How does a ferromagnet increase the inductance of an inductor?

In summary, the effect of adding a constant magnetic field, or a DC bias flux, to an inductor is to increase its inductance. This is due to the concept of Magnetic Permeability, which acts as a sort of "fly wheel" to push against the changing magnetic field and increase the overall inductance. This is a first order effect, and in real world applications, the non-linear B-H loop of core materials can have a significant impact on the inductance.
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Jaccobtw
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Inductance according to Faraday's law depends on a changing magnetic field. The magnitude of the induced emf depends on the magnitude of change in the magnetic field per change in time. Based on that, how does adding a constant magnetic field (a ferromagnet), increase the inductance of an inductor?
 
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The key is Magnetic Permeability. I always thought of it as adding a kind of fly wheel to the inductor - something to push against.
 
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Since this is the same question you asked in your other thread. I'll refer you to my same answer. Do you need us to elaborate?

Jaccobtw said:
OK I think I understand. The direction the inductor is wound will affect the direction of the magnetic field inside the inductor (or at least this is what I've concluded using the right hand rule), but it doesn't change the back emf.

So what about placing a magnet inside of the inductor? How does this increase inductance? If inductance depends on a changing magnetic field, how does placing a constant magnetic field inside an inductor increase inductance?
 
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.Scott said:
The key is Magnetic Permeability. I always thought of it as adding a kind of fly wheel to the inductor - something to push against.
No, the OP isn't asking about permeability. He's asking about a DC bias flux added to the core and its effect on inductance.

PS: Note that this is based on "first order" effects, i.e. basic understanding. In fact a DC bias on cores does have, sometimes significant, effects because most core materials have a very non-linear B-H loop as used in real world applications.
 
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1. How does a ferromagnet affect the inductance of an inductor?

A ferromagnet can increase the inductance of an inductor by increasing the magnetic flux through the inductor's core. This is because the presence of a ferromagnet can amplify the magnetic field produced by the inductor, resulting in a higher inductance value.

2. Why is a ferromagnet used in inductors?

Ferromagnets are commonly used in inductors because they can significantly increase the inductance of the inductor without requiring additional turns or lengthening the core. This allows for more compact and efficient inductor designs.

3. How does the shape of a ferromagnet affect the inductance of an inductor?

The shape of a ferromagnet can affect the inductance of an inductor by altering the path of the magnetic flux through the core. A longer or wider ferromagnet can provide a longer path for the flux, resulting in a higher inductance value.

4. Can a ferromagnet decrease the inductance of an inductor?

In some cases, a ferromagnet can decrease the inductance of an inductor. This can happen when the ferromagnet saturates, meaning it reaches its maximum magnetic flux density and can no longer increase the inductance of the inductor.

5. Are there any disadvantages to using a ferromagnet in an inductor?

While ferromagnets can increase the inductance of an inductor, they can also introduce non-linearities in the inductor's behavior. This can lead to distortion in the output signal, which may be undesirable in certain applications. Additionally, ferromagnets can be prone to demagnetization, which can decrease their effectiveness in increasing inductance over time.

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