Magnetic Field Intensity At the Inductor's Air Gap (+Fringing Flux)

In summary, the conversation discusses the issue of altering the BH curve in a switching power supply and the use of an air gap at the transformer's core to prevent core saturation. The person mentions reading a paper and deriving formulae to solve the problem, but notices a mismatch in one of the equations. They also mention a possible typo in the paper and ask for clarification on a term in the derivation.
  • #1
BlackMelon
43
7
Hi there!

Sorry for the unclear images in the previous post. This time I upload pdf files for my derivation and the reference paper.

So, when I design a switching power supply, usually I make an air gap at the transformer's core. This will alter the BH curve, preventing the core saturation. However, as I increase the gap's length, the fluxes fringes. So, the reluctance of the air gap is not high enough to alter the BH curve as I expected.

To solve the problem, I read a paper by Roshen (file Roshen2007.pdf) and derive formulae inside that paper (file Formulae Derivation... .pdf).
I got a mismatch of scalar potential function (equation II.6 in both files).

On the last page of my derivation, I got a term Hg*y/2.
On the second page of Roshen's paper, this term is Hg/lg

I would like to know why Roshen did not put the variable y on that term?

Best Regards,
BlackMelon
 

Attachments

  • Formulae Derivation_Fringing Field Formulas and Winding Loss Due to an Air Gap.pdf
    1.6 MB · Views: 56
  • roshen2007.pdf
    1.1 MB · Views: 56
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  • #2
Looks to me like a typo in Roshen, but I couldn't follow the expansion completely.
 
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  • #3
Charles Link said:
Looks to me like a typo in Roshen, but I couldn't follow the expansion completely.

May I know which part of my expansion is confusing?
 
  • #4
BlackMelon said:
May I know which part of my expansion is confusing?
I don't have much expertise at doing the LaPlace expansions, both the integer one, and the continuous one. I'm somewhat familiar with the Legendre type method of solution, and I think this one is similar to that, but I have little expertise with it.
 
Last edited:

What is magnetic field intensity at the inductor's air gap?

Magnetic field intensity at the inductor's air gap refers to the strength of the magnetic field that is present at the gap between the inductor's core and its surrounding air. It is measured in units of Tesla (T) or Gauss (G).

Why is magnetic field intensity at the inductor's air gap important?

Magnetic field intensity at the inductor's air gap is important because it affects the performance and efficiency of the inductor. It determines the amount of flux that passes through the inductor's core, which in turn affects its inductance and ability to store and transfer energy.

How is magnetic field intensity at the inductor's air gap calculated?

Magnetic field intensity at the inductor's air gap can be calculated using the formula H = B/μ, where H is the magnetic field intensity, B is the magnetic flux density, and μ is the permeability of the material. It can also be calculated using experimental methods such as the Hall effect or magnetic field probes.

What is fringing flux and how does it affect magnetic field intensity at the inductor's air gap?

Fringing flux refers to the magnetic field lines that extend beyond the edges of the inductor's core and into the surrounding air. This can affect the magnetic field intensity at the air gap, as it increases the total amount of flux passing through the gap. Fringing flux can be minimized by using a larger core or by adding a magnetic shield around the inductor.

How can magnetic field intensity at the inductor's air gap be controlled?

Magnetic field intensity at the inductor's air gap can be controlled by adjusting the inductor's core material, shape, and size. It can also be controlled by varying the amount of current passing through the inductor or by using magnetic shields to redirect the fringing flux. Additionally, the distance between the inductor's core and the surrounding air can also affect the magnetic field intensity at the air gap.

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