Question on inductance with magnetic material core.

[yungman]

Is there a difference in inductance of an inductance with magnetic material whether it is magnetized or not. Meaning is there an increase of inductance if the core has been magnetized ( become magnet) vs the same material but not magnetized?

Does magnetization increase the $\mu$ of the material?

 

[cabraham]

Yes.

 

[yungman]

Yes.

So the stronger the magnetization, the higher the $\mu$? How much difference.

Is it true that if I have an inductor with a iron core. I can increase the inductance by putting a magnet near it to induce magnetism onto the core? And the stronger the induction, the higher the inductance.

Can someone point me to reading materials in this subject?

Thanks

Alan

 

[cabraham]

Near the origin is "hard magnetization". As the winding current increases, the flux increases non-linearly since mu increases. Then mu is roughly constant as amp-turns increase & flux increases linearly. This region is "easy magnetization". Then as the saturation flux density value is approached, mu decreases. THe curve, known as the "B-H loop" is non-linear.

For reading materials, any good e/m fields text is recommended. Kraus & Carver, Griffiths, Hayt, are 3 that come to mind, but there are others as well. Also, makers of xfmr & inductor core material like Philips magnetics, Arnold Engr., Magnetics Inc., are good resources. They know magnetic materials better than anybody. That should get you started.

Claude