Dear Senthil Ram Nagapillai Durairaj,

Honestly, I have never seen a relationship between these three properties Hc, Br, and Ms. Although they are the most basic on a hysteresis curve and have settled when we have Ms (maximum), they still change with the evolution of the magnetization for different values ​​of maximum applied field, as you can see in the curve, only the last curve shows the three values ​​(Hc, Br and Ms) well established, so that if Hmax >> Hs for the next cycle, values remain unchanged.

Since Hc, Br, and Ms are properties, they depend on each material, so I believe only one empirical formula to solve their problem. I researched a lot and could not find a relationship between them, only empirical, but for other materials. The easiest way is to perform magnetization measurements via VSM (Vibration Sample Magnetometer) or AGFM (Alternative Gradient Field Magnetometer) magnetometers. Now a scalar calculation that relates the three I do not know. Success in your research and any questions we are here.

Oreci Escobar Da Silva Thank you for the information, I came across an emprical formula BHmax = (µoMs^2)/4

Is this approach is valid?

Senthil Ram Nagapillai Durairaj This expression is valid (hopefully right for your material), being similar to that in the reference, at a glance.

Reference: Novel Functional Magnetic Materials: Fundamentals and Applications edited by Arcady Zhukov

I have spent a lot of time thinking about the opposite question, given a certain value of Ms, what are the limits on Br, Hc and (BH)max?

One thing to keep in mind is that Ms is an intrinsic property, where as all the others are extrinsic, i.e. influenced by processing. This makes my question a bit easier, and yours a bit more difficult. (I think!)

If I were trying to estimate Ms from available parameters, I would use Br as the important parameter. With some experience, you may be able to find an appropriate factor to employ for the specific class of magnet of interest to you. Br will always be some fraction of mu0Ms, hopefully close to 100%, and if it consistent, then you can use the factor to estimate Ms from Br. But I would be very careful about using this factor, since it is likely to change with different materials. A factor found for sintered NdFeB won't likely apply to bonded NdFeB, and so on. I'd expect its applicability to be limited.

However, if I really needed to know Ms, I would just measure it, which really isn't too difficult, and the result would be less in doubt.

If you don't mind, I'm curious where you are going with this information. What would you like to do with the Ms of a permanent magnet that you need to its value?

Stan Trout i've designed a magnet to control the leakage flux on the surface of the magnet from one pole to other pole. To study the behaviour of the flux and flux density on the surface of the magnet, i need to seek the value of Ms . Please find the magnet design and need to find out the variation of |B|, B.n & B.t on the surface of the cavity. The Magnet is called Super Ellipsoidal Cavity Magnet

Senthil Ram Nagapillai Durairaj Thanks for sharing your picture, Senthil. What would be so wrong in just using Br? Do you have a specific application in mind for this magnet?

Stan Trout I don't think so it is wrong, using Br and Ms has a very less significant change in the value of surface flux density parallel to the direction of magnetization. Yes, this magnet has been specifically design for Claw pole interpole magnets for alternator and BSG

Senthil Ram Nagapillai Durairaj, when you locate your formula ( BHmax = (µ0MS2)/4 ) in the text Oreci Escobar Da Silva provided, then you will find that it is the result for a poor M(H) loop!! Not what you're looking for, I'd guess.

I would second Stan Trout's statement that HC is not an intrinsic quantity not even when you're on a major loop. The reason is that HC is tied to the mechanism of magnetization reversal. As Stan wrote, it will depend on material processing - let me add that it will also depend on magnet size & shape.

Hello Senthil Ram Nagapillai Durairaj ,

Interesting calcualtions.

You can use this excell sheet here to automatic calculate the values for B(z) at different distances, magnets grades and for various magnets geometry:

https://media2.supermagnete.de/docs/supermagnete_flux_density_eng.xls

For calcualations away the magnetization axis z-axis on symmetrical magnets, I thing the most convenient is to use a a s/w application like this here:

http://www.femm.info/wiki/HomePage

or wolfram alpha:

https://www.wolframalpha.com/examples/science-and-technology/physics/electricity-and-magnetism/

For the super ellipsoid cavity calculations should not be that different from the arc magnet. A good approximation for the far field of this magnet , besides your very good patent,

Patent SUPER ELLIPSOIDAL CAVITY MAGNET FOR CLAW POLE ELECTRICAL MACHINE

I believe is this paper:

Article Magnetic field calculation of claw pole permanent magnet mac...

Just one question for you?

In your attached in your previous message calculations pdf for the arc magnet you calculate in a value Br=0.42 , where did you find this?

You assume a ferrite Y35 grade magnet?

Look at this table here:

https://www.supermagnete.de/eng/data_table.php

Br is not depended on geometry of magnet but only on physical material properties and magnetization process applied.

Also for magnetic scalar potential calculations use this:

https://www.wolframalpha.com/input/?i=magnetic+scalar+potential+of+a+rectangular+bar+magnet&lk=3

or current loop:

http://demonstrations.wolfram.com/MagneticFieldOfACurrentLoop/

Kind Regards,

Emmanouil Markoulakis

Technological Educational Institute of Crete

Emmanouil Markoulakis

Sorry for the delayed reply, I was working on the part of magnetic field calculation outside the magnet of the Super ellipsoidal Cavity Magnet. Please find the reference chart by which, the calculated magnetic flux density and simulated flux density using FEMM. The result of the both the result does not correlate, SoI'm trying to figure out

Please share your thought

Senthil Ram Nagapillai Durairaj

For a simple magnet say, a cube nd N42, do the plots match?

If yes, assuming you correctly insert the simulation parameters in the sim,

then it must be something with your calculus.

Check also the simulation warnings... maybe the sim has a limitation or you triggered a parameter warning in the sim.

Did you correctly added the Br value for Y35 ferrite magnet? thus 0.40-0.41.

Also be extra careful with the units of your input data in the sim, convert to the accepted unit system when needed.