Wireless Power Transmission
A new method to wirelessly transfer power was developed by a Korean research team.
The Korea Advanced Institute of Science and Technology (KAIST) announced on April 17 that a research team headed by Rim Chun-taek, Associate Professor at the Department of Nuclear & Quantum Engineering of KAIST, succeeded in wirelessly transmitting 209W from 5m away. That amount of electricity can charge 40 smartphones at the same time, operate five electric fans, or run a large LED TV.
A technique to wirelessly charge small electronic devices such as electric shavers or smartphones at a very short distance has already been commercialized, but it is the first time to successfully transfer power from a distance of 5m. In 2007, a research team at MIT successfully transferred 60W up to 2.1m with a coupled magnetic resonance system (CMRS). However, the method was not able to be commercialized after its development since the structure of the coils was complicated and bulky. On top of that, the technique was not efficient, because it only operated above 10MHz.
The Korean research team was able to overcome the shortcomings of existing wireless power transmission tech with a dipole coil resonance system (DCRS). The team decreased the number of transmission and reception coils to only two, or a dipole structure. They also reduced the size of coils using ferrite cores. Thanks to low-frequency variation, the new technique is 20 times less affected by a change in the surrounding environment than conventional technologies. The newly-developed method is easy to be commercialized as well, as it can operate at 100KHz.
Previously, the team successfully transferred 10W from a distance of 7m after using the tech for the development of an emergency power source for a measuring instrument of a containment building, in partnership with Korea Hydro & Nuclear Power. At the time of the Fukushima nuclear accident, power supply to a measuring instrument was lost, and thus it was not possible to assess the damage, which worsened the situation. In that case, a wireless power transfer method could have been utilized.
Professor Rim explained, “The new technique can transmit power more than twice as far and three times as much as traditional methods. So, it contributed to the earlier commercialization of the long-distance wireless power transmission technology.” He added, “The method is less efficient than using electrical cords. However, our team is intensifying efforts to develop a technique that can enable people to wirelessly use electronic devices without chargers when they approach a specific area like a Wi-Fi zone.” The professor concluded by saying, “I think that the new tech can be used in nuclear power plants in the nation once it passes tests by KEPCO Engineering & Construction Company.”
The research findings were first published online in March in The Institute of Electrical and Electronics Engineers (IEEE) Transactions on Power Electronics published by the Institute of Electrical and Electronics Engineers, Inc.