Wireless EV charging while you drive a thing of the future

Research is being done to look at the feasibility of wireless charging on parts of State Highway 1, writes Nile Bijoux.

Researchers from the University of Auckland are evaluating the impact of adding wireless electric vehicle charging pads to a section of State Highway 1, including economic feasibility, charging lane length, effects on traffic flow and energy consumption.

Wireless charging in a road surface, also called ‘‘dynamic wireless charging’’ (DWC), uses electromagnetic induction to juice electric vehicles while they’re moving.

The researchers digitally simulated traffic flow and a ‘‘state of charge’’ model to evaluate the impacts of wireless charging facilities using a 90km section of State Highway 1, from near Billing Rd to the Pokeno interchange.

‘‘We found that the total investment cost of a DWC facility in the corridor for a system with a 50-kilowatt inductive power transfer capacity is $1.59 million a year when traffic flows freely compared to $1.42m a year in the case of peak hour traffic.’’

Lead student researcher, Ramesh Majhi clarified the cost figures involve upgrading lanes to use DWC infrastructure, not the operational or maintenance cost.

The variation in the figures is because of faster-moving traffic out of peak hours, meaning more charge-capable road is required to satisfy energy demand.

Without considering the time it would take to drive to a static charging station, wireless charging only becomes less costly at 125kW and above. Taking travel time into account means wireless in-road charging becomes less costly at 75kW and above.

However, the paper says that when comparing static and dynamic charging, it is ‘‘imperative to consider the value of time (travel time, delay, and charging time), which is substantially more for plug-in charging stations compared to inroad wireless charging’’.

Plus, the population of electric vehicles is only growing. Existing plug-in stations can only serve limited numbers of EVs at any given time, so if owners can charge their vehicle as they drive, the bottleneck at static chargers will lessen. As for safety, the tech generally works via a handshake system between the induction coils in the tarmac and the receiver in the car. Basically, the induction coils lie dormant until the car drives over top and activates them.

Majhi said electromagnetic radiation is ‘‘not a concern at all for the occupants’’.

‘‘All the necessary electronics and electrical components in the wireless charging pads on the pavement conform to international safety standards. The test results show that there is no harm to the drivers or any other occupants as there is no electromagnetic radiation. As there is no direct interaction between the occupant and the pads, there are no safety hazards involved.’’

The work was published in the international journal Sustainable Cities and Societies, and used various scenarios and measures, including four different inductive power transfer capacities (50, 75, 100, and 125 kilowatts), real traffic data and two types of traffic conditions – peak hour and free flow, to evaluate the performance of DWC systems.

As for when we might actually see DWC in our highways, there’s a long way to go yet. Majhi said that prototypes are being tested and developed around the world, including at the University of Auckland.

‘‘DWC will take at least five to 10 years to be seen on New Zealand roads as several factors, such as prototype development, testing, financial feasibility, and policy measures need to take place sequentially for a successful uptake.’’