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)