Korea tests magnetically-powered train

[CHamilton]

Test run a success for wireless train
Progress still needed before technology can be commercialized

A locally developed wireless bullet train that runs without electric cords and instead uses magnetic technology was successfully test-driven Tuesday.

Although the technology is used in other types of vehicles, yesterday was the first time the wireless technology has been used to power a bullet train.

The Korea Railroad Research Institute tested the train on Tuesday on a 150-meter (492-feet) stretch of railway it built in Uiwang, Gyeonggi. The test moved the train at three to four kilometers per hour....

Electric buses have a capacity of about 100 kilowatts and trams have 180 kilowatts. Bombardier, a German train manufacturer, tested a light-rail tram network with the wireless battery technology in Augsburg in 2012. Korea has been using electric buses since last year in Gumi, North Gyeongsang, with locally developed wireless power-transfer technology created by the Korea Advanced Institute of Science and Technology and the rail institute.

But for the train, the Korean power-transfer technology carries and transfers a high volume of electricity, up to one megawatt, which is about 10 times that of electric buses and light rail trains. The train generates its own electricity as it runs.

A power inverter located near the railway sends electricity of about one megawatt through power-transfer coils installed in the middle of track. The electricity forms a high frequency magnetic field of about 60 kilohertz, by switching the polarization from plus to minus 60,000 times per second. As the magnetic field spreads, a line of current collector coils in the train above the power-transfer coil in the track absorbs the magnetic field and immediately transfers it into about 1.2 megawatts of electricity.

Each collector coil transfers 300 kilowatts and one train car has four coils. As the train travels along, the coils in the train and the line coils in the track generate energy simultaneously.

The power-transfer facility in the track can also carry 300 kilowatts, about 3.3 times more electricity than the coils used for light-rail trams.