Qi wireless power specification to standardize wireless charging
By Darren Quick
July 27, 2010
As the number of portable electronic devices we carry around has multiplied, so too have the chargers we need to keep them running. Over the last couple of years wireless chargers such as the PowerDisc and Powermat have started popping up to save users the hassle of dealing with a mass of charger cables, but these require specific adapters for the different devices being charged. A business alliance of 20 firms has banded together to form the Wireless Power Consortium (WPC) to develop open standards for wireless charging and has just finalized its Qi low power standard that is aimed at delivering wireless charging stations that can charge a range of compatible devices.
Based on the principle of magnetic induction, wireless charging technology allows power to be transmitted efficiently to devices over short distances – a couple of centimeters. The Qi low power standard delivers up to 5 Watts into wireless power receivers, which should be enough for most portable consumer devices, such as those charged via USB ports which max out at 2.5W.
The Qi power specification consists of three documents with the first currently available only to consortium members. However, it will be made publicly available as a free download on August 30, 2010. This document defines the interface for contactless power transfer between a power transmitter and a power receiver, based on near field magnetic induction between coils.
The test specification will be used to determine whether a product is compliant or not. Only products that pass muster and work according to the specification will be able to carry the Qi logo, which is designed to give consumers a simple way to determine which products will work together.
“Our customers will see the Qi logo and know: this product works with my other Qi products,” says Menno Treffers, a senior director of standardization at Philips who works with the consortium. “That promise holds if the logo is used on properly tested products. No Qi logo on products that don’t work! To protect Qi’s promise, the logo is trademarked and you need a license to use the logo. That license makes the use of the logo dependent on certification by an independent test lab.”
The WPC will begin certification testing of products this August, so products sporting the Qi logo could start appearing this fall.
Via ars technicaShare
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