Researchers highlight the benefits of dynamic wireless systems for charging electric vehicles on-road.
University of Auckland researchers are accelerating the drive towards more sustainable travel by investigating the feasibility of wireless in-lane charging for electric vehicles.
The impact of wireless electric vehicle (EV) charging pads on a section of Auckland motorway, including economic feasibility, charging lane length, effects on traffic flow and energy consumption, is examined in their study.
Engineering PhD candidate Ramesh Majhi, senior lecturer Dr Prakash Ranjitkar and Dr Selena Sheng have developed a traffic simulation framework and a “state of charge” model to evaluate the impacts of dynamic wireless charging (DWC) facilities using a 90km section of State Highway 1.
It focused on DWC pads being embedded into the road and using electromagnetic induction to charge EVs while they are being driven.
The researchers investigated the economic feasibility of the wireless system in terms of the total cost associated with a part of SH1 by comparing it to the cost associated with using plug-in charging stations within 1km of the highway corridor.
The total investment cost of a DWC facility in the corridor for a system with a 50kW inductive power transfer capacity came in at $1.59 million per year when traffic flows freely compared to $1.42m annually in the case of peak hour traffic.
The cost variation, says Majhi, is due to faster speeds when traffic moves freely, hence more charging length is required to satisfy the demand.
Without considering the time it would take to drive to a static plug-in station, a wireless charging lane would only be less costly at 125kW and above, according to the paper.
However, when comparing the feasibility of both charging facilities in terms of total cost, the researchers say it’s imperative to consider the value of time – travel time, delay and charging time. This is substantially more for plug-in charging stations compared to in-road wireless charging.
And at a higher inductive power-transfer capacity, such as 75kW and above, the wireless in-road charging facility becomes less costly compared to the typical plug-in set-up under peak-hour conditions when taking the cost of travel time into account.
Meanwhile, as the EV population increases, the time costs tend to become more significant to utilise plug-in charging stations, which will make DWC more feasible and competitive in the future, say the researchers.
“As existing plug-in stations can handle limited EVs at a given time and with the increase in charging demand, the wireless in-road facility will soon become more competitive compared to the current plug-in stations due to savings in costs associated with travel time, delay and charging time.
“Moreover, with advanced research in dynamic wireless charging system components, the construction cost of a wireless charging lane will eventually decrease making it more feasible than existing plug-in charging.”
Their work, published in the international journal Sustainable Cities and Societies, is titled “Assessment of dynamic wireless charging based electric road system: A case study of Auckland motorway”. It uses various scenarios and measures, including four different inductive power-transfer capacities of 50, 75, 100 and 125kW, real traffic data and two types of traffic conditions – peak hour and free flow – to evaluate the performance of DWC systems.
A dynamic wireless power transfer functional layout
Keyword: Wireless charging on agenda