Wireless power transfer via inductive coupling

Note:
Schematics and information about the circuit is now available at 4hv.org:

http://4hv.org/e107_plugins/forum/forum_viewtopic.php?74096

This is a small scale demonstration of wireless power transfer between two coupled parallel LC tuned circuits, each consisting of a copper conductor loop acting as an inductor and a capacitor. Both LC circuits are tuned to equal individual resonant frequencies. One of them is a part of a 1.5Mhz radio frequency oscillator powered by 12 volts DC, while another is loaded by a 24V 5W incandescent light bulb. Brought in proximity, copper loops share a small mutual inductance, essentially forming a transformer. In order to transmit significant amount of power through this transformer a very large amount of reactive power needs to circulate in it's primary, requiring use of a thick copper tube for the conductor, and a bank of eight 6.8nF capacitors in parallel.
Receiver coil's leakage inductance is in turn canceled out by another capacitor, allowing for the maximum power transfer to the load.

Experimenting with copper loop orientations, one can find positions of the receiver close to transmitter where no power is received, as total magnetic flux crossing through the receiver loop is zero. Hence this is a directional method of power transmission.

Due to small size of the apparatus very little power is actually radiated in far field, with losses being mainly ohmic heating. Hence this method is also sometimes known as non-radiative or near-field power transmission.

Category:

Science & Technology

Tags:

• wireless power
• wireless energy
• inductive coupling
• parallel resonance
• LC circuit
• Royer oscillator
• nearfield
• near field
• evanescent wave coupling

[ebike1961]

Could a system like this be used to charge a 48v electric bicycle in an outdoor covered charging station? The current plug-in charger operates at 3w

[MarkoBakula]

@ebike1961

Hello,

I'm pretty sure it could with a little modification, if the distance is not too extreme.

[Invictus227]

What is the Black box you are using? I'm trying to figure out where I would find one and what they cost.

[MarkoBakula]

@Invictus227

It's a power supply I made. It has a toroidal transformer giving around 12V with a rectifier and filter cap - nothing special really.

[rahulras]

What happens at 0:43 .

Is there where the flux passing is 0?

[MarkoBakula]

@rahulras

That's right - with the loop plane being parallel to field lines there's no net flux passing through it. Hence the result is the same as if it was very far away.

Marko

[tongchi89]

hi good day! can i ask for the circuit design and schematic diagram.. it was awesome with your design.. can you send it to my email add... gta_jag69@yahoo.com

[jonahdavepoypoyp]

im thinking what is the schematic diagram of the receiver? what is the purpose of it???

[belgiumboy3]

my PC mouse works with this technology, my maximum range is 5 centimeters.

this technology would be helpfull for recharging batterys of pacemakers.

[burchified]

But where does the meter go?!

[HiJackZX1]

This is very cool. I am trying to add electroluminesant lighting to my car rims. The current method (pancake slip assembly) will wear out very easily. Do you think this will work to transfer from car to wheel? They would be in very close proximity. Would I have to worry about rain and elements?

[fafigueroa1]

amazing :D

[ebike1961]

@MarkoBakula

We could design the bike rack so that the headtube mounted receiver on the bike contacted the unit providing the charge. We would rather not have to include a plug. Rather just two contacting pads.

[subbero1]

If everyone would be using such stuff, the HF spectrum would be more and more polluted. This is already the case, made by cheap electronics.