Wireless power technology embraces user-friendly features

Focus:

This short article discusses two useful features of wireless charging systems—foreign object detection and dynamic power limiting—which are being implemented in chipsets for Qi-compliant wireless power systems (a.k.a. wireless charging systems). Foreign object detection is a safety feature intended to prevent heating of metallic objects in the vicinity of the transmitter. By detecting losses above a calculated threshold for the expected systems losses, a wireless power system can detect heating of foreign metallic objects and stop power transmission. Meanwhile, dynamic power limiting is a user-convenience feature that allows wireless charging at a reduced rate when the transmitter is being powered from a current-limited 5-V supply such as a USB port or ac adapter. This concept and their implementations are discussed. Prior to discussing these features, the authors explain the basic operation of a wireless power system.

What you’ll learn:

• How to understand the operation and benefits of foreign object detection and dynamic power limiting in wireless charging systems
• How to understand the different sources of loss in wireless power systems

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Author & Publication:

Pearl (Ke) Cao and Vladimir A. Muratov, Texas Instruments , ECN, Oct 12 2012

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