Wireless power transfer achieved at 5-meter distance

With a maximum output power of 209W at 20kHz, the Dipole Coil Resonant System can charge 40 smartphones simultaneously, even if the power source is 5 meters away.

Article  |  Fall 2014

A new remote power delivery mechanism was developed in which power is wirelessly transfer power over two times farther, and the transferred power is over three times larger than the conventional Coupled Magnetic Resonance System (CMRS) that was developed by MIT.

To overcome the demerits of the CMRS, the team introduced the Dipole Coil Resonant System (DCRS), which can provide 209 W of power in an extended range of inductive power transfer with up to a 5-meter distance between the transmitter and receiver coils.

An optimally-designed coil structure that has just two magnetic dipole coils (transmitter and receiver coils), and with a scalable and slim  size of 3 m in length, 10 cm in width, and 20 cm in height, the DCRS is significantly smaller than the CMRS. The DCRS is also 20 times more robust against environmental changes and works well at a low frequency of 100 kHz, which represents a major step forward in terms of efficiency.

Similar to Wi-Fi zones, which are found everywhere today, we will eventually develop Wi-Power zones in places such as restaurants and streets where electric power will be provided wirelessly to electronic devices.

If this technology is adapted to nuclear power plants, it will be very helpful to remotely supply electric power to essential instrumentation and control equipment, enabling plant employees to properly respond to emergencies like the one occurred at the Fukushima Daiichi Nuclear Plant.

* Dipole Coil Resonance System (DCRS): It is composed of an optimally-designed coil structure with ferrite core rods at the centers of the coils. The structure has two magnetic dipole coils, a primary one to induce a magnetic field and a secondary one to receive electric power. A resonance circuit is used in the primary and secondary coils to transfer such a large power, and the system has a low Q factor of 100, which promotes a robust wireless power transfer system against 1% changes in the resonance frequency condition. An optimized stepped core structure is adopted to reduce the amount of coils by two times, and there are no practical problems to transfer the power even if people or metal fragments are nearby.

Featured in season 1, episode 4 of “Around the Carillon”, the official KAIST podcast, available online at http://www.kaist.edu/html/en/news/podcast.html