Qi wireless charging
The Qi logo, consisting of a lowercase "q" with a semicircle-esque "i" with a circle on top
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| Status | Active |
|---|---|
| Year started | 2008 |
| First published | 2008 |
| Latest version | 1.2.3 |
| Organization | Wireless Power Consortium |
| Committee | Wireless Power Consortium |
| Domain | Inductive charging |
| License | Open standard |
| Copyright | Logo and trademark |
Qi (pronounced /tʃiː/ CHEE; from the Chinese word qi, "energy flow") is an open interface standard that defines wireless power transfer using inductive charging over distances of up to 4 cm (1.6 inches), and is developed by the Wireless Power Consortium. The system uses a charging pad and a compatible device, which is placed on top of the pad, charging via resonant inductive coupling.
Mobile device manufacturers that are working with the standard include Apple, Asus, HTC, Huawei, LG Electronics, Motorola Mobility, Nokia, Samsung, BlackBerry, and Sony.
First released in 2008, the Qi standard had by 2016 been incorporated into more than 140 smartphones, tablets and other devices.
Under the Qi specification, "low power" inductive transfers deliver power below 5 W using inductive coupling between two planar coils. These coils are typically 5 mm apart but can be up to 40 mm and possibly farther apart.
Regulation of the output voltage is provided by a digital control loop where the power receiver communicates with the power transmitter and requests more or less power. Communication is unidirectional from the power receiver to the power transmitter via backscatter modulation. In backscatter modulation, the power-receiver coil is loaded, changing the current draw at the power transmitter. These current changes are monitored and demodulated into the information required for the two devices to work together.
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