Wireless electric vehicles take Gumi City citizens on 24-km roundtrip
As Elon Musk presents his 57-page Hyperloop plan and demonstrates a fast battery-swapping station for the Tesla S, the Korea Advanced Institute of Science and Technology (KAIST) is pursuing a less flashy but nevertheless impressive transportation innovation. As a result, Gumi City in South Korea, as of August 6th, is providing its citizens with Online Electric Vehicle (OLEV) public-transportation services. Two OLEV buses will run an inner-city route between Gumi Train Station and In-dong district, for a total 24-km roundtrip.
The vehicles might better be described as “no line” or “line free”—they require no pantographs to obtain power from overhead electric wires; instead, they employ what KAIST calls “Shaped Magnetic Field in Resonance” (SMFIR) technology, which enables electric vehicles to transfer electricity wirelessly from the road surface while moving.
As KAIST puts it, “Power comes from the electrical cables buried under the surface of the road, creating magnetic fields. There is a receiving device installed on the underbody of the OLEV that converts these fields into electricity. The length of power strips installed under the road is generally 5% to 15% of the entire road, requiring only a few sections of the road to be rebuilt with the embedded cables.”
Each operating bus receives 20-kHz, 100-kW power at an 85% maximum power transmission efficiency rate while maintaining a 17-cm air gap between the underbody of the vehicle and the road surface.
KAIST says each vehicle complies with the international electromagnetic fields (EMF) standards of 62.5 mG, within the margin of safety level necessary for human health. In addition, the road has a smart function that distinguishes OLEV buses from regular cars—switching on the power strip when OLEV buses pass along, but switching it off for other vehicles, thereby minimizing EMF exposure and standby power consumption.
Dong-Ho Cho, a professor of the electrical engineering and the director of the Center for Wireless Power Transfer Technology Business Development at KAIST, said, “It’s quite remarkable that we succeeded with the OLEV project so that buses are offering public transportation services to passengers. This is certainly a turning point for OLEV to become more commercialized and widely accepted for mass transportation in our daily living.”
Previously, at a smaller scale, OLEV trams (at an amusement park in Seoul) and shuttle buses (at the KAIST campus) have operated successfully.
After the successful operation of the two OLEV buses by the end of this year, Gumi City plans to provide ten more such buses by 2015.
In addition, Bombardier Transportation plans to test its electric transit technology on buses in Montreal and on a route in the German city of Mannheim. The company's Primove technology is designed to allow buses to be charged by underground induction stations when they stop to let passengers on and off—rather than while moving, in the case of the OLEVs. The company previously tested a version of its Primove system on an 800-m branch of the Augsburg, Germany, tram network.