How To Implement A 5-W Wireless Power System

Focus:

The development of an industry standard for wireless power transmission called Qi has made wireless battery charging a practical technology for handheld products. This standardization enables interoperability and has encouraged the development of chipsets like bqTESLA, which provide the core functionality for the wireless power transmitter and receiver. However, to complete the implementation of a wireless charging system, designers must understand additional factors related to external component selection, physical design, and thermal analysis. This article provides a brief introduction to the Qi standard and why it was developed. It then explains principles of operation behind Qi-compliant 5-W wireless power transmission (using the bqTESLA solution as an example) including the method of detecting a Qi-compatible device on the charging pad. Selection of the magnetic components (transmit and receive coils) is briefly discussed along with a description of the coils provided in the TI Evaluation Module (EVM) for the bqTESLA system. Efficiency measurements for the EVM are discussed and methods for selecting receive-side capacitors are explained.

What you’ll learn:

• How to understand operation of a Qi-compliant wireless power system
• How to understand the factors that influence wireless power system efficiency
• How to select magnetic components and receive-side capacitors for a Qi-compliant wireless power system

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Author & Publication:

Upal Sengupta and Bill Johns, Texas Instruments, Dallas, Texas, How2Power Today, Jul 27 2011

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