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I think I'm going to move the article ["Resonant energy transfer"] to resonant inductive coupling or resonant transformer. It seems to be a better name; there's other resonant energy transfers that are not inductive.- Wolfkeeper 23:57, 12 November 2009 (UTC)
Could someone please change the source for reference 6. The maximum link efficiency had already been derived at least 4 years earlier in 'K. Van Schuylenbergh, R. Puers, "Inductive Powering - Basic Theory and Application to Biomedical Systems", 2009' and there is no reason why WiTricity's white paper should be the source. — Preceding unsigned comment added by 137.222.185.147 ( talk) 11:42, 28 January 2015 (UTC)
The sub-heading 'Coupling Coefficient' needs re-writing. Simply look to the first sentence to see why:
"Well misunderstood, the coupling coefficient is often said to be the ratio of flux interlinking to the secondary coil, but it is a misunderstanding."
There's no reason at all to suggest a misunderstanding in an informative article, never-mind book-ending it like that.
The section is also unclear at points: "The coupling coefficient is fixed by the positional relationship between the coil and the coil."
and uses a lot of unexplained technical language: "the coupling coefficient does not change between when the system is in the resonance state and when it is not in the resonance state, but the ratio between the mutual flux and the leakage flux changes greatly."
There are also no citations anywhere in the section.
I would edit this myself, but I do not have sufficient experience to be able to explain these terms.
209.6.37.209 ( talk) 15:55, 28 December 2016 (UTC)
I have removed this from the article "but the ratio between the mutual flux and the leakage flux changes significantly. Specifically, mutual flux increases significantly when the system is in a resonant state." Why do we need to say this? The transformer coupling coefficient is defined purely in relation to the transformer, not the resonant circuits. It is defined under open circuit conditions (so there can be no question of resonance) and under open circuit conditions the ratio of leakage and mutual flux does stay constant with applied voltage. It can only get to be different if a load is applied. True, that load can be a resonating capacitor, but stating this in the section about the transformer is very misleading. Spinning Spark 16:38, 9 January 2017 (UTC)
The parallel capacitor Cs on the primary side has no meaning. It should be removed. Only the resonance capacitor of the secondary side has meaning.-- 121.2.184.184 ( talk) 17:37, 9 January 2017 (UTC)
It would be nice to explain why there are coils that are not connected to the load, and in the diagram of the Soljačić system, not connected to the oscillator? Are these somehow massaging the magnetic field so it acts more strongly on the coils that are connected, or is this an error in diagramming? -- Beland ( talk) 15:30, 11 January 2018 (UTC)
In this page the resonance mechanism is suggested to improve the coupling factor whereas it is only a way to reduce losses on both the generator side and the load side for the same field level as it is also explained somewhere in the page. Resonance is a first consequence of the impedance matching process, it is similar for all types of couplings ( mechanical, acoustic, magnetic, electric) and consists in compensating a reactive link impedance by a conjugate reactance, see for instance: /info/en/?search=Impedance_matching and in particular the 'Maximum power transfer matching' subsection. All this is well known for centuries and well described in many old books, see for instance VACUUM TUBE AMPLIFIERS Copyright, 1948, by the McGraw-Hill Book Company, Inc, chapter5 pp201 to 226, for a direct reading see https://www.jlab.org/ir/MITSeries/V18.PDF. This book summarized works done well before (before 1937 at least). The link is not affected by the resonance effect that is an internal process in the devices, the coupling factor 'k' is a constant that doesn't depend on frequency but only on distribution of charge and currents (then electrodes and coils geometry). The appropriate quantity to take into account the "resonance" effect is the coupling index 'kQ' introduced in the bottom of page 202 in the book. It is also introduced in this page under a new name "factor of merit" that if not inappropriate but somehow hides the historical succession of events. Chapter 5, also address the asymmetry between coils Q-factors 'Q1, Q2' (the second resonance awkward idea). The two introduction figures are then dogmatic according to me as they indicate a sort of focalization of field lines whereas, as explained, resonance does not affect coupling 'k' and field line distribution or it should be proved with actual data. The chapter "Witricity resonant...." where the coupling index is introduced is totally commercial. The commercial name "Witricity" should not figure here as the information introduced apply for all resonant systems. By the way, according to me the only specific aspect of the Witricity patent is the use of two core-less transformers on both side to provide resistance tuning. The whole tuning process is two fold reactance and resistance tuning as explained in the following didactic videos I made a few years ago when teaching the field in University: https://www.youtube.com/watch?v=yKmseA3Fd-g for inductive coupling and https://www.youtube.com/watch?v=YegIW-1hbvQ for capacitive coupling. Finally the dipole field admittedly decreases as 1/r3, evanescent waves and field (exponential decrease) are only obtained at the interfaces between two mediums. Considering that a magnetic transformer is based on evanescent wave whereas it can be described accurately by non propagating field (quasi-static approximation) is totally inappropriate, dogmatic and doesn't fit with the Okkam razor principle. According to me, this page was well written up to January 2017, then it was turned into some form of advertising for a given company and became more and more dogmatic with time (the awkward figures introduction used to defend a dogmatic content), the use of evanescent field suggesting that the idea is new. Besides the duality theorem that states that a dual capacitive coupling implementation exist (at least theoretically) is totally avoided in the page and I think creating a specific resonant capacitive page would not be an example of good practice. I am afraid that a personal direct contribution on the page will be perceived as non neutral, I am involved in many articles, patents concerning non-radiating near-fields and longitudinal capacitive coupling (resonant of course). Henri BONDAR ( talk) 06:39, 10 January 2019 (UTC)
I suggest tagging this article for non neutral point of view (WP:NPOV policy). As said I don't think adding a Resonant capacitive coupling page is a good idea. As an expert in non-radiating near-field applications, I suggest to separate clearly the coupling aspects as well described in the /info/en/?search=Coupling_coefficient_of_resonators page, from resonance considerations that are specific implementations in the loads and generators devices and not specific to Witricity patent as falsely suggested here. They can be introduced straightforwardly using impedance matching considerations (see: /info/en/?search=Impedance_matching#Maximum_power_transfer_matching) and the coupling index kQ as introduced at least since 1937 in MacGraw-Hill book reference. Henri BONDAR ( talk) 13:33, 12 January 2019 (UTC)
I agree with a number of points made here. Note that I have recently entered the wireless power transfer space, which is what brought this article to my attention, and Witricity is a competitor with the company I work for. Even still, repeated references to Witricity (or any particular wireless power transfer company which is not historically significant in general consensus) seems commercial and very out of place. Use of the terminology "evanescent" has commercial benefit for Witricity, and in the past they have used that terminology (which is non-standard) to add credibility to e.g. their patents. Impartial background investigation is warranted, though I don't have any references on hand. This isn't to accuse Witricity of editing the page themselves, but it's obvious that their work was a major influence on the article, and unnecessarily so. It is not an impartial article, and the content does not belong in an encyclopedic reference. There was also a noted shift in content quality and impartiality in the closely related article on evanescent waves, where the definition of evanescent has become increasingly ambiguous since about 2015.
The discussion by Henri above certainly is sound, but if I had to disagree with any point, it would be the quibble with the field lines. Resonance does change the field intensity near a receive coil, but only in the same way that input impedance matching increases the field intensity at the transmitter - the power transfer from generator to transmit coil is necessarily larger so of course the field is stronger. But observe that when a receive coil in a resonant circuit is placed into the field, the only way for the received signal strength to increase, is for the magnetic field intensity to increase inside the loop. Put another way, reactive energy stored in the resonant circuit has a significant impact on the local H field around the receive coil, via increased loop current. The power transfer to the receive circuit from the receiving coil is also dependent on impedance matching, but this is a distinct effect.
It's hard to separate the receive circuit from the transmit coil circuit. Above, I mean that the magnetic field at some position in space is hardly changed when a receive coil is introduced, whether the loop is shorted or open, but if you put a resonant capacitor in series with the receive coil (with a closed loop), the magnetic field strength inside the loop is dramatically increased relative to the transmit coils field contribution. The contribution to the field from the transmit coil is not changed, but the reactive energy stored in the resonant network contributes significantly as well.
Comments from others are encouraged. Sjgallagher2 ( talk) 19:23, 22 October 2021 (UTC)
Normally coupled oscillators create amplitude modulation if they are in in resonance. Should that be explained to? Quaderratistteuer ( talk) 19:40, 30 September 2020 (UTC)
This is the
talk page for discussing improvements to the
Resonant inductive coupling article. This is not a forum for general discussion of the article's subject. |
Article policies
|
Find sources: Google ( books · news · scholar · free images · WP refs) · FENS · JSTOR · TWL |
![]() | This article is rated C-class on Wikipedia's
content assessment scale. It is of interest to the following WikiProjects: | |||||||||||||||||||||||||||
|
I think I'm going to move the article ["Resonant energy transfer"] to resonant inductive coupling or resonant transformer. It seems to be a better name; there's other resonant energy transfers that are not inductive.- Wolfkeeper 23:57, 12 November 2009 (UTC)
Could someone please change the source for reference 6. The maximum link efficiency had already been derived at least 4 years earlier in 'K. Van Schuylenbergh, R. Puers, "Inductive Powering - Basic Theory and Application to Biomedical Systems", 2009' and there is no reason why WiTricity's white paper should be the source. — Preceding unsigned comment added by 137.222.185.147 ( talk) 11:42, 28 January 2015 (UTC)
The sub-heading 'Coupling Coefficient' needs re-writing. Simply look to the first sentence to see why:
"Well misunderstood, the coupling coefficient is often said to be the ratio of flux interlinking to the secondary coil, but it is a misunderstanding."
There's no reason at all to suggest a misunderstanding in an informative article, never-mind book-ending it like that.
The section is also unclear at points: "The coupling coefficient is fixed by the positional relationship between the coil and the coil."
and uses a lot of unexplained technical language: "the coupling coefficient does not change between when the system is in the resonance state and when it is not in the resonance state, but the ratio between the mutual flux and the leakage flux changes greatly."
There are also no citations anywhere in the section.
I would edit this myself, but I do not have sufficient experience to be able to explain these terms.
209.6.37.209 ( talk) 15:55, 28 December 2016 (UTC)
I have removed this from the article "but the ratio between the mutual flux and the leakage flux changes significantly. Specifically, mutual flux increases significantly when the system is in a resonant state." Why do we need to say this? The transformer coupling coefficient is defined purely in relation to the transformer, not the resonant circuits. It is defined under open circuit conditions (so there can be no question of resonance) and under open circuit conditions the ratio of leakage and mutual flux does stay constant with applied voltage. It can only get to be different if a load is applied. True, that load can be a resonating capacitor, but stating this in the section about the transformer is very misleading. Spinning Spark 16:38, 9 January 2017 (UTC)
The parallel capacitor Cs on the primary side has no meaning. It should be removed. Only the resonance capacitor of the secondary side has meaning.-- 121.2.184.184 ( talk) 17:37, 9 January 2017 (UTC)
It would be nice to explain why there are coils that are not connected to the load, and in the diagram of the Soljačić system, not connected to the oscillator? Are these somehow massaging the magnetic field so it acts more strongly on the coils that are connected, or is this an error in diagramming? -- Beland ( talk) 15:30, 11 January 2018 (UTC)
In this page the resonance mechanism is suggested to improve the coupling factor whereas it is only a way to reduce losses on both the generator side and the load side for the same field level as it is also explained somewhere in the page. Resonance is a first consequence of the impedance matching process, it is similar for all types of couplings ( mechanical, acoustic, magnetic, electric) and consists in compensating a reactive link impedance by a conjugate reactance, see for instance: /info/en/?search=Impedance_matching and in particular the 'Maximum power transfer matching' subsection. All this is well known for centuries and well described in many old books, see for instance VACUUM TUBE AMPLIFIERS Copyright, 1948, by the McGraw-Hill Book Company, Inc, chapter5 pp201 to 226, for a direct reading see https://www.jlab.org/ir/MITSeries/V18.PDF. This book summarized works done well before (before 1937 at least). The link is not affected by the resonance effect that is an internal process in the devices, the coupling factor 'k' is a constant that doesn't depend on frequency but only on distribution of charge and currents (then electrodes and coils geometry). The appropriate quantity to take into account the "resonance" effect is the coupling index 'kQ' introduced in the bottom of page 202 in the book. It is also introduced in this page under a new name "factor of merit" that if not inappropriate but somehow hides the historical succession of events. Chapter 5, also address the asymmetry between coils Q-factors 'Q1, Q2' (the second resonance awkward idea). The two introduction figures are then dogmatic according to me as they indicate a sort of focalization of field lines whereas, as explained, resonance does not affect coupling 'k' and field line distribution or it should be proved with actual data. The chapter "Witricity resonant...." where the coupling index is introduced is totally commercial. The commercial name "Witricity" should not figure here as the information introduced apply for all resonant systems. By the way, according to me the only specific aspect of the Witricity patent is the use of two core-less transformers on both side to provide resistance tuning. The whole tuning process is two fold reactance and resistance tuning as explained in the following didactic videos I made a few years ago when teaching the field in University: https://www.youtube.com/watch?v=yKmseA3Fd-g for inductive coupling and https://www.youtube.com/watch?v=YegIW-1hbvQ for capacitive coupling. Finally the dipole field admittedly decreases as 1/r3, evanescent waves and field (exponential decrease) are only obtained at the interfaces between two mediums. Considering that a magnetic transformer is based on evanescent wave whereas it can be described accurately by non propagating field (quasi-static approximation) is totally inappropriate, dogmatic and doesn't fit with the Okkam razor principle. According to me, this page was well written up to January 2017, then it was turned into some form of advertising for a given company and became more and more dogmatic with time (the awkward figures introduction used to defend a dogmatic content), the use of evanescent field suggesting that the idea is new. Besides the duality theorem that states that a dual capacitive coupling implementation exist (at least theoretically) is totally avoided in the page and I think creating a specific resonant capacitive page would not be an example of good practice. I am afraid that a personal direct contribution on the page will be perceived as non neutral, I am involved in many articles, patents concerning non-radiating near-fields and longitudinal capacitive coupling (resonant of course). Henri BONDAR ( talk) 06:39, 10 January 2019 (UTC)
I suggest tagging this article for non neutral point of view (WP:NPOV policy). As said I don't think adding a Resonant capacitive coupling page is a good idea. As an expert in non-radiating near-field applications, I suggest to separate clearly the coupling aspects as well described in the /info/en/?search=Coupling_coefficient_of_resonators page, from resonance considerations that are specific implementations in the loads and generators devices and not specific to Witricity patent as falsely suggested here. They can be introduced straightforwardly using impedance matching considerations (see: /info/en/?search=Impedance_matching#Maximum_power_transfer_matching) and the coupling index kQ as introduced at least since 1937 in MacGraw-Hill book reference. Henri BONDAR ( talk) 13:33, 12 January 2019 (UTC)
I agree with a number of points made here. Note that I have recently entered the wireless power transfer space, which is what brought this article to my attention, and Witricity is a competitor with the company I work for. Even still, repeated references to Witricity (or any particular wireless power transfer company which is not historically significant in general consensus) seems commercial and very out of place. Use of the terminology "evanescent" has commercial benefit for Witricity, and in the past they have used that terminology (which is non-standard) to add credibility to e.g. their patents. Impartial background investigation is warranted, though I don't have any references on hand. This isn't to accuse Witricity of editing the page themselves, but it's obvious that their work was a major influence on the article, and unnecessarily so. It is not an impartial article, and the content does not belong in an encyclopedic reference. There was also a noted shift in content quality and impartiality in the closely related article on evanescent waves, where the definition of evanescent has become increasingly ambiguous since about 2015.
The discussion by Henri above certainly is sound, but if I had to disagree with any point, it would be the quibble with the field lines. Resonance does change the field intensity near a receive coil, but only in the same way that input impedance matching increases the field intensity at the transmitter - the power transfer from generator to transmit coil is necessarily larger so of course the field is stronger. But observe that when a receive coil in a resonant circuit is placed into the field, the only way for the received signal strength to increase, is for the magnetic field intensity to increase inside the loop. Put another way, reactive energy stored in the resonant circuit has a significant impact on the local H field around the receive coil, via increased loop current. The power transfer to the receive circuit from the receiving coil is also dependent on impedance matching, but this is a distinct effect.
It's hard to separate the receive circuit from the transmit coil circuit. Above, I mean that the magnetic field at some position in space is hardly changed when a receive coil is introduced, whether the loop is shorted or open, but if you put a resonant capacitor in series with the receive coil (with a closed loop), the magnetic field strength inside the loop is dramatically increased relative to the transmit coils field contribution. The contribution to the field from the transmit coil is not changed, but the reactive energy stored in the resonant network contributes significantly as well.
Comments from others are encouraged. Sjgallagher2 ( talk) 19:23, 22 October 2021 (UTC)
Normally coupled oscillators create amplitude modulation if they are in in resonance. Should that be explained to? Quaderratistteuer ( talk) 19:40, 30 September 2020 (UTC)