Wireless charger reaches new heights, powering up multiple devices

Most phones, tablets and laptops still rely on plugs and sockets, with wireless charging requiring devices to be kept in close contact with a charging pad. New technology developed at Aalto University could be a key step towards true wireless charging for consumer electronics.

While many researchers are working on “free-position wireless charging” (which would allow devices to be moved from set charging points) the most common solutions involve complex control and detection functions. A transmitter must first detect a device presence and position to be able to charge it. This is usually achieved with cameras or sensors, adding bulk and cost to the device.

The new wireless charging device takes an entirely different approach by creating power transfer channels in all directions around it and automatically tuning channels when receiving devices are in motion. Multiple devices equipped with a complementary receiver can simultaneously be charged or directly power their functions without being in physical contact with the device or even being moved to a specific plane.

The effect is made possible through the design of the coils in the transmitter. By winding the coils in a certain way, they created two electromagnetic fields: one pointing outwards and the other around. These fields couple the receiver and transmitter for power transfer.

“What sets this transmitter apart is that it’s self-tuning, which means you don’t need complex electronics to connect with receivers embedded in devices. Since it self-tunes, you can also move the device freely within a wide charging range,” said Dr Prasad Jayathurathnage.

The transmitter is highly efficient at 90 per cent at up to 20cm separation, but continues to work at longer distances at lower efficiency. The peak-efficiency range could expand further as the technology is refined. Jayathurathnage explained: “For now, the maximum range at peak efficiency is dependent on the size of the transmitter and receiver. With the right engineering, we could shrink them down.”

Next, safety tests will be needed to confirm that the electromagnetic field generated by the transmitter is not harmful to humans. Once deemed safe, bringing the technology to product would cut hassle in a world increasingly dependent on electronic devices.

“True wireless charging means more personal freedom. You won’t have to worry about where you put your phone or whether you remembered to plug it in,” said Jayathurathnage.