When it’s pouring rain, a driver who has to connect a thick, unwieldy cable between their electric car and a charge spot is sure to get soaked to the skin. But sometimes there’s no alternative – the battery is empty.
Researchers from the Fraunhofer Institute for Wind Energy and Energy System Technology IWES offer an alternative—wireless charging.
Using wireless inductive systems to charge a car involves transmitting energy through the air, or, more precisely, through a time-varying magnetic field. The technology is essentially based around two coils, with one built into a road, a parking space or a garage, and the other fitted to the underbody of the car. In conjunction with suitable capacitors, these coils form a sort of resonant “antenna system for energy transfer.” The nearer the two coils are to each other, the more efficiently the energy is transferred.
The cost-effective charging system achieves high levels of efficiency across the whole power range, from 400 watts to 3.6 kilowatts, while the car and the charging coil can be up to 20 centimeters apart. Fraunhofer researchers presented their prototype at the IAA International Motor Show in Frankfurt last September 15 to 18, 2015
Electric cars have only a limited range. In the future, however, it will be possible to charge cars while they are moving: researchers at the Fraunhofer Institutes for Manufacturing Technology and Advanced Materials IFAM and for Transportation and Infrastructure Systems IVI have constructed a 25-meter-long test route along which coils have been set into the road. The project was supported by the German Federal Ministry of Transport and Digital Infrastructure and two further project partners. It was a success: the FreccO demonstrator, a sports car converted into an electric vehicle, managed to travel the strip at a moderate speed while simultaneously charging its battery.