JAPAN Toshiba Corporation has developed a fast, cable-free contactless charger for electric vehicles and is field testing it on an 8.9m electric bus that sees regular use on high-speed expressway journeys.
The 45-seat vehicle is powered by a long-life, high-output SCiB, Toshiba’s advanced lithium-ion rechargeable battery, and is making regular trips between All Nippon Airways’ facilities in Tonomachi, Kawasaki and Haneda Airport in Tokyo. The 11km journey tests the performance of the bus under various traffic conditions, and enables Toshiba to verify the convenience and practicality of contactless charging along with its contribution to reducing carbon dioxide (CO2) emissions.
The contactless charger, designed in collaboration with Professor Yushi Kamiya of the Faculty of Science and Engineering at Waseda University, replaces conventional electromagnetic induction with a magnetic resonance system that is installed in the ground under the bus. The system is easy to operate with charging starting once the driver pushes a button on the dashboard. As it is cable-free, all risk of electric shock is eliminated.
Electromagnetic induction requires close alignment with the battery. A small distance separates the charge transmitting pad from the receiving pad. The charge pad of Toshiba’s system and the SCiB battery can be misaligned by as much as 20cm along the width and 10cm along the length, and can be as far apart as 10cm. Tests have verified that the system’s radio emission level meets limit regulations and do not interfere with radio signals of nearby equipment.
The SCiB battery installed in the bus shows almost no fall-off in performance even after 15,000 quick charge and discharge cycles. It is well suited for use powering shuttle buses around tourist sites and airports where heavy use is combined with frequent, fast charging. It takes only 15 minutes or so to charge it to a level necessary for the electric trial bus to run one-way between the test sites.
