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New Dynamic Charging Technology for EVs Being Tested in Sweden

published: 2018-04-23 14:07

Electric vehicle (EV) owners in Sweden rejoice as the country’s Transport Administration has just opened a stretch of road integrated with a charging rail that can supply power to the EVs traveling on it. This “electric road,” which is two kilometers in length and located just outside Stockholm, has the potential to realize the concept of dynamic charging for EVs.

The technology behind the electric road, also known as the eRoadArlanda project, is the charging rail or trench that is installed in the middle of the road. The trench works with a specially designed charging system that is attached to the underside of the EV. The charging system has a retractable, moveable arm that serves as the contact responsible for transferring the electricity from the trench to the EV battery. When the cruising EV is kept on the center of the electric road and on top of the rail, the contact arm lowers into the trench and begins the charging process. In instances such as making turns or lane changes, the contact arm automatically folds back up. The system at the same time calculates how much power the EV has taken from the electric road and accordingly charge a usage fee to the driver.

There are obvious safety concerns with this design. First, pedestrians may get electric shocks. Second, the gap within the rail (i.e. the conducting trench) may cause accidents for motorcycles and bicycles. However, the developers of eRoadArlanda stated that the conductor are embedded deep under the ground. Also, the electric road is divided into sections. Each section is powered only when a vehicle is moving on top of it. Hence, the surface of the road is very safe for pedestrians. As for motorcycles and bicycles, they will not get stuck on the rail because the gap of the conducting trench is very narrow.

Furthermore, the official website of the project states that the bad weather such as rain or snow will not affect the charging performance of the electric road. The rail features heating coils that melt the ice and snow. It also has drainage holes on the sides to remove rainwater. The same drainage holes can also remove gravels and other small debris in the trench (plus the retractable contact arm can also push out obstacles). Larger obstacles like rocks are too big to get caught in the gap of the rail.

The eRoadArlanda project is supported by the Swedish government and managed by a consortium of public and private interests. The two-kilometer long electric road will connect Stockholm Arlanda Airport to the nearby Rosersberg logistics area. The road currently serves as a test track for the charging system that is equipped in modified trucks owned by the delivery company PostNord AB.

Hans Säll, chief executive of the consortium, pointed out that the charging rail is compatible with all types of roads and vehicles. Furthermore, the per-kilometer cost of the electric road is just one-fiftieth of that of an urban tram line. Sweden is currently pushing for the electrification of its highway network.

According to the project developers, EVs can now travel more than 45 kilometers without recharging. At the same time, the distance between two highways in Sweden are typically less than 45 kilometers. This means that electrifying 20,000 kilometers of highways at a cost of 80 billion Swedish krona (or 278.9 billion New Taiwan Dollar) would meet the needs of Swedish EV drivers. The developers of eRoadArlanda further estimates that only a three-year period is needed to recoup the total cost of the highway electrification scheme.

Ultimately, the goal of the eRoadArlanda project is to expand the basic infrastructure for EVs and provide more charging options. If the project is successful, then we may see changes in the development of EVs. The adoption of dynamic charging could lead to smaller battery and quicker charging while addressing the problem of range anxiety.

 (The above article is an English translation of a Chinese article written by Daisy Chuang. The credit of the image at the top of the article goes to the eRoadArlanda consortium.)

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