On April 17, Professor Chun-Taek Rim and his research team from the Department of Nuclear & Quantum Engineering announced that they had successfully transferred 209 Watts (W) wirelessly over 5 meters (m) using dipole coil resonance system (DCRS). With this amount of power, 40 smartphones can be charged, four fans can be operated simultaneously, or even a large light emitting diode (LED) television (TV) can be turned on.

▲ Professor Rim and his team transferred 209 W wirelessly over 5 m using DCRS

 

Long range wireless power transfer technology has received much attention after Massachusetts Institute of Technology successfully transferred 60 W over 2.1 m using coupled magnetic resonance system (CMRS) back in 2007. However, current CMRS technology requires a complex coil structure (input coil, transmission coil, reception coil, load coil), bulky resonant coils, and high operating frequency (over 10 megahertz (MHz)), resulting in low transfer efficiency and large heat generation. Thus, commercialization had not been successful though it has been six years since its development.

The research team led by Professor Rim lowered the number of coils required to two (transmission coil and reception coil) and reduced the volume by using high frequency magnetic materials (ferrite core) with optimized dipole structure. It is 20 times stronger against environmental changes, performs well at 100 kilohertz (kHz), and is evaluated to be more commercial.

The research team is working together with Korea Hydro & Nuclear Power Company to develop an emergency power supply to remotely supply electric power to essential equipment during nuclear power plant crises. During the Fukushima nuclear power plant crisis, the power to detecting instruments was cut off, resulting in more damage than had the instruments worked. If wireless power transfer technology is applied to nuclear power plants, it can greatly aid in planning for protective measures. The research team at KAIST applied DCRS technology and successfully transferred 10 W over 7 m last March.

Professor Rim said, “We were able to increase the transfer range over two times and transfer power over three times, shortening the time required for commercializing wireless power transfer technology.” He also added, “Wireless power transfer has lower power efficiency and is more expensive compared to direct connection by an electrical wire. However, like Wi-Fi zones, our goal is to allow users to conveniently use their electrical devices when they enter a specific area without requiring chargers.”

The research was funded by Ministry of Trade, Industry & Energy and the results were published in the March issue of The IEEE (Institute of Electrical and Electronics Engineers) Transactions on Power Electronics.

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