Wireless charging technology for electric cars unveiled

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.