Wireless transmission of power along a railway track

[Edwina Lee]

China is embarking on developing high speed railways that use wireless transmission of power, thus reducing the need to replace the sliding electrode which needs frequent replacement.
The project is aware of the health & safety issue, of course. It also implies that they have already come to the conclusion that it is not infeasible. In fact, likely to be feasible.

Would you like to speculate how this might work?

 

[jerromyjon]

Nikola Tesla first developed the technology a long time ago. The wireless device chargers available use the same basis, I believe. They simply convert the electricity to electromagnetic radiation which travels through the air with very little resistance. When the radiation arrives at a receiver it is converted back into electricity.
http://en.wikipedia.org/wiki/Wireless_power

 

[berkeman]

China is embarking on developing high speed railways that use wireless transmission of power, thus reducing the need to replace the sliding electrode which needs frequent replacement.
The project is aware of the health & safety issue, of course. It also implies that they have already come to the conclusion that it is not infeasible. In fact, likely to be feasible.

Would you like to speculate how this might work?

Welcome to the PF.

Do you have a reference with technical information about that project? Probably coils are used under the cars to transfer AC energy into the train, but yeah, what frequency are they using and how much shielding is planned for the undersides of the cars...?

 

[jerromyjon]

I would imagine they would use a linear transmission method and use a "transformer" car. I also imagine high-speed will necessarily be maglev?

 

[tech99]

China is embarking on developing high speed railways that use wireless transmission of power, thus reducing the need to replace the sliding electrode which needs frequent replacement.
The project is aware of the health & safety issue, of course. It also implies that they have already come to the conclusion that it is not infeasible. In fact, likely to be feasible.

Would you like to speculate how this might work?

One technique may be the linear induction motor, which can provide propulsion as well as magnetic levitation. It uses a sequence of coils along the track, which are driven with a phase difference like an ordinary induction motor, so as to provide a moving field. The technique was invented, I believe, by Professor Eric Laithewaite, of the UK, in the 1960s. Such a system would, of course, be very costly. The more economical way of implementing it is to use the magnets on the train and have overhead power.

 

[Edwina Lee]

Jerromyjon, Berkeman, tech99, Thanks for your response.

I don't have technical information other than from general news channels. (SCMP.COM is a Hong Kong english paper. You can read a limited number of their articles for free by registering.) Their article gives some details about the challenges:-
http://www.scmp.com/lifestyle/techn...l-track-china-seeks-develop-world-first-power

 

[stedwards]

Per the article,

"Sun said his system could "beam" more than 13,000 horsepower, or 9.7MW, to a train using resonant magnetic induction, enough to easily propel a fully loaded subway train or a high-speed train at 350km/h or more."
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http://en.wikipedia.org/wiki/Resonant_inductive_coupling (same thing)

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