geeks who will tend to have solar panels and micro-CHP as well.

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  • Just show us the sums and we'll make up our own minds.

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  • Interesting idea, and despite the cold water applications by some commentators, Bombardier have applied the concept of power transfer to trams, with a primary winding (or rather windings) in the roadway and a secondary on board. OK, it's immdiate use power rather than charging, but the principle would appear to work. None too sure about the transfer efficiency, although the clearance between the two coils will be under closer control with steel wheels on steel rails.

    Against.. well, as the owner of a Pacemaker for 14 days now, I hope 'charging rectangles' will be well-marked - at least until they come up with Mk II Pacemakers which can be topped up at someone else's expense!

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  • Ten million homes in the UK consuming an average 10KWatts is 100 GigaWatts. 30 million cars with an average power demand of 50KWatts (67 Brake Horse Power is not a lot) is 1.5 TeraWatts or fifteen times the UK's household power demand. I haven't even touched on the thorny transfer efficiency of all this power, so where do they imagine all this power for electric vehicles will come from ?. And what effect do they think it will have on the environment ?. Someone really needs to think this through before publishing these silly ideas. Non starter ! !

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  • Induction seems to work just fine for buses in Italy since 2003 and recently in the Netherlands:

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  • Direct contact charging via metal plates in the curb that are hot only when covered by an approved vehicle is simpler and cheaper. See Curb Connect,

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