Wireless Charging – The Final Frontier for the Mobile World

Thanks to researchers at the Korea Advanced Institute of Science and Technology (KAIST), in the city of Daejeon, South Korea, wireless charging is now a step closer. This latest advance in WPT (wireless-power transfer) means that smartphones, tablets, laptops and any other mobile device users may soon be able to recharge their gadgets’ batteries simply by being in a charging area, as they do now with internet connection via Wi-Fi. A sort of Wi-Power hotspot, if you will.

The KAIST research team, led by Professor Chun T. Rim of the Nuclear and Quantum Engineering Department, has been busy with WPT for some time now, but this most recent breakthrough means that they have been able to charge multiple devices at the same time. What’s more, the devices can be charged while they are pointing in any direction, in mid-air, in fact anywhere within half a meter from the power transmitter.

Now, after the fanfare at the beginning of this article, this news may be a letdown, but let’s put it into perspective. WPT is already used on smartphones, but the fact that wirelessly charging a Samsung Galaxy S6 offers no advantage over plugging it in. Moreover, plugging the phone in allows greater flexibility, as it can still be used. Charging wirelessly requires the Galaxy to remain in a fixed position, the receiver facing the transmitter, at no more than ten centimetres distance.

Professor Rim and his team have showcased technology that allows the charging of 30 smartphones, with an average one watt capacity, or five laptops, with a 2.4 watt capacity, simultaneously with their high frequency, dipole coil magnetic transmitter, no matter where they are in relation to it or at what angle they are at. This use of transmitting coils (Tx) and receiving coils (Rx) over all of a device’s three-axis positions and directions has been the major stumbling block with mobile applications for a while.

The technology consists of a Dipole Coil Resonance System (DCRS), developed by the KAIST team in 2014 for inductive power transfer over an extended distance, to induce magnetic fields. Only now, the DCRS is made up by placing two sets of Tx and Rx coils so they cross each other, causing their fields to rotate, which makes it possible for devices in any direction to be charged. Ferrite cores are used in the coils because they are almost completely unaffected by surrounding metal objects or squishy human bodies.

Luckily, the DCRS works in a low magnetic field environment. The level of magnetic flux is below the safety level set by the International Commission of Non-Ionizing Radiation Protection guidelines, so is okay for use in public.

Which all indicates that the days of charging hotspots, while not actually around the corner, are significantly nearer than before. As Professor Rim says, “(The) transmitter system is safe for humans and compatible with other electronic devices. We have solved three major issues of short charging distance…”, meaning that it won’t be long before the remaining issues are also dealt with.

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