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Wireless Transmission of Power

  1. Aug 3, 2009 #1
    Dear Physics Forums Users,


    I have a Bachelor of Science degree on Physics and Applied Mathematics, currently on the way out of a masters in EE. As a graduation project, I chose wireless power transmission as the project topic.

    I found two wireless transmission schemes that got some recent traction which claim to overcome some or all of the range related problems (enabling more than charging toothbrushes):

    1. WiTricity by Dr. Marin Soljacic (MIT)
    2. Vortex Wireless Power Transmission by Dr. Konstantin Meyl (University of Applied Sciences at Furtwangen, Germany).

    I am trying to theoretically compare systems, build and test their efficacy.

    Soljacic system uses what is termed as evanescent fields, these fields much like quantum tunneling field effect penetrate physical space and die out in a somewhat exponential fashion. My question is about Meyl System, I am unable to locate any serious treatment of scalar waves in a textbook or an academic paper other than Meyl's badly translated book Scalar Transponder .

    If you know of any credible references on Scalar Waves (refuting or supporting, it does not matter as long as they are robust), please let me know.
     
  2. jcsd
  3. Aug 4, 2009 #2

    berkeman

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    I did a Google search for "wireless power" here at the PF, to pull up all the threads that have discussed this. Please look through these threads to see if they help.

    http://www.google.com/search?hl=en&...=&as_occt=any&cr=&as_nlo=&as_nhi=&safe=images

    Note that only mainstream science is discussed here in the technical forums at the PF. I'm not sure your quote qualifies as mainstream science:

     
  4. Aug 5, 2009 #3

    es1

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    No wonder it is so hard to search for scalar field theory. They overload some common terms. "Scalar wave" seemed a bit contradictory. Now I know why.

    http://en.wikipedia.org/wiki/Scalar_field_theory_(pseudoscience)#Terminology [Broken]
     
    Last edited by a moderator: May 4, 2017
  5. Aug 6, 2009 #4
    Dear Berkeman,


    Dr. Marin Soljacic's wireless power transmission system operates on the principle that slowly-evanescent electromagnetic fields can be utilized for effective/less-loss power transmission across distances without wires.

    Here are a few references:
    A. Karalis et al. / Annals of Physics 323 (2008) 34–48
    A. Kurs et al. / Science Vol 317 (2007) 83-86

    Here is a wikipedia article on Evanescent Waves / Magnetic Fields:
    http://en.wikipedia.org/wiki/Evanescent_wave


    So in short, it's as mainstream science as apple pie.


    Cheers.


     
  6. Aug 6, 2009 #5
    Thanks Es,


    Pseudo theory classification does not look very encouraging. Unfortunately Wikipedia article does not get into detail about how scalar field theory became a "pseudo theory".

    It's best not to take anyone's word for "pseudo" or "commonly accepted" theories as not too long ago, flat earth was moved from one to the other.


    Cheers.


     
    Last edited by a moderator: May 4, 2017
  7. Aug 6, 2009 #6

    berkeman

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    Hmm. So in the context of EM, "evanescent" means near-field, it looks like. Okay.

    So are there practical applications here, or not really practical until you get to field strengths that are not good for human tissue? Technical people are not stupid. If there were practical applications that were safe, it seems like there would be things coming to market, no?
     
  8. Aug 7, 2009 #7
    Hello Berkeman,


    I should have mentioned that INTEL already bought this technology (Evanescent version, not the second one I mentioned).

    Here is their demonstration video:

    http://www.mefeedia.com/entry/wirel...nt-wireless-power-research-intel-day/19736570

    Human Tissue absorption... Their model and empirical evidence suggests it's not a problem.

    Real issue is something like this, in antenna theory it's well known that a certain portion of the electron gas passing through an antenna causes an EM reflection into near field and re-absorbed back. Through impedance matching etc. virtually all operators try to minimize that leeching part. So in a sense, a problem became a solution here (near field effect which was undesirable from communications theory point of view). Much like the concept of Cavitation, we knew certain frequency of sound can cause cavitation effect (and destroy submarine propellers for example) but it took nearly a century 'til we figure out that we can use the same effect for transferring energy to liquids (Which spawned the field of Sonochemistry).


    However my primary question remains about the second (Dr. Konstantin Meyl invention) wireless power transmission system. He is not doing a rigorous proof of his theory nor could I find anything seriously supporting/refuting what he is demonstrating... weird?


    Cheers.


     
    Last edited by a moderator: Aug 7, 2009
  9. Aug 8, 2009 #8
    It is nonsense. Don't waste your time with it.

    Absolutely nothing new in resonant coupled coils. It is 1920s technology.

    It is just near field which was what Hertz used rather than the far field which is the normal mode for radio transmission over much greater distances.

    I gather they have acheived a 45% coupling over two metres with whopping 60cm coils. The size of the aerials tend to a significant proportion of the gap you are trying to bridge. They use more wire in the coils than if they just ran a simple power wire from A to B. The overall efficiency will always be poor. You have to convert AC to DC then to RF then back to DC.. Overall you get less than 20% efficiency.

    You wont get much more than 2 metres. The efficiency will be pretty poor further apart and there is a limit to how big you can make resonant coils at a given frequency.

    The bit about energy wont be be dissipated in other surrounding wiring/objects is particularly nonsense.

    I thought it was an April Fool joke at first sight.

    Don't be surprised if it is all quietly forgotten.
     
    Last edited: Aug 8, 2009
  10. Aug 8, 2009 #9
    OP I suggest you look into tesla's work on this.
     
  11. Aug 8, 2009 #10

    negitron

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    Tesla's work on wireless power was garbage.
     
  12. Aug 8, 2009 #11
    How so?
     
  13. Aug 8, 2009 #12

    negitron

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    It was completely impractical and highly inefficient, for openers. Not to mention dangerous. Wireless power is fine for near-field, low-power applications but a practical impossibility for high-power far-field transmission.
     
  14. Aug 8, 2009 #13
    Perhaps if he had been given a decent chance he might have got somewhere.
     
  15. Aug 8, 2009 #14

    negitron

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    No. Even with today's technology we cannot create a global wireless power system such as he envisioned, even if we wanted to.
     
  16. Aug 8, 2009 #15
    ok no point arguing you win.
     
  17. Aug 8, 2009 #16

    berkeman

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    Good choice. Note, however, that there were some proposals for microwave beaming of power from orbital solar arrays back down to receiving stations on the Earth. But the cost-to-orbit was quite high, and as you can imagine, pilots weren't too keen on the idea.
     
  18. Aug 8, 2009 #17

    negitron

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    Some of these are still viable; if the bean is spread over a wide area, say, an acre or two, the power density becomes low enough that it's safe for anything passing through it even in the gigawatt range. Cost is the single largest obstacle here.
     
  19. Aug 8, 2009 #18

    berkeman

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    Interesing, I didn't know that development. Thanks.
     
  20. Aug 9, 2009 #19
    Well, from all of this, I can only say that I'm surprised that Intel is making a deal of induction coupling. Took them 100 years to catch on :uhh:

    Most any engineer who's worked with the design of induction heaters has seen the trick with the coil and a small light bulb. We also did the same trick in high school physics class.

    I used to work on trans-dermal power transfer for medical implants - the same thing.
     
  21. Aug 9, 2009 #20
    How can anybody seriously believe that Tesla could do things over 100 years ago that nobody has been able to repeat???

    Tesla is the patron saint of crackpots.
     
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