Toshiba wireless charger completes year-long field testing with electric buses

Electric Bus with Toshiba's

Toshiba, in cooperation with Waseda University, has completed a year-long field test of electric buses equipped with its wireless rapid rechargeable battery system. In the test, a small and a medium-size bus, both customized to run on Toshiba’s SCiB batteries (the medium-size bus used a 52.9 kWh battery pack), provided regular service between All Nippon Airways facilities in Kawasaki and Haneda Airport in Tokyo for a year.

The test showed that replacing legacy diesel buses with the e-buses could cut CO2 emissions by up to 60% for the medium-sized bus and by up to 42% for the small bus.

Toshiba’s 44 kW wireless system feeds power to the battery when the bus is parked over charger pads. It uses a magnetic resonance system operating in the 85 kHz band, the proposed international standard. Toshiba says it selected magnetic resonance because it doesn’t require the transmitting and receiving pads to be as precisely aligned as systems that rely on electromagnetic induction. The charging pad in Toshiba’s system can be misaligned by as much 20 cm, and the two pads can be as far apart as 10 cm.

Electric Bus with Toshiba's Wireless Charger 2 copy

The SCiB battery showed almost no reduction in performance after 15,000 quick charge and discharge cycles. Toshiba found it to be highly suited for use on shuttle buses operating at locations such as tourist sites and airports, which must combine heavy use with frequent fast charging.

“I’m convinced that wireless rapid charging will help boost the use of electric buses,” said Dr. Osamu Hori, Director of Toshiba’s R&D Center. “Toshiba will continue research and development of convenient charging technologies.”


Source: Toshiba

  • James Heires

    The statement “The charging pad in Toshiba’s system can be misaligned by as much 20 cm, and the two pads can be as far apart as 10 cm” sounds like a rather tight tolerance to me. Does this mean the charging receiver on the vehicle needs to be just 10cm from the transmitter on the ground? And the vehicle receiver needs to be within 20cm of the transmitter pad center to center? Maybe this technology would benefit from a looser spec?

    • Electric Bill

      James, 20 centimeters is nearly eight inches… that is a fairly significant gap, which a driver with a few hours of practice should be able to handle without difficulty, especially if aided by some electronic, visual or physical assistance— such as that which Tesla autonomous cars have.

      Have you ever seen the videos of the SpaceX boosters that are twenty stories tall, parking themselves spot-on, on “Of course I still love you”, bobbing and rocking at sea—a barge that is far less in width than the height of the rocket? If those massive boosters can manage THAT while dealing with sidewinds and ocean currents, certainly some electric buses can handle a couple of inches of leeway easily.

      • James Heires

        Thanks, Electric Bill, I know that 20cm is about 8 in! That’s still pretty close – keep in mind, we’re not dealing with a rock star like Elon Musk with Toshiba – far from it…

  • MikeH

    Does anyone know how “magnetic resonance” is different from “electromagnetic induction”? It seems like either technology is likely to induce high magnetic fields when transferring 44kW of power. These magnetic fields can be inefficient if other ferrous metals are nearby and could also affect personal electronic devices as well as vehicle electronics.

    • Electric Bill

      If it were able to present the kinds of problems you mention, a year of real-life use with actual customers would have exposed it… which, of course, is why you have such testing.