Toshiba has developed a fast, wireless charger for electric vehicles, and will field test it on a medium-sized EV bus designed to handle the power demands of regular high-speed journeys on expressways. Field tests will continue until December.
The 45-seat bus is powered by a long-life, high-output SCiB, Toshiba’s advanced lithium-ion rechargeable battery, and will make regular trips between All Nippon Airways Co. Ltd. facilities in Tonomachi, Kawasaki and Haneda Airport in Tokyo.
The 11-kilometer journey will test the bus and its performance under various traffic conditions, and will allow Toshiba to verify the convenience and practicality of contactless charging, along with its contribution to reducing carbon dioxide (CO2) emissions.
The wireless charger, designed in collaboration with Professor Yushi Kamiya of the Faculty of Science and Engineering at Waseda University, replaces conventional electromagnetic induction1 with an innovative and highly promising magnetic resonance2 system that is installed in the ground, under the bus. The system is easy to operate; charging starts once the driver pushes a button on the bus dashboard. As it is cable-free, all risk of electric shock is eliminated.
Electromagnetic induction requires close alignment with the battery, and a small distance separating charge transmitting pad and receiving pad. Magnetic resonance is much more forgiving: The charge pad of Toshiba’s system and the SCiB battery can be misaligned by as much 20cm along the width and 10cm along the length, and they can be as far as 10cm apart. 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 of the type installed in the test EV bus is rugged, reliable and has a long life, showing almost no fall-off in performance even after 15,000 quick charge and discharge cycles. It is highly suited for use on shuttle buses operating at locations such as tourist sites and airports, which must combine heavy use with frequent and fast charging. It takes only 15 minutes or so to charge SCiB to a level necessary for the EV bus to run one-way between the test sites.
The battery also delivers high output that, combined with improvement in performance of drive components allows the bus to achieve a top speed surpassing that required for safe operation on expressways.