Transcript
Thanks to electrical engineers at the University of California at San Diego, a wireless charger compatible with multiple brands of consumer electronics devices is becoming a reality, according to research published in the journal IEEE Transactions on Power Electronics.
Researchers have developed a dual-frequency wireless charging platform that can be used to charge multiple devices (smart phones, smart watches, laptops, and tablets) regardless of which wireless standard, or frequency, each device supports.
To date, this is the only multi-standard wireless power transmitter that's been shown to operate simultaneously at two different frequencies with high efficiency, according to Patrick Mercier, a professor in the Department of Electrical and Computer Engineering at University of California, San Diego.
The recent proof-of-concept study not only presents a "universal wireless charger" that can deliver power to multiple devices concurrently, it also addresses an issue that afflicts existing wireless technology: incompatibility between the three competing wireless standards in today's market.
Each wireless charger so far supports either the Qi, Powermat, or Rezence standard and will only work with devices that support the same standard. These three standards operate at different frequencies: Qi and Powermat operate at around 200 kilohertz, while Rezence operates at 6.78 megahertz. In order for a single charging device to support multiple standards, it needs to operate across these very different frequencies.
A wireless charger's ability to operate at a particular frequency depends on its transmitter coil. Wireless charging generally requires the charger's transmitter coil to send a high-power signal out to a compatible receiver coil in the device to be charged.
Existing wireless chargers are typically built with a transmitter coil that's optimized to work at only one frequency. But as a consequence, the chargers are extremely inefficient at other frequencies.
As a result, wireless charging technology is ripe for a battle similar to the one that took place between Blu-ray and HD DVD. A battle between incompatible wireless standards could cripple the field until a winner emerges.
To help avoid that scenario, the team developed a wireless technology that is universal and supports all of these standards so it won't matter which standard your device supports.
To achieve this, the team built a charging platform capable of simultaneously operating across the frequencies supported by all three wireless power standards. The prototype is a thin, rectangular box that contains two transmitter coils: an inner coil optimized to operate at a frequency of 200 kilohertz, and an outer coil optimized to operate at 6.78 megahertz.
One of the features of this design is that the coils lie in the same plane, allowing for a compact size. The platform is just big enough to fit two smartphones side by side.
Another important feature of the prototype is a filtering circuit that the researchers designed to prevent the coils from interacting with each other and causing efficiency losses. The researchers then tested the charging platform using the two receiver coils, which served as models for two different smartphones.
Engineers demonstrated that the charging platform was able to deliver power to both receiver coils at the same time at efficiencies ranging from 70 to 80 percent. The receiver coils were also able to receive power regardless of where they were placed on the charging platform.
The researchers have filed patents on this technology and are looking for commercial partners to help bring the universal wireless charger into the market.
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