Disney Research

Disney Research

Disney Research

Disney Research

Disney Research

Disney Research

Disney Research has achieved room-scale ubiquitous wireless power delivery. That is, Disney has created a prototype living room where 10 objects—a smartphone, a lamp, a fan, an RC car, and more—are powered wirelessly, no cables required. Unlike existing wireless power transfer solutions, which mostly require an object to be placed very close to a wireless charging pad, the objects in Disney's living room can receive power while freely roaming; you can walk into the room with a smartphone in your pocket and it will start charging.

The efficiency of the system is quite high, between 40 and 95 percent, depending on the receiver's position within the room. Furthermore, a surprisingly large amount of power can be pumped into the room—about 1900 watts—before the specific absorption rate (SAR), a measure of how much energy is absorbed by the human body, reaches dangerous levels.

The caveat, though, is that the room has to be purpose-built: the walls, ceiling, and floor, are all made of aluminium panels, and in the middle of the room there's a long copper pipe. Half way down the pipe a small section has been cut out, and in that gap is a ring of 15 capacitors.

Outside the room is a signal generator, which outputs a tone at 1.32MHz, and a power amplifier to boost the tone. A wire connects the 1.32MHz signal to the ring of capacitors that, with the copper pole, produce quasistatic cavity resonance (QSCR)—the sexy term that Disney uses to describe the underlying process that makes room-scale wireless power transfer tech possible.

When everything is turned on, and with the aluminium enclosure in place, the room is filled with a uniform magnetic field that can be tapped into with a coil of wire that's tuned to resonate at the same frequency. That receiving coil is connected to a couple of capacitors, and then onward to the object that is being wirelessly powered.

One interesting aspect of QSCR is that the magnetic field travels very slowly back and forth in a circular plane around the copper pole. This means if the receiver coil is parallel to that plane, it doesn't resonate—which is no good if you want to receive power while freely moving around the room. The solution was to create a new receiver design that consists of three orthogonal coils, so that one of them is always able to receive power.

The video above does a good job of explaining the preceding paragraph if, like me, you find it difficult to picture uniform circular planes and orthogonality in your head.

Safety-wise, the Disney researchers warn of a couple of issues. First, to stay within the SAR limits, no humans can stand within 46 centimetres of the copper pole—so you'd need some kind of mechanism that automatically shuts the system off if someone moved too close, or you need to put a decorative wall around the pole, right in the middle of the room.

Second, because a lot of power is stored within the metal enclosure, rather than dissipating into the environment, you can't just keep pumping in more power. In other words, you can safely beam 1900 watts of wireless power into the room—but only if there are devices in the room that are receiving and using about 1900 watts. The researchers note that about 100 watts of power can be continuously pumped into the room safely—but for larger amounts, a smarter system, with some kind of real-time power consumption tracking, would be required.

Finally, the researchers note that QSCR can scale up or down, from "small charging cabinets" to "large-scale warehouses potentially using multiple poles." They are also confident that QSCR won't always require a purpose-built metal-encased room, noting that the inclusion of a few windows and a door doesn't seem to "significantly alter" system performance, and that "modular panels or conductive paint" might one day be enough.

PLoS ONE, 2017, DOI: 10.1371/journal.pone.0169045 (About DOIs).

Listing image by Disney Research