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
45
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: 93
  • roshen2007.pdf
    1.1 MB · Views: 82
Physics news on Phys.org
  • #2
Looks to me like a typo in Roshen, but I couldn't follow the expansion completely.
 
  • Like
Likes BlackMelon
  • #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:

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

What is magnetic field intensity in the context of an inductor's air gap?

Magnetic field intensity, often denoted as H, in the context of an inductor's air gap refers to the strength of the magnetic field within the air gap. It is a measure of the magnetomotive force per unit length and is influenced by the current flowing through the inductor and the geometry of the core and air gap.

How does the air gap in an inductor affect the magnetic field intensity?

The air gap in an inductor affects the magnetic field intensity by introducing a region with much lower permeability compared to the core material. This causes a drop in the magnetic flux density (B) across the gap, but the magnetic field intensity (H) increases in the air gap due to the lower permeability. The presence of the air gap also helps to linearize the inductor's behavior and prevent core saturation.

What is fringing flux and how does it relate to the air gap in an inductor?

Fringing flux refers to the spreading out of magnetic field lines at the edges of the air gap in an inductor. This occurs because the magnetic field lines do not remain confined within the core and the air gap but tend to bulge outward. Fringing flux can lead to increased magnetic field intensity at the edges of the air gap and can affect the overall inductance and performance of the inductor.

How can fringing flux be minimized in an inductor's air gap?

Fringing flux can be minimized by designing the inductor with a smaller air gap length, using magnetic materials with higher permeability to better confine the magnetic field lines, and employing geometric shapes such as chamfered or tapered edges at the air gap to reduce the bulging effect. Additionally, using a distributed air gap, where the gap is spread over multiple small sections, can also help to reduce fringing effects.

Why is it important to consider magnetic field intensity and fringing flux in inductor design?

Considering magnetic field intensity and fringing flux in inductor design is important because these factors influence the inductance, efficiency, and thermal performance of the inductor. High magnetic field intensity in the air gap can lead to core saturation and increased losses, while fringing flux can cause non-uniform magnetic fields and affect the inductance value. Properly accounting for these aspects ensures the inductor operates efficiently and within its design specifications.

Similar threads

Calculating flux density in an air gap
Replies
1
Views
4K
I Mutual inductance in a transformer
Replies
16
Views
3K
Calculating Flux from a Permanent Magnet
Replies
1
Views
6K
Flux and Current of Magnetic Core With Air Gap
Replies
13
Views
3K
Calculating the magnetic field of a closed magnetic circuit
Replies
1
Views
2K
Solving the operating point of a transformer with a nonlinear B-H curve
Replies
4
Views
1K
How Does a Toroidal Coil's Magnetic Field Change with an Air-Gap Insertion?
Replies
4
Views
7K
Calculating Magnetic Flux in Spool Coil with Air Gap - Formula and Example
Replies
5
Views
2K
Magnetic flux in tap changing transformers
Replies
5
Views
4K
Engineering How to Calculate Reluctance and Estimate Force in a DC Electromagnetic Actuator
Replies
1
Views
3K

Hot Threads

Recent Insights

Back
Top