Ordinarily, wireless chargers emit an electromagnetic field in just one direction, limiting the number of devices they can charge at once. An experimental new charger, however, produces a donut-shaped field, for the simultaneous charging of multiple gadgets.
First of all, there have been previous attempts at creating omnidirectional wireless chargers.
One approach has involved incorporating several transmitter coils, each one connected to its own power source. This is quite a complex solution, however, limiting its practicality for widespread use. Another approach changes the orientation of the charging field when devices are detected, but this is likewise a bit too complicated – and expensive – for commercialization.
Led by postdoctoral researcher Nam Ha-Van, a team at Finland's Aalto University has created what is claimed to be a simpler, less costly yet still highly functional alternative. At the heart of the system is a cylindrical power coil, the wires of which are wound in opposite directions on its top and bottom – a Z-shaped bridge connects those two ends.
"Since the current flows through these windings in opposite directions, they produce complementary magnetic fields," the university explained. "One field flows out from the middle of the cylindrical coil, around the top winding, and back in through the top; the other flows out from the middle, around the bottom coil, and back in through the bottom."
What results is a ring-shaped electromagnetic field, surrounding the middle of the cylindrical charger. Any electronic devices placed anywhere within that ring will charge efficiently, regardless of their orientation or position. And the strength of the field falls within the range that is considered safe for humans.
That said, the scientists are now working on boosting its power, while ensuring that it still meets safety standards.
A paper on the research was recently published in the journal IEEE Transactions on Industrial Electronics.
Source: Aalto University