Proximity Charging System Frees Korean Electric Tram From Overhead Cables
By John O'Dell March 12, 2010
The first electric tram with batteries that are continually recharged electromagnetically from power cables buried in the ground began operating in Seoul's zoo this week, providing what the vehicle's builders say is a prototype for electric-powered buses and trams that can operate without overhead cables.
Working with the city of Seoul, the Korean Advanced Institute of Science and Technology (KAIST) - a science and engineering graduate school about 100 miles south of the South Korean capital city - built what it calls an online electric vehicle (OLEV), which replaced a trackless combustion-engine train used to ferry visitors through zoo.The three-car train runs about 1.4 miles through the zoo.
The underground cables are interspersed in strips throughout the route to continually "update" the tram's battery charge as it passes over them.
KAIST said in a statement that by avoiding the need to bury a continuous cable along the entire route, the systems makes it easier to retrofit electric bus and trolley lines by minimizing disruptive road work. The zoo tram cable sections have a total length of just 20 percent of the 1.4-mile route.
With power traveling between the train and cables buried about a foot underground, the tram's batteries are always either being sent power to propel the vehicles or being recharged.
With such a system in place, the train carries a battery that's just one-fifth the size of a typical EV battery and doesn't need the overhead power wires typically found with other tram or bus systems, according to KAIST.
Danny King, Contributor
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