Talk:Gyrator–capacitor model

Isn't this the better approach to modelling magnetic circuits?

It would be great to give some context as to how the other method of modelling magnetic circuits came into such wide usage, when the units of 1/H for reluctance have nothing to do with being a resistive (dissipative) circuit element. It seems to me (who is just starting out in trying to understand this area) that the gyrator-capacitor model makes so much more sense. Is there a benefit to doing it the other way that drove that method into such common usage and that is keeping the world (and the magnetic circuits article) from switching to this method? If so, let's say it here and say when one would chose one method over the other. Thanks. JDHeinzmann (talk) 17:42, 16 May 2015 (UTC)

I guess it is because Ohm's law is by far the most well known phenomenon in electrical science. The main purpose of an analogy is often to describe unfamiliar phenomena in terms of an already understood phenomenon. The cited paper says the traditional analogy "from the viewpoint of electronics, it is natural..." SpinningSpark 08:56, 17 May 2015 (UTC)

Yes, the gyrator-capacitor (aka capacitance-permeance) approach is far superior for dynamic systems and their losses, but not for static or quasi-static systems. At a human size scale, electrostatic forces are insignificant compared to the magneto-static forces that turn the wheels of industry. So we are much more interested in a magnetic flux than in an electrostatic field. It was therefore natural for the early experimenters to put a permanent magnet and a battery side-by-side on a table, and apply the battery’s equations to the magnet, and find that they work, resulting in the resistance-reluctance model. Yet, in some ways, the result was deeply unsatisfying; there is a “magnetic circuit”, but it is an odd circuit that has flux, but no flow. As GW Carter lamented in his book "The Electromagnetic Field in its Engineering Aspects" Longmans London 1954 p139: “The current in the electrical circuit is a real flow of charged particles, and requires a continuous input of energy. The flux in a magnetic circuit, on the other hand, is not a flow of anything; it is an abstraction, devised to describe the magnetic state of the material. Energy is required to set up a magnetic field, but none is required to maintain it; otherwise permanent magnets could not exist.”

To resolve this problem, a magneto-dynamic circuit was needed; this would have to be a true analogue to the electric circuit. That resolution was slow to arrive, and has yet to appear in the text-books. There are several reasons for this reluctance.

UNITS

Oliver Heaviside coined the term “magnetic current” in “The Electrician” Feb. 13, 1891. Giorgi (upon whose system the SI is based) adopted this in his "Proposals Concerning Electrical and Physical Units" Trans. Int. Elect. Congress, St. Louis, 1904 pp136-141, in which he gives on p141 “Magnetic current (=dϕ/dt), absolute practical unit - volt” and “Mmf, absolute practical unit - ampere”. And it must have been clear that the product of the two is power. But the use of CGS units for magnetics and SI units for electrics has prevented the unification of electric and magnetic circuit theory. Those CGS units still persist.

SLOW UPTAKE OF COMPLEX PERMEABILITY

By the 1940s, Cauer had pretty much sorted electric circuit/filter theory. Magnetics lagged behind. The concept of magnetic loss was slow to appear; “vector permeability” was not codified until Mcfadyen’s paper of 1947, and it was not until Cherry’s "The Duality between Interlinked Electric and Magnetic Circuits and the Formation of Transformer Equivalent Circuits" Proc. Phys. Soc. B, Vol 62 No2, Feb 1949, pp101-111 that the full relationship between the electric and magnetic circuits became clear. You will note that Hamill’s papers of 1993-4, for all their correctness, deal only with reactive elements. (For a thoughtful treatment of the alternative lossy models, you might like to look at PG Blanken and JJLM Van Vlerken "Modeling of Electromagnetic Systems" IEEE Trans. Mag., Vol. 27, No. 6, Nov 1991, pp4509-4515.) By then, it was far too late, and the resistance-reluctance analogy was deeply embedded in thought and text books.

UNEASE ABOUT THE GYRATOR

The Tellegen Gyrator is a concept that remains classified as difficult, except for the Bond Graph community, which has accepted it as a founding tenet of the discipline. As Schlicke observed in his book “Essentials of Dielectromagnetic Engineering” of basic discontinuous material structures: “What seems magnetically a series arrangement is electrically a parallel circuit and vice versa.” and that the equivalent electric circuit is “… contrary to what the eye seems to see so clearly in the magnetic structure”.

PERSONAL COMPUTERS

The gyrator-capacitor approach only shows its real advantage when you have access to a circuit simulator, and it was not until about 1995 that they came within the reach of the ‘technologist on the street’.

Finally, if the gyrator-capacitor model were to be accepted for ‘the definitive’ magnetic circuit, then the magneto-static stuff would have to be solved using Laplace transforms; Hopkinson’s law has the merit of simplicity. Ninegam (talk) 10:37, 15 June 2015 (UTC)

Merge suggestion

It seems that the following articles relate only to this article: Magnetic impedance, Magnetic effective resistance, Magnetic inductance and Magnetic capacitivity. All four articles appear to be about specialized jargon that only applies to the Gyrator-capacitor model. I suggest that they be merged into the Gyrator-capacitor model article where they could benefit from common definition of terms and if seen together, it may all be easier to understand.

I also suggest that this article be given a different title that links it to magnetic circuit modeling, such as “Dynamic magnetic circuit model.” Gyrator-capacitor model could mean a simulated inductor or other gyrator based circuit element.

Finally, I hope that someone can add a picture or example to this article as Dr. Hamill’s paper is only available by purchase or subscription from the IEEE. Constant314 (talk) 15:59, 10 July 2016 (UTC)

I agree with your merge proposals. In standard circuit theory, the elements resistance, capacitance etc each have their own history and scientists who investigated them so quite rightly have their own articles. This model, on the other hand, was created all at once as a single lump of theory. Unless more information can be found beyond the definition of the elements and their circuit effects, then merging them here is the right choice.

I am not so sure about your proposed name change. The term dynamic magnetic circuit model gets only two hits on IEEE Xplore and it is not immediately obvious that either of them is referring to this model. I rather think they don't. Do you have any evidence that this is a recognised name of the model, let alone the common name? SpinningSpark 15:25, 5 August 2016 (UTC)

I have no evidence for any particular name. It just seems that something in the name ought to link to article to magnetic modeling. Hopefully, someone with more knowledge of the subject can come up with a better name.Constant314 (talk) 15:42, 5 August 2016 (UTC)

I don't think we should go against WP:COMMONNAME in this case, and gyrator-capacitor model does seem to be the name used in the literature. It would be possible to make the title more descriptive, such as gyrator-capacitor model of magnetic circuits, but that would be unnecessarily redundant and contrary to the general practice; Drude model is not self-evidently a model of conduction, mobility analogy is not self-evidently a model of electric-mechanical circuit analogies, and Copenhagen interpretation is not self-evidently a model of quantum mechanics. A better solution is to create a magnetic circuit models article or list from which the various relevant articles could be listed and found by users. Or if too short for its own page, create a section in magnetic circuit (which currently incorrectly gives the impression that there is only one possible analogy). SpinningSpark 01:18, 6 August 2016 (UTC)

I withdraw the suggestion to rename. It probably just needs an about template to direct someone looking for an article about gyrators to the appropriate article.Constant314 (talk) 18:30, 6 August 2016 (UTC)

I added an About template, but I'm not entirely sure what the article is about.Constant314 (talk) 15:26, 7 August 2016 (UTC)

The gyrator-capacitor model is an analogy between magnetic circuits and electrical circuits. It serves the same purposes as mechanical-electrical analogies. That is, it models an unfamiliar system in terms of a familiar (or better studied) one and allows a system with mixed energy domains to be analyzed as a unified whole. It is part of a wider group of analogies that cross energy domains. I mentioned the gyrator-capacitor model when I wrote the mechanical-electrical article and noted where it fits into this wider picture at mechanical-electrical analogies#Other energy domains. There is scope to widen out that section into a full article discussing analogies across all domains where the place of the gyrator-capacitor model can be better understood. The Busch-Vishniac source is especially useful for anyone wanting to take on this task. SpinningSpark 17:15, 7 August 2016 (UTC)

There is also Magnetic reactance. I recently came across the articles mentioned and independently came to the same conclusion both of you advocate: Magnetic impedance, Magnetic reactance, Magnetic effective resistance, Magnetic inductance and Magnetic capacitivity should be merged into this article. Go for it. --Chetvorno^TALK 19:50, 26 November 2017 (UTC)

There is also magnetic complex impedance. User:Sidam certainly likes to spread his work out thinly. SpinningSpark 16:10, 26 March 2018 (UTC)

 Done Klbrain (talk) 13:11, 29 April 2018 (UTC)

That's a nice mess, but well done for trying to tackle it. It has left the article with dozens of wikilinks back to itself. One of the few that actually goes to a different page is magnetic capacitance which should likely have been merged in as well. But what the article still really lacks is a clear statement of the basis of the analogy. I can't work up the energy to do anything about it right now. SpinningSpark 13:58, 29 April 2018 (UTC)

I also want to thank Klbrain for this work. I think probably all the red links refer to something in this article and could be removed. Constant314 (talk) 14:03, 29 April 2018 (UTC)

Dash

It seems that a gyrator capacitor is not a thing, so the hyphen makes no sense; rather, we should use an en dash to signify the and relationship, yes? Dicklyon (talk) 15:21, 29 April 2018 (UTC)

I don't know (nor do I care) about dashes, but I think you are right about the and relationship. As I see it, it is capacitor because reluctance in the reluctance model becomes a capacitor in the G-C model and a transducer between the electrical domain and magnetic domain in the G-C model is a gyrator because emf is produced by rate of change of magnetic flux, not by mmf which is emf's analog. SpinningSpark 16:08, 29 April 2018 (UTC)

Magnetic capacitivity

I'm having serious doubts that the "Magnetic capacitivity" is a real term. Since the definition given is a synonym of permeance, I have changed the title to that for now. The only book source I can get for the expression is this book on the properties of food—not the best source for an article on circuit theory (and their use of the term seems to mean reciprocal inductance; not the same thing). The -ivity ending of the expression suggests that it should be an intensive property, and thus a synonym for permeability, not permeance, an extensive property. The two sources in the article that was merged in are both foreign language, German and Russian. The two sources in Magnetic capacitance are also German and Russian. I'm inclined to put this down to a mistranslation of the sources. Busch-Vishniac, one of my go-to sources for electrical analogies, along with many other sources, confirm that magnetic capacitance, that is, the magnetic analogy of electrical capacitance, is the same as permeance.

I suggest doing the following,

1. Delete Magnetic capacitance as being complete rubbish. It is describing magnetic capacitive reactance, not capacitance.
2. Move Magnetic capacitivity to Magnetic capacitance along with its history. That gets the history under the right title.
3. Delete [[Magnetic capacitivity as being mistranslated term, and purge the term from the article.
4. Redirect Magnetic capacitance to Gyrator–capacitor model#Permeance.

SpinningSpark 16:58, 8 October 2019 (UTC)

None of the terms "Magnetic capacitivity", "Magnetic impedance","Magnetic effective resistance", "Magnetic reactance", or "Magnetic complex impedance" appears in Hamill's paper. I'm not sure that they belong in this article. Constant314 (talk) 19:28, 8 October 2019 (UTC)

Well let's deal with this issue first, which clearly has no support in any sources. Do you agree with my proposal? SpinningSpark 20:17, 8 October 2019 (UTC)

I don't have anything to go on, but I don't oppose anything that you proposed. Constant314 (talk) 21:44, 8 October 2019 (UTC)

Yes, I agree.Constant314 (talk) 04:21, 12 October 2019 (UTC)

Order of sections

Constant314, I don't agree with your move of the "Magnetic inductance" section. Your edit summary said this was to group the magnetic <foo> sections together. But all the elements of this analogy are magnetic somethings. It is more logical to keep magnetic inductance next to the magnetic capacitance section. That is, the permeance section, which I think should be renamed magnetic capacitance, but the issue I raised above needs sorting before that can be done. I think the order of sections should be this;

1. Gyrator – because this is the gyrator-capacitor model, so explain that first
2. Magnetic capacitance – same reason
3. Magnetic inductance – because it is the dual of capacitance
4. Magnetic impedance – because that is a concept derived from capacitance and inductance

There are a couple of other problems I'm having with this article. It is not clear to me what physical component is represented by "magnetic inductance". No argument that this is the correct analogy for electrical inductance, but how is one actually made? I note there is nothing equivalent to it in Hamill.

I think the magnetic impedance section should be left below the examples until it is cleaned up. It is needlessly repeating a lot of mathematical stuff that can be found in the electrical impedance article, and not making a very good job of it. It just litters the article with stuff that confuses rather than enlightens the reader. I'm beginning to think we should just have deleted all the articles on this subject created by User:Sidam instead of merging them here. Their stuff has just made improving the article ten times more difficult than it needs to be. SpinningSpark 10:12, 11 October 2019 (UTC)

I moved the Magnetic inductance section to get it out of the flow from Permeance to the Examples because I find it difficult and confusing. The reader should not have to slog through that to get to the example. Does magnetic inductance mean anything more than an inductance that might appear in the gyrator-capacitor model? If that is all it means, does it really need a name and a subsection? I want to reply to the rest of your comment, but real life is intruding today. Constant314 (talk) 19:09, 11 October 2019 (UTC)

I think the Permeance section should retain that name, because permeance is the physical quality being modelled, even if the model happens to be an electrical capacitor. In a text book, it may be logical to group Magnetic capacitance, inductance, impedance together so that they could be treated from within a common framework. But consider the poor reader who just wants to know what the gyrator-capacitor approach is. Give him the minimum it takes to understand the model: chucks of steel (permeances) and windings (gyrators). Push the advanced stuff to the end.

How about this order:

1. Example
2. Gyrator
3. Permeance (a.k.a. magnetic capacitance)
4. Magnetic inductance
5. Magnetic impedance.

That would keep the logical sections together, but the reader who just wants to know what the model is about can stop with Permeance without the frustration of making sense out of the rest of the article. Just asking, do the terms magnetic capacitance, magnetic inductance, magnetic impedance occur in the literature outside the gyrator-capacitor model? I have further thoughts about magnetic inductance, but I’ll save those for later. By the way I will request copies of reference 2 and 3, if you want to piggy back a request. Constant314 (talk) 05:13, 12 October 2019 (UTC)

That order doesn't work for me. One needs to explain the analogy and its elements before giving an example of it. On the section title, I favour "magnetic capacitance" because all the other sections are the names of the model element, not the physical property giving rise to them. The link to permeance would need to be in the first sentence of course. However, I can live with "Permeance" as a heading. SpinningSpark 08:21, 12 October 2019 (UTC)

Changed order per User:Spinningspark's suggestion. Constant314 (talk) 23:00, 12 April 2020 (UTC)

Magnetic inductance

I’m starting to get a grip on magnetic inductance. The energy it stores would be, by duality, energy stored in the electric field. The permeance elements guide a time varying magnetic flux (charge on the magnetic capacitance). That would be accompanied by a time varying electric field that would wrap around the permeance in the same direction as a winding. That electric field would store energy in the permittivity of the permeance (probably close to vacuum permittivity). The electric field would also penetrate the permeance where it would cause eddy currents. That, to me, at least, gives a physical effect related to magnetic inductance and resistance. Constant314 (talk) 08:44, 12 October 2019 (UTC)

(posted before I saw the above comment) I'm not seeing any source that uses the term "magnetic inductance" to mean anything other than plain ordinary inductance. So is there such a thing? Inductance arises because an electric current gives rise to a magnetic field (Ampere's circuital law). There is no magnetic analogy to this because a current of magnetic monopoles doesn't exist. However, a changing electric flux also gives rise to a magnetic field (this is Maxwell's displacement currents). There is clearly analogy to this; Faraday's law of induction. But it is still not clear to me where that would need to be represented in the modeel. Obviously, Faraday's law is at work at the transducer between the electric and magnetic domains, but that is what we are using the gyrator to represent.

It's not clear to me that there is any passive phenomenon within the magnetic circuit (ie away from the transducers) that needs to be modelled with an inductance. The bottom line is that, so far, there are no sources to go on, so the section should not really be a separate section. At most a mention in the impedance section when discussing the sign of magnetic reactance. SpinningSpark 08:53, 12 October 2019 (UTC)

Recent changes to table

@Ahri6279: I haven't checked everything you have done here, but I'm not convinced that you understand this model. You seem to be reverting the article to a reluctance-resistance model as described in magnetic circuit. Magnetic resistance is a redirect magnetic reluctance and that is not analogous to electrical resistance in this model. Also, pairing electric current with the fictitious magnetic current is not helpful in developing a circuit model. Magnetic flux rate of change exists and that is what electric currents should transform into. SpinningSpark 10:12, 31 March 2020 (UTC)

I guess my fantasy for this table would have three horizontal groups. The first would have a physical quantity like flux, the second would have to resister-reluctance analog and the third would have the gyrator-capacitor analog. For instance, flux would be physical, current would be the RR quantity and charge would be the GC quantity. In the old table, there was a mix of physical and RR terms on the left. The new table has eliminated that but has become useless. It is just a list of field and circuit quantities with the adjective magnetic on the left and electric on the right. In its present form, I would advocate deleting it. Constant314 (talk) 14:53, 31 March 2020 (UTC)

"Magnetic capacitivity" listed at Redirects for discussion

An editor has asked for a discussion to address the redirect Magnetic capacitivity. Please participate in the redirect discussion if you wish to do so. SpinningSpark 13:54, 1 April 2020 (UTC)

Permeance title (again)

We really can't have the article constantly switching between "permeance" and "magnetic capacitance". We need to use either one term or the other throughout and just state once the terms equivalence. We especially can't have Permeance as the heading when Cm is used as the symbol. It's all just too confusing for the reader. SpinningSpark 23:32, 3 April 2020 (UTC)

I see your point. I understand that it is inconsistent. I have two concerns. First, Hamill calls it a "permeance". Second, I feel like the entire article is confusing until you hit the examples. I would like to minimize the material before the examples. I propose this: rename "permeance" as "magnetic capacitance (permeance)". Move that section and gyrator after the examples. Constant314 (talk) 00:29, 4 April 2020 (UTC)

I'm happy with just "Permeance" as a title, but if we keep that, we really need to purge the multiple references to capacitance and the symbols. Just explain once that this is the "magnetic capacitance" in the model. On the order of sections, can we deal with just one of the many problems this page has at a time. There is already a thread open on that further up the page. SpinningSpark 06:55, 4 April 2020 (UTC)

How about if I add a figure to the lede showing a simple transformer and it G-C equivalent. It will only use elements mentioned in the lede. That will satisfy my concern that the definitions make better sense if a picture comes first. Then the example can be moved after the definitions.Constant314 (talk) 03:26, 5 April 2020 (UTC)

As I said, the order of sections issue can do nothing to address the issue I've raised here. Mixing the discussions just makes this harder than it needs to be to get anything done. SpinningSpark 07:49, 5 April 2020 (UTC)

I understand that it is confusing. The literature is confusing. Constant314 (talk) 08:04, 5 April 2020 (UTC)

Magnetomotive force or difference in magnetic scalar potential

The magnetic capacitance definition uses the difference in magnetic scalar potential, ϕ₂-ϕ₁. All the other definitions use magnetomotive force, F. It seems that the magnetic scalar potential is used mainly with permanent magnet situations, so I would like to change the magnetic capacitance definition over to magnetomotive force. Constant314 (talk) 17:52, 11 April 2020 (UTC)

I think the editor was trying to draw an analogy with electrical potential difference. The mmf is analogous to emf and only occurs where there is a source of "magnetic voltage", such as at a winding. The magnetic potential exists all round the circuit, just like voltage does in an electric circuit. SpinningSpark 11:34, 15 April 2020 (UTC)

If there is no objection, I will change it to mmf. Constant314 (talk) 13:10, 15 April 2020 (UTC)

My comment above is implicitly an objection. We wouldn't use emf in the definition of electrical capacitance, we'd use potential difference or voltage, so why do something different here? Especially as we are supposed to be presenting an analogy, we should do things in an analogous way. SpinningSpark 15:41, 15 April 2020 (UTC)

Whether it is difference in potential or mmf doesn’t matter to me, but I would like to be consistent within the article. Magnetic impedance and the chart use mmf. Magnetic capacitance is the only use of potential. Among the references that I have, the word potential does not occur in Hamill, Lambert, Yan, and Kaushal but they do have mmf. Potential, mmf and magnetic voltage are used interchangeably by Gonzalez and Mohammod. Among those refences, only Gonzalez and Mohammod define magnetic capacitance. They both expressly use the line integral of the H field, which is the definition of mmf. So, for consistency within the article and with the sources I have, I would like to replace the difference in magnetic scalar potential with mmf in the one place it occurs. Constant314 (talk) 16:58, 15 April 2020 (UTC)

Ok, you've convinced me. Buntenbach doesn't refer to magnetic potential either. SpinningSpark 21:19, 15 April 2020 (UTC)

Component/eleement and capacitor/inductor

Constant314, you're doing a grand job on sorting out this article (and I should be helping but don't have the energy to tackle this mess) but I do have a couple of comments,

1. The terms component and circuit element are not synonymous and there is frequently not a one-to-one correspondence.
2. It is not correct, or at least highly misleading, to say that a magnetic inductance is equivalent to an electrical capacitance. Magnetic inductance is analogous to electrical inductance in this model. A magnetic inductance transforms into an electrical capacitance if taken through a "gyrator" transducer. Taking it through a "transformer" transducer results in an inductor/inductor transform. Also, the value of the transformed element depends on the gyrator/transformer transfer impedance/ratio, so "equivalence" is a moving target.

I am also bothered that the "resistance-reluctance" heading in the template has acquired a wikilink to magnetic circuit. That article cannot be both the general article on magnetic circuits and the specific one for that model (unless the model was clearly separated into its own section). See also my comment on the template talk page. SpinningSpark 11:34, 15 April 2020 (UTC)

I have attempted to address all your points.Constant314 (talk) 13:11, 15 April 2020 (UTC)

Magnetic inductance – Looking for sources

I am looking for sources, hopefully that can be obtained form the internet, that discuss magnetic inductance. I only have Mohammad and Gonzalez and Mohammad seems to be repeating Gonzalez. Their treatment considers that a magnetic inductor is just an ordinary capacitor gyrated into the model magnetic circuit. Mohammad goes so far as saying that the magnetic capacitor “will not be considered as a magnetic element.” Constant314 (talk) 11:29, 18 April 2020 (UTC)