Pulling Power from the Road

This article presents an overview of charging technology called Shaped Magnetic Field in Resonance (SMFIR). It has been developed by a team of engineers and technologists at the Korea Advanced Institute for Science and Technology. An all-electric bus developed in Korea recharges its battery when it travels over electric coils buried at intervals along its route. The concept is called on-line electric vehicles, and the heart of OLEV technology is the transfer of enough electricity across gaps of up to 10 inches to power a fully loaded bus. Specifically, underground cables transfer power from the electrical grid to drive motors and on-board batteries via pickups beneath the OLEV bus bodies. The OLEV system wirelessly charges a bus, stopped or in motion, for continuous operation. SMFIR transfers rely on electromagnetic field resonance rather than inductive coupling. In SMFIR technology, the sending unit and the vehicle receiver resonate at 20,000 hertz.