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  • Author Author: johnsocm
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Final Reverse Engineering - Powermat...Non Qi Enabled Version

johnsocm

Hello World,

 

I wanted to explore one final design before I create my final PCB for the BeagleBone BeagleBone Qi Cape and Raspberry Pi - Qi Pi.

 

I was very fascinated to see that out of all the designs we explored, the Powermat for some strange reason used a coil implemented on a PCB. This design works really well but for distance wise, I am only able to charge a device that is sitting directly on the Powermat. I am not able to charge anything that is raised up even a milimeter. The Wurth Coil is very powerful and definitely the coil I will be using in my design. I am not quite certain if this PCB coil would work better in a Qi environment rather than a inductive standard charger environment. I could test this PCB to see how well it performs with the eval kit, but I am assuming it will not be as good as the coil from Wurth as the Wurth Coil has two layers of coil and thicker diameter wire.

 

Here are pictures of the transmitter side of the iPhone 3GS Powermat.

 

Transmitter:

imageimage

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Circuit Board Coil:

image

Does not power Qi Devices:

image

Very slim design!

image

 

Thank you,

Chad

  • Hi Chad,

    This may not be the only factor affecting performance.

    The Würth coil is made from Litz (literally "braided/stranded") wire to establish efficient magnetic coupling with efficiencies of up to 75%.

    It is not unusual for Litz wire to consist of thin and parallel conductors bound together.

     

    This greatly differs from the single large conductor used with the PCB coil.

  • Hey Chad that is quit interesting! I didn't expect there to be such a big difference in the Energizer and the Powermat. It seems that Powermat is already on that market since quit some time...i would even say sine before QI.

     

    There you can clearly see that it is nice to have this QI standard now! Great work Chad!

  • Hi Chad,

     

    I am not surprised at your findings.  Most manufacturers build a system adequate for the job, but at the minimum cost.  The days of overengineering products is mostly over.

     

    The powermat was clearly built of a single purpose device.  I suspect the designers gave it just enough capability to do the job.

     

    The Wurth components are intended for a more general purpose use, so I would expect them to have more capability.  After all, you need to provide a robust component to encourage engineers to embed your device in new applications.

     

    Your reverse engineering has provided a lot of useful information to anyone looking into existing and future wireless power transfer applications.

    After all, its the information that is important.  The components will continue to evolve over time.

     

    Thanks

    DAB