An Introduction to Resonant Inductive Power Transfer

Focus:

This article explains the theory of operation behind series-resonant inductive wireless power transfer systems. Using simple circuit models, it explains the key relationships governing wireless power transfer and what conditions lead to maximum power transfer and maximum efficiency. A number of non-intuitive concepts are revealed and explained such as the fact that higher coupling factor (when coils are closer to one another) does not produce higher power transfer for a given load resistance, although it does produce higher system efficiency. Another non-intuitive idea explained here is that low values of load resistance maximize system efficiency. The advantages and disadvantages of voltage source driven systems (which protect against foreign metal objects) versus current-source driven systems (which can power multiple receivers) are also discussed.

What you’ll learn:

• How to understand the theory of operation of series-resonant inductive wireless power transfer systems
• How to maximize power transfer and efficiency in series-resonant inductive wireless power transfer systems

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Author & Publication:

Gianpaolon Lisi, Systems Manager, Kilby Laboratories, Kalyan Siddabattula, Systems Manager, Wireless and Low Power Charging, Texas Instruments, Magnetics Business & Technology, Nov 10 2015

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