Induction coil charging question(s)

Question

Induction coil charging question(s)

salukikev (Mechanical)

(OP)

9 Nov 15 05:02

Hi,
I'm a ME currently dabbling in EE tasks for this prototype. I actually just purchased this handy coil kit, and I'm eager to play around with it. Naturally the coils aren't coincidentally the exact dimensions I need, but they're not too far off so I have a few questions (& this is only for a proof of concept, not production):

1. In this kit/configuration the coils are intended to be concentric (like all configurations I presume) such that you would lay your item to be charged/powered on top. Like when you'd lay your phone on a charging pad. In my item, I have the opportunity to position the coils not only concentric, but also planar if I vary the coil diameters. Would that configuration be any better or worse? To clarify, I'm talking about stacking one coil inside the other, not just on top of it.

2. Regarding dimension adjustments, can I customize the coil diameter? I'd like to rewrap the wire to about 2x the current diameter. Can I do that using the exact same length/wire just less coils? Would it be better to use a different wire diameter? I'm not sure how to calculate this.

Thanks for any help!
-k
*PS. I think I posted this to the wrong forum, so re-posting here

MacGyverS2000 (Electrical) · Answer 1 · 2015-11-09 11:24:11

Look up the equation for determining a coil's inductance... I think you'll quickly see how changing the diameter of the coil affects the coils value.

Dan - Owner
http://www.Hi-TecDesigns.com

salukikev (Mechanical) · Answer 2 · 2015-11-09 16:36:40

Well that doesn't really answer my question. I found the calculation (& calculator listed here) But I was asking about different coil sizes and how that might effect the overall dynamic.

For example if I have planar coils and I match their resistance, is that any better or worse than non planar coils of the identical specification?

At the calculator above, an outer coil of 2" diameter, 12 turns delivers .189 microhenries of inductance.
a calculated inner coil of 1.625" diameter with 14.75 turns also delivers .189 microhenries of inductance. I can now arrange these coils on the same plane as the one is a smaller diameter. Another variable I could adjust is the wire diameter if the coils should be the same # of turns or length. I just don't know how this would effect their performance.

In other words, my first question has more to do with the physical arrangement than the any one specification.

Regarding my 2nd question, that may be more relevant- I want to know if I'll have to modify the circuitry if I change dimensions of the coil(s). Are you saying that if I maintain the overall inductance of each coil, while adjusting the diameter, then all else can remain as is? I would make adjustments to either # of turns or wire diameter (or maybe material?) such that I end up with an identical inductance value?

Thanks for any clarification.

IRstuff (Aerospace) · Answer 3 · 2015-11-09 18:10:51

The main user forums are intended for work-related questions, with the assumption that the poster has at least a minimum of understanding of the basic physics; there is a separate hobby forum for questions like this.

I suggest you read up on inductors, particularly on the concept of amp-turns, which will answer many of your questions. Additionally, you should investigate what the magnetic field lines of an inductor coil look like, which should immediately answer some of your other questions.

TTFN
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Induction coil charging question(s)