Inductive charging gets green flag

  • 08-Aug-2011 04:46 EDT

Inductive power transfer (IPT) wireless charging uses strongly coupled magnetic resonance to transfer power from a transmitting pad on (or under, for dynamic charging) the ground to a receiving pad on the electric vehicle. (HaloIPT)

No pit stopping to refuel is an ideal scenario for motorsports teams, even if that “fuel” happens to be electricity. With “dynamic” (i.e., in-motion) charging technology, the prospect of electric racecars—as well as electric road-going vehicles—being charged on the go, without ever having to be plugged in, could become reality.

HaloIPT, a U.K.-based start-up that develops inductive power transfer (IPT) systems for wirelessly charging electric vehicles (EVs), recently formed a strategic partnership with Drayson Racing Technologies to test the technology on the track. They will also collaborate on the development of electric drivetrain packages to replace the racecar’s internal-combustion engine.

HaloIPT was founded in 2010 by the New Zealand-based R&D commercialization company UniServices, Trans Tasman Commercialization Fund, and design consultancy Arup.

“Dynamic wireless charging will be a real game-changer, enabling zero-emission electric vehicles to race over long periods without the need for heavy batteries,” said Lord Paul Drayson, former U.K. Minister for Science and Innovation and co-founder of the green R&D racing organization in 2007. “This is a milestone innovation that will have a dramatic effect not just on racing but on the mainstream auto industry. We’re looking forward to putting this technology through its paces as it charges electric racecars at speeds of up to 200 mph.”

The track an ideal test bed

The basic idea is that racecars, fitted with a receiver pad and controller, will continuously draw power from transmitters buried under the surface of the racetrack (or road in the case of passenger and commercial vehicles). The controller converts the magnetic energy to dc power to charge the battery.

“The power supply takes electrical power from the mains supply and energizes a lumped coil, with a current typically in the range 5-125 A,” Dr. Anthony Thomson, Chief Executive at HaloIPT, explained in more detail. “Power is transferred by tuning the pick-up coil to the operating frequency of the primary coil with a series or parallel capacitor. The power transfer is controllable with a switch-mode controller. In an electric vehicle, IPT wireless charging uses strongly coupled magnetic resonance to transfer power from a transmitting pad on the ground to a receiving pad on the car.”

An obstacle for mainstream dynamic inductive charging is the costly and time-consuming effort of installing the charging circuits beneath millions of miles of established roadways. So the comparatively short, confined surfaces at racetracks present an ideal test bed for the technology.

Initially, the companies plan to establish trackside charging systems, a setup similar to how racecars currently refuel by pulling off. HaloIPT static charging systems are expected to be installed in the pit lane by Q3 2012.

Development of the dynamic charging system with Drayson will continue throughout 2013 and 2014, Thomson said. If all goes according to plan, by Q3 2015 the dynamic charging system will be installed in the main track and demonstrated in races.

To maintain a continuous charge, “we would place the pads at 1 per lineal meter with a gap of 250 mm between each pad. So there would be 100 pads/100 m,” he shared.

Which racetrack will be outfitted with this infrastructure has not yet been revealed.

A ‘vehicle agnostic’ technology

Inductive charging itself is a proven technology. Some common home applications include toothbrush chargers, induction cooktops, and more recently chargers for electronic devices such as cell phones. Even theme park rides have exploited the technology.

“Wireless charging has been used worldwide for close to two decades, in materials handling, auto assembly, factory automation, and clean room robotics,” Thomson explained. “However, the systems developed for materials handling all rely on computer- or track-controlled guidance systems to ensure the vehicles follow a tightly defined route. HaloIPT’s new dynamic charging technology…is tolerant to large misalignment [with the transmitter pads] to allow cars, trucks, and buses to travel freely and still pick up high efficient charge.”

The IPT system automatically adjusts for changing vertical gap; the gap between a vehicle and a pad can be up to 400 mm (15.7 in). The lateral alignment between vehicle and pad can be ±250 mm (9.8 in) with “minimal loss of efficiency,” according to HaloIPT.

The pads themselves measure 600 x 400 x 30 mm (23.6 x 15.7 x 1.2 in) for a 3.3-kW “small-car” system. The company claims very low magnetic field emission from the system, conforming to ICNIRP (International Commission on Non-Ionizing Radiation Protection) guidelines, and no electromagnetic interference into the vehicle.

Multiple IPT systems have been (or are being) developed to suit different applications. The one for small cars was demonstrated in London late last year in a Citroën C1 converted by Electric Car Corp.; a 7-kW system for larger cars is featured on the Rolls-Royce 102EX, an experimental electric Phantom launched at the Geneva Motor Show in March; and a new 18-kW product suitable for EV fleets (i.e., taxis, delivery vans, and trucks) is under development and expected to deploy in 2012. Trials with fleet owners in the U.K. and European Union, as well as in North America, are in the planning stages.

Commercial systems from HaloIPT’s co-founder UniServices, with power levels up to 60 kW, have been successfully operating in two fleets of buses (approximately 40 buses in total) for 10 years in Turin and Genoa, Italy.

“IPT is a vehicle agnostic technology and can therefore be used to power any type of electric vehicle regardless of size and weight,” Thomson said. “HaloIPT’s system allows cars, vans, buses, and trucks to travel along the same stretch of IPT highway, with each vehicle harvesting the appropriate amount of energy, controlled from within the vehicle.”

The time it takes to recharge an EV with the static system depends on the model and battery size. “However, HaloIPT’s systems are comparable to a plug-in system, so it will take the same length of time,” he claimed. “If you take a 20-kW·h system that would have a usable 15 kW·h, this would take five hours to charge with a 3-kW IPT system.”

Infrastructure deployment

To expedite the process of bringing inductive charging—and by extension, plug-less EVs—to the mainstream, HaloIPT has been working with a number of public sector bodies including Transport for London (the local government body responsible for most aspects of the transport system in Greater London), TSB CABLED (the U.K.’s largest trial of EVs), and Oxford Brookes University. It has partnered with several private companies as well.

One recent agreement, between HaloIPT and Evida Power Ltd., a manufacturer of lithium-ion battery packs for EVs, will jointly explore the feasibility of the manufacture of 40,000 IPT systems over a five-year period. The goal is to develop a long-term venture for deployment of the system, which is intended as a specification option on a forthcoming EV (the make and model could not yet be revealed), with sales estimated to reach 70,000 units by 2015.

The start-up also recently formed a strategic partnership with Chargemaster PLC to manage the low-volume build, manufacturing, and infrastructure planning for its IPT systems in the U.K. and Europe. By Q2 2012, the two companies expect to have plans in place for Chargemaster to oversee the delivery of fully assembled and tested production IPT systems, including primary and secondary pads, power supplies, and associated controllers, ready for deployment.

“We are now working tirelessly with numerous government bodies and private companies to define infrastructure deployment projects, which represent the key next stage of development for charging network implementation,” Thomson said. “There is a need for governments and private-public partnerships to deploy the infrastructure to encourage the production of EVs with smaller battery packs.”

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