Talk:Wireless power transfer/Archive 6

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Headings/claims

I have reworded these heading changes. "Principles of wireless energy transfer" would be a misnomer as worded, part of the section shows a history similar wireless telegraphy, people coming up with systems based on a miss-understanding of the physical world, they didn't come up with any "Principles" used later on.

"Tesla's abandoned work" makes it sound like Tesla was on to something. The larger worldwide system was not based on any know principle, it came from an aether theory fantasy in Tesla's mind. It was not "abandoned" in so much as it never worked. Fountains of Bryn Mawr (talk) 18:49, 27 October 2016 (UTC)

I beg to agree on disagreement, especially, "abandoning work" is no statement about it being "on to something", imho. If "foundational efforts" would have suited better compared to "principles"? Even if I prefered the structure, which I intended to establish, I won't care until further notice. Just let me know, when I could be of some help. :)- Purgy (talk) 07:13, 28 October 2016 (UTC)
If you can see better wording please add it. I find it hard to characterize things before microwave because most sources I find on Wireless Power/history do not cover any of this, and they treat Tesla as a footnote[1][2][3], i.e. we are are working outside RS. I think we can go beyond that as a way of adding context by describing it. Fountains of Bryn Mawr (talk) 13:32, 28 October 2016 (UTC)

Edited "Tesla" section for improved readability and factual accuracy

  • Tesla's patented high frequency "System of Electric Lighting" was one wire, not wireless.
  • Tesla selected Colorado Spring as the location for the Experimental station because of the availability of electric power, not because of its elevation.
  • The C/S oscilator developed just over 1 megavolts electrical output, not 10 megavolts.

GLPeterson (talk) 04:30, 28 October 2016 (UTC)

Being fully aware of your opposed perspective, I want to explicitely make note of me not perceiving your edits as furthering improved readability, and also that I perceive them as (intentionally?) introducing biased POVs. I won't care until further notice. Purgy (talk) 07:00, 28 October 2016 (UTC)
Reason for move to Colorado Springs? We have to go with secondary sources:
  • Tesla: Inventor of the Electrical Age by W. Bernard Carlson, page 264 - "Moreover, by being in the mountains, Tesla could study how currents were conducted through both the earth’s crust and the atmosphere at high altitude."
  • Tesla, Master of Lightning by Robert Uth, page 92 - "What of Tesla's scheme to transmit electrical energy through the upper atmosphere — the very idea that brought him to the foot of Pikes Peak?"
Tesla floated the idea that he simply went to Colorado Springs for the AC power supply in his 1916 testemony[4] when pressed by his own lawyer. Primary source so not usable as such and we have to take into account the purpose of this testimony; Tesla was trying to make a claim on inventing radio and down-playing the fact that he had built a conduction based system, not a radio system.
"one wire, not wireless" could be refined and wording could be changed to "in the megavolts range" unless nailed down to a better source (just haven't looked). Fountains of Bryn Mawr (talk) 14:57, 28 October 2016 (UTC)

Protected edit request on 2 November 2016

Early on he seemed to borrow from the idea's of Mahlon Loomis,

Should read 

Early on he seemed to borrow from the ideas of Mahlon Loomis,

Schemathings (talk) 16:52, 2 November 2016 (UTC)

Done — Martin (MSGJ · talk) 09:25, 3 November 2016 (UTC)

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Non- vs. Radiative and Near- vs. Far-Field

I have no idea about the specific terms of this topic, but to my abstract knowledge near- and far-field are mathematical constructs, describing the dominant part of the EM-wave in the respective region of the emitter (having of course also other, most relevant differences, like energy coupling). The "measure" for "near" and "far" is thereby given by the ratio of the wavelength of the EM-wave and the distance. So for each setting there is a specific distance, where the contributions of near- and far field to the EM-wave are of equal magnitude. This distance might be considered as a natural boundary between those regions.

In any case, both "fields", near- and far-, are inherently bound to radiation, and so -not knowing about the local habits- talking about the use of "near field effects" as "non-radiative" takes me by surprise. Even when the exploited effects are physically confined to the "near neighbourhood", they are inherently based on "radiation".

I do not dare to touch the tangled mass of notions like capacitive, inductive, magnet/o-dynam/ic, (electro/magneto)-"static", especially in connection with "resonant", but I think there are still many skeletons in the closet, all in need of some contemporary EM-refreshing. -Purgy (talk) 07:33, 30 November 2016 (UTC)

Read the Field regions section. It's all laid out there. Everything in the section is supported by modern mainstream wireless power texts; check the copious sources cited. For example, on near-fields being "nonradiative" and far-fields being "radiative", see Agbinya, p.1. Cheers --ChetvornoTALK 11:32, 30 November 2016 (UTC)
The part of your statement above I disagree with is: "...both "fields", near- and far-, are inherently bound to radiation... Even when the exploited effects are physically confined to the "near neighbourhood", they are inherently based on "radiation"". Radiation means electromagnetic waves (radio waves). The characteristic of radiation is that it leaves the transmitter whether or not a receiver is present to receive it, while the energy in near fields stays with the transmitter unless there is a receiving coil nearby to absorb it. Power can be transmitted by near fields without any being radiated. For example, consider two coils of wire near each other, one powered by current from the 60 Hz wall plug, the other connected to a light bulb which is lit. There is no "radiation" going on here; the power is crossing the space from the transmitting to the receiving coil through the (near field) magnetic field, by inductive coupling (electromagnetic induction), as in a transformer. If you separate the two coils, the light goes out and then no power is drawn from the source by the transmitting coil, indicating that no power is being radiated as radio waves. --ChetvornoTALK 12:53, 30 November 2016 (UTC)
May I point you to the first part of my very first sentence? :) Our notions on "radiation" do not conform. Your "radiation" is my "far-field approximation" of radiation. personally, I prefer to call EM-effects per "radiation", when their propagation does not macroscopically involve some medium. So in my nomenclature, if some device is charged via a cable it is not radiative, however when it is charged, read out, modified, ... across some distance, to me radiation is involved. To be more precise, radiation happens to me whenever there is some non-zero d/dt, so along a high voltage 60Hz transmission line you have heavy radiation losses, and in a near-field communication environment you do not only have power supply, but also information interchange across the EM-fields.
I admit that considering a transformer a radiative device is somehow bewildering, but I think, in this article the term near-field interaction to be far more physically appropriate than the -to my measures- factually wrong term non-radiative, which stems imho from aged mind maps of Maxwell's equations.
I certainly do not want to change the habits and the common lingo, but I felt urged to mention the theoretical background. The view of inductive coupling is just an approximation of the radiative process, unified in the relativistic field tensor, where motors, transformers, inductive and capacitive coupling, ... are all the same. -Purgy (talk) 10:12, 1 December 2016 (UTC)
I see your point, you are saying that any transfer of power across space by time-varying electromagnetic fields could be called "radiative". But you are using the term "radiative" in a way different from its use in the wireless power field, and indeed in all electromagnetics. In electromagnetics the term "radiation" is reserved for the far-field components, which travel as electromagnetic radiation, and the transfer of power by near fields is called "induction" (electrostatic induction, electromagnetic induction). It is important for WP articles to use the correct terminology for their field. The terms "radiative" and "nonradiative" are used as categories of wireless power systems in most textbooks on the subject [5], [6], [7], [8], [9] so my feeling is they need to be in the article. --ChetvornoTALK 00:43, 2 December 2016 (UTC)
I strongly disagree with your claim "In electromagnetics the term "radiation" is reserved for the far-field components". It may well be so in the wireless power field, and I certainly won't move a single finger to change any habits in this important, highly practical field, and also not to change any wordings in Wikipedia articles on these topics. However, I sensed the need to point to the rather arbitrary discrimination between near- and far-field, governing the quite obvious term "radiation" to be unnecessarily vague. How do you think about a wave guide, transmitting microwave power across a single conductor? You cannot identify near and far field in this setting, and it is "non-conductive" either, because this all is derived for some simple, highly theoretic boundary conditions, allowing for this well known separation in "components", which have no physical significance beyond their decay rate in exactly these boundary conditions (vertical lambda/2-dipole above a halfplane). The advances in wireless power are to be expected in finding similarly interesting boundary conditions as the waveguide with circular cross section offers.
Please, remember also what I called these terms: tangled mass of notions like capacitive, inductive, magnet/o-dynam/ic, (electro/magneto)-"static", especially in connection with "resonant". These are all remnants of early understanding of EM, focused on parts of the whole theory.
Why use "non-radiative", if "near-field" is available, more correct and even more precise, at all? Need of "soothing" caused by excluding "radiation"? Holy marketing! ;) -Purgy (talk) 08:58, 2 December 2016 (UTC)

Archives not listed

The archives of this Talk page are not listed at the top for some reason by the archiving bot. Does anyone know how to make it do that? I don't know enough about archiving to find what's wrong. Thanks. --ChetvornoTALK 01:47, 6 May 2017 (UTC)

Fixed. It was a complicated (and interesting to me!) situation...feel free to ignore the following technical analysis if you don't care:) Many years ago, the page was at Wireless energy transfer, whose talkpage was archived normally at Talk:Wireless energy transfer/Archive 1 and then continuing as /Archive 2. The page was then renamed (in several steps) eventually landing here at Wireless power transfer. The editors who moved the page moved the talkpage itself but didn't move the talkpage archives, so they were stranded at their old name. The archive bot then continued to archive normally, continuing to fill /Archive 2 and subsequent as subpages of the new name, leaving Talk:Wireless power transfer/Archive 1 vacant. The talk-header with archive search noticed that there was no /Archive 1 of the current name, so it didn't think there were any archives. I inserted the old-name's talk archives and now we're all set. DMacks (talk) 05:06, 6 May 2017 (UTC)
Thanks so much! It looked to me like the bot was working ok, but that problem you found would never have occurred to me. I'll have to remember it in case I run across it again. Thanks again. --ChetvornoTALK 07:39, 6 May 2017 (UTC)

Good Mention of Inventor Nikola Tesla Wireless Power Experiments

glad a mention of nikola teslas experiments to transmit wireless eleltric power. July 4th 2017 will be the 100th anniversary of the destruction of the 300 foot wodend power tower by the order of the us overment suppossely because erman spies could have used to thoer to spy on us shippin off long island .america was at war in world war 1 at the time. july 4th 1917.hoefully the world will not have to wait another 100years for wireless power to be in use. also, no mention in article aout ELETRIC ROADS in south korea and now sweden usein wireless power transfer to power and rechare a ev electric vechicle thanks.Edson andre' johnson d.d.ulc,amm — Preceding unsigned comment added by TheStilletoKid (talk • contribs) 03:48, 18 June 2017 (UTC)

Recent edits on "2nd resonance" systems

I am concerned about the text and image Discharger1016 recently added to the Resonant inductive coupling section:

Only the resonance on the secondary side is effective.　This is called 2nd-resonance technology.
"Power transfer is performed only by the resonance of the secondary side. This is called phase synchronization."

This confusing text seems to imply that in resonant inductive power systems resonant circuits are not necessary in both the transmitter (primary) and receiver (secondary) circuits as the rest of the article indicates, but would work just as well with a resonant circuit only in the receiver. The cited sources do not support this. They show that such "single-tuned" power systems work and are used in cases such as railway power systems where the transmitting coil cannot be a tuned circuit. This should be mentioned in the article. But there is no indication that they are as efficient as double-tuned systems:

  • [10] - Powerpoint presentation may describe such a single-tuned inductive power system for a railway (its hard to tell because the circuit is not given) but it does not compare single-tuned and double-tuned systems or say single-tuned is as efficient.
  • [11] - entirely in japanese and does not render in my browser
  • [12] - Apparently an abstract of a japanese article behind a paywall. Can't tell whether it's an article from a reliable technical magazine or a promotional article from a commercial site.
  • [13] - An abstract of a paper presented at a conference. It says "...it is possible to achieve highly efficient wireless power transfer with a resonant structure in only the secondary side." However, there is no indication it compares single-tuned and double-tuned power systems or that a single-tuned system can be as efficient as double-tuned.
  • [14] - Just an advertisement for a japanese electronics magazine, without access. If there is an article in this magazine which supports the editor's position, he doesn't indicate which one.
  • [15] - A brief single page japanese description of railway inductive power system. No circuit or technical specs.

Unless adequate sources supporting it are found, I think this addition should be reverted. --ChetvornoTALK 09:58, 16 May 2017 (UTC)

Let's review the history of wireless power transfer again. The world's first practical use was in 1993. This is the achievement of John Boys. Please refer to the website of the Japanese company. A Brief History of Development
The Tutorial of John Boys can be understood that if you read it carefully, he is analyzing the coupling of resonance on the secondary side . In particular, you should refer to P13, P14, P89 etc.
Next, why he does not adopt dual resonance is in P29 and P30, this is because the phase characteristic Zp becomes complicated at heavy loads.
And there are many references from P94 to P96. Originally we should read all of them, but the easier way is to find out about patents of Japanese companies that partnered with John Boys. There is no concept of dual resonance in the patent applications of them and their competitors from 1990 to 2000 when they were invented. Those are resonance of the secondary side only.
What I'd like to say is that it should be responsible for the comparison of single and dual resonances by WiTricity who appears later and presented dual resonance.
WiTricity has not fulfilled its responsibility. However, one of other Japanese company is comparing single resonance and dual resonance. These data are on a verifiable website. Anyone can download it for free. I show you extractions those explanations.Extractions,Catalog download (red bar)
According to 【Exhibition Report】 Techno Frontier 2017 - New Energy Newspaper, it is :written as follows.
- Summary -
The "2nd-resonance" technology, which was demonstrated at the booth of OMRON, maintained about 90% without drop in efficiency, even if the axis of the coil was shifted by 10 cm.
The point is to construct the resonance circuit only on the secondary side. If constructed on both the primary side and the secondary side, transfer distance become long, but if axis of the coil shifts, the efficiency drops extremely.
Next, There is also an interesting description in A Brief History of Development. It is said that these descriptions are quoted from DAIFUKU NEWS No. 161 (August 2001), and this DAIFUKU NEWS No. 161 seems to be a pretty well-known report. And when search it on the net, it is being referenced many times. But I have not read it yet.
Referenced documents are as follows.
That is, SCMaglev's wireless power transfer technology of Japan Railway Technical Research Institute is referring to this (DAIFUKU/John Boys) technology. And Not only is it being referred to, but also presence of contact between key persons are written.
I present it for reference.
In any case, these patent applications are considered to be evidence that John Boys realized practical using of wireless power transfer technology before MIT.
I never meant to dismiss the achievement of Marin Soljačić. However, I would like everyone to understand that the true pioneer of the wireless power transfer is John Boys.--Discharger1016 (talk) 19:51, 18 June 2017 (UTC)

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Coupling in WPT

Apologies for being sloppy. First, with the deleted sentence I intended to address situations like e.g., radio or TV broadcasting, where the coupling, in the usual sense of mutual interaction, of receiver(s) and transmitter via the EM- field is absolutely negligible (non-reciprocity?). The transmitter is in no way appreciably concerned when some receivers' antennae within its transmission range are removed or added. In reasonable WPT however, afaik, adding a receiver or switching off one will result in a change in load of the transmitter, so that they may be considered as noticeably coupled. Second, I did not intend to deny broadcasting of power. Regards, Purgy (talk) 18:50, 17 May 2018 (UTC)

Okay, I see what you mean, you have a point. However I really don't think this minor technical point belongs in the introduction. Many (most) of the readers coming to the introduction will be general readers with no technical knowledge. They need to understand the more fundamental point that wireless communication and wireless power are alike, they use the same underlying technologies. My feeling is the appropriate place for the sentence would be in the 3rd paragraph of the "Overview" section, where this is explained. --ChetvornoTALK 19:16, 17 May 2018 (UTC)
Please, allow for my disagreement. Imho, it is the most important task in WPT to find scenarios (resonance?) of wireless, but "most strong" coupling, to overcome the effects of near/far-field, which are well established only for extreme cases, the transformer and the dipole field over a half plane. I think it is worth to mention that the former is broadly used in WPT (this is done already), but the latter is useless, and that the main task is to search for settings (signal forms and boundary conditions?) which allow for a coupling like with the transformer, but avoids certain inconveniences or disadvantages like with the capacitive analogs. Certainly, anything wireless rests on the propagation of EM waves without medium, but a strong energy/power coupling across this propagation is a formative property for WPT, and not a minor technical point.
I won't interfere about this in the article. Purgy (talk) 06:34, 18 May 2018 (UTC)
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