Model an Inductor: Flux Through Core & Air Around It

In summary, the conversation discusses how to model the ideal inductor and the reasons for placing the leakage inductance in series with the ideal core rather than in parallel. The speaker explains that this is because the same current creates both the magnetizing and leakage fluxes, making it necessary to model Lk and Lm as series-connected elements. Another speaker adds that the concept of leakage flux applies more to transformers rather than isolated inductors, but there is still a leakage inductance in series with the primary. It is suggested to lump them together for practical purposes.
  • #1
tim9000
867
17
Hi, I'm just curious why we model the ideal inductor as having the leakage inductance as being in series with the ideal core, rather than in parallel to it? Because it would seem to me that the flux goes in two parallel directions, one through the core, and one through the air around the core. Please observe my illustration of what I mean:
snip.PNG
 
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  • #2
The same current creates both the magnetizing and leakage fluxes. That means you need to model Lk and Lm as series-connected elements.
 
  • #3
berkeman said:
The same current creates both the magnetizing and leakage fluxes. That means you need to model Lk and Lm as series-connected elements.
Good point!
 
  • #4
tim9000 said:
Good point!
Leakage flux seems to apply to the case of a transformer, where part of the primary flux does not link to the secondary. I don't think it applies to an isolated inductor. If a perfect transformer has a resistor across the secondary, the primary looks like a resistor. But in practice, there is still a leakage inductance in series with the primary.
 
  • #5
tech99 said:
Leakage flux seems to apply to the case of a transformer, where part of the primary flux does not link to the secondary. I don't think it applies to an isolated inductor. If a perfect transformer has a resistor across the secondary, the primary looks like a resistor. But in practice, there is still a leakage inductance in series with the primary.
As you say, it would be of limited use, accurate modeling, but just as useful to lump them together in that case.
 

1. What is an inductor?

An inductor is an electronic component that stores energy in the form of a magnetic field. It consists of a wire wound into a coil, typically around a core material such as iron or ferrite.

2. How does an inductor work?

When an electrical current flows through the wire coil of an inductor, it creates a magnetic field around the coil. This magnetic field can store energy and will resist changes in the current, causing it to oppose any changes in the electrical circuit.

3. What is flux?

Flux is a measure of the amount of magnetic field passing through a given area. In the context of an inductor, it refers to the magnetic field passing through the core material and the air surrounding it.

4. Why is the flux through the core important?

The flux through the core is important because it is directly proportional to the amount of energy that can be stored in the inductor. The more flux passing through the core, the greater the energy storage capacity of the inductor.

5. How is the flux through the core and air around it modeled?

The flux through the core and air around it can be modeled using the concept of magnetic flux density, which is a measure of the strength of the magnetic field in a given area. This can be calculated using the inductance of the coil, the number of turns in the coil, and the current flowing through the coil.

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