Induction Charging

Sep 25, 2007 3 Replies

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frans wiersma 18 years ago

Hi,

I have a couple of questions regarding induction charging of consumer electronics.

I want find out whether it is possible to build a heavy induction charger into a relatively small consumer electronics device.

Demands:

- The charging system should work on 12V DC so a DC/AC converter will be necessary

- The charger should provide about 4 Volt, at 1A

- The charger should fit in a tube with an inner diameter of less than 1 inch

Questions

- What frequency is most suitable for the charger

- Is it possible to charge trough a 1 to 2mm thick aluminum tube? Secondary coil inside the aluminum tube, wound around a ferrite core, primary coil outside tube

- What would be the approximate size of the coils in the most ideal situation?

Any help appreciated!

Regards,

Frans Wiersma

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MooseFET 18 years ago

At that size, quite a wide range of frequencies can be used. Something like 100Hz would be the lower limit and somthing like 10MHz would be the upper limit. The best point in the trade off curve will be somewhere around 10 to 100KHz.

Don't even think about it. Use a G10 tube or other plastics

The coil will be nearly as long as it is big around. You are making a transformer with a large gap. The two gaps should be at least a few times further apart than they are wide.

You may want to place the running frequency down near the 10KHz range. This makes passing FCC a lot easier.

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D from BC 18 years ago

One way I've thought of induction charging is to think of a transformer with a detachable core section and secondary winding.

For example: Take a big ol 60Hz transformer with separate primary and secondary windings. As on:

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Slice it in half to make two C core rod inductors. Get induction charging whenever the two half's meet.

It's bulky but demonstrates the idea at low frequency...

Same idea at higher frequencies with different core material and smaller cores.

D from BC

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JosephKK 18 years ago

frans wiersma snipped-for-privacy@katogroup.eu posted to sci.electronics.design:

About 20 years ago Hughes patented a magnetic recharging paddle for electric cars. Variations and derivatives have been used for recharging electric toothbrushes for over 40 years.

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