Wireless charging is not just about convenience. For electric buses, it can enable operators to prolong battery life, to achieve the same range with a smaller battery pack, and to charge the same number of vehicles with fewer charging stations, as a Momentum Dynamics exec (among others) explained to Charged.

The electrification of bus fleets is advancing swiftly in Europe, particularly in Switzerland, where a startup called Winduction, a spin-off from the respected technical university ETH Zurich, is taking a novel approach to inductive charging.

“We believe that electric buses can be operated much more cheaply if they are charged wirelessly and regularly during operation,” says ETH graduate and Winduction CEO Laurin Schwitter.

Most inductive charging systems transfer electricity from a coil in the ground to a second coil on the vehicle’s undercarriage—but there’s one weakness in this approach. The distance between the road and the undercarriage is relatively large, and varies from one vehicle model to another. This distance is important, as the efficiency of energy transfer decreases with increasing separation.

The three founders of Winduction believe they’ve found a better way. “In any vehicle, the only thing that’s always in contact with the ground are the wheels,” says Winduction CTO Sylvain Fricker.

The company’s system includes a set of induction coils housed in a ground plate set into the road surface, as in a typical setup. The second group of coils, however, is integrated into a specially developed bus tire.

“We minimize the transmission distance between the road and undercarriage by placing coils inside the wheel,” says Fricker.

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