STEORN DEMO LIVE & STREAM in Dublin, December 15th, 10 AM

[0c]

Equations are found in University and various other books and software such as FEMM. Equations provided in the open-sourced software, FEMM.  Evidence: experiments & FEMM. That's all I can do for you since it's not worth the time to create FEMM files to show you very fundamental physics.

Paul, I have a number of those textbooks and a lot of industry literature. The thoughts I posted are based on that literature. I'm afraid I don't have the math background to do more than simple algebraic calculations, but I can follow the dynamic relationships pretty well.

If you would take some time to consider some of the the properties I mentioned, you may see that they too can influence the overall behavior. High permeability is one of the desired characteristics. But by no means is it the only one.

For the sake of further discussion, let's talk about remanence for a moment. A high remanent magnetization will provide a magnetic bias that reduces the DC input energy costs to saturate the core.

Using longitudinally annealed Metglas 2714AS as an example, we see it has a Bsat of 0.57T and a Br of 0.45T, for a Br/Bsat ratio of about 79%. That's pretty high compared to most materials.
(page 3 of: http://metglas.com/downloads/magamp.pdf )

Now compare that with Finemet FT-1H, which has Bsat of 1.35T and Br of about 1.21, for a Br/Bsat ratio of 90%.
(page 8 of: http://www.hilltech.com/pdf/hl-fm10-cFinemetIntro.pdf )

The Finemet will retain 90% of its magnetization when the coil is deenergized where the Metglas will only retain 79%. Which material will require more input energy to push into saturation?

[happyfunball]

ttp://www.youtube.com/watch?v=U-8dmfEkR-E

This seems rather interesting. What do you figure the draw of those LED's might be

[wings]

For the sake of further discussion, let's talk about remanence for a . A high remanent magnetization will provide a magnetic bias that reduces the DC input energy costs to saturate the core.
The Finemet will retain 90% of its magnetization when the coil is deenergized where the Metglas will only retain 79%. Which material will require more input energy to push into saturation?

translating into simple concepts:
the remanence is the ability to retain a magnetic polarity.

this can help the motor torque only when the next magnet have inverted magnetic polarity, otherwise you reduce the DC input energy but you reduce also the attraction force.

in any case you have energy loss in the core (heating).

the best solution is to have an "elastic" property when the magnet approach the spin becomes aligned with the magnetic field, then with the coil current you flip the spin alignment along the toroid core and saturate the core (it appear like air to the magnet).

The challenge is to have the new spin alignment with gain of energy that recover the work of alignment done by the magnets.

metglas annealed along the core have the possibility to do this job?.

[gravityblock]

I agree completely here. Good explanation.

In SeanM's own words - "Core material is not important for the orbo effect, any material will work as long as it is a soft ferromagnetic material". (Quoting from memory, you will find the exact words on steorn forum).

If my memory serves me correctly, his words were "The core material is a soft magnetic material, I will not go into the details, sorry".

If he's not going into the details, then the details are important for the Orbo effect.  The details of the core material is important, because the linear portions in the M-H Curve must be large enough for the magnetic field from the dual magnets to sit on due to the DC Pulse biasing it to that position.

GB

[gravityblock]

translating into simple concepts:
the remanence is the ability to retain a magnetic polarity.

this can help the motor torque only when the next magnet have inverted magnetic polarity, otherwise you reduce the DC input energy but you reduce also the attraction force.

If the field from the magnets sit on the linear portions of the M-H Curve of the core material when the pulse is applied, then the attraction force is not reduced while keeping the torque at it's maximum, but the DC input energy will be reduced.  How many times do I need to say what is in bold.  I will say it as many times as necessary for this to sink in, if that is possible.

GB