Ferrite Core Inductor : Working, Types, Calculation, Losses & Its Applications

The inductor is an electronic component used to store electrical energy within the magnetic field once electrical current is supplied throughout it. Inductors are normally made into a coil with an insulated wire wound. Whenever current is supplied throughout this coil from the left to right side, a magnetic field is generated in the clockwise direction. So, inductors will resist any change within the current flowing throughout them. Generally, inductors are available in three types air core, iron core, and ferrite core. The air & iron core type inductors simply carry minimum frequency operations, higher losses & low inductance whereas the ferrite core inductor has high permeability, high inductance & fixed value. So this article provides brief information on a ferrite core inductor – working with applications.

What is Ferrite Core Inductor?

A ferrite core inductor definition is, a two-terminal passive electrical component used to resist changes in the electric current flowing through it. This inductor uses a ferrite material like the main core which has high electrical resistivity & high magnetic permeability. While using ferrite cores within inductors, different factors need to consider like high saturation, high impedance, fewer losses, stability within temperature & material properties. So it is usually used with power suppliers and power management applications. The ferrite core inductor symbol is shown below.

We know that in a ferrite core inductor, ferrite material is used like a core. So the ferrite’s general composition is XFe2O4, where ‘X’ signifies transition material. Generally, ferrites used in inductors are available in two types soft ferrites & hard ferrites.

Soft ferrite materials have the capability to overturn their polarity without any outside energy.
Hard ferrites are permanent magnets where polarity will not vary even once the magnetic field is detached.

Ferrite Core Inductor Working Principle

Ferrite core inductor works by allowing the flow of current to generate a magnetic field & the change within the magnetic field results in the flowing of an opposing current. So they change the energy from electrical to magnetic and store the energy within them.

Ferrite core inductor uses ferrite core material which is one type of magnetic core made with ferrite. Once these metal cores are utilized in these inductors, then the changing magnetic field will exhibit large eddy currents due to the electrical conductivity of the core (metal). So these currents flow in the inductors along with the closed-loop of current.

The role of ferrite core in these inductors is to help in improving the inductor performance by simply providing maximum permeability to the coil to increase their inductance & magnetic field.

Generally, the range of permeability within the ferrite core inductors ranges from 1400 to 15,000 based on the ferrite material type utilized. So, these inductors have high inductance as evaluated with other types of inductors by air cores.

How to Calculate the Inductance of a Ferrite Core Inductor?

In Ferrite inductors, the term Ferrite is a set of ceramic materials including some strong electromagnetic properties like high permeability in combination with low electrical conductivity.

A simple ferrite inductor can be designed by wrapping a minimum of 20 turns of wire around a ferrite rod. So the inductance of a ferrite rod can be measured with the help of an inductance meter. Here, inductance is denoted with ‘L’ and the numbers of turns are indicated with “N.”

Now calculate the ferrite inductor’s AL value.  Here the value of ‘AL’ is the base relationship between the inductance by a specified ferrite core & the no. of turns. The following formula is used to calculate the AL value.

AL = [(100/N)^2)] x L.

For instance, if you measured the ‘L’ value in Step-1 as 15 uH, then the equivalent ‘AL’ value will be:

AL = [(100/20)^2] x 15uH =( 5^2) x 15uH = 25 x 15uh = 375 uH.

The following formula is used to calculate the inductance (L) value by using the AL value for ‘N’.

L = AL/[(100/N)^2].

For instance: If N is 10, L = 375/[(100/10)^2] = 375/[10^2] = 375/100 = 3.75uH.

If N = 20, L = 375/[(100/20)^2] = 375/[5^2] = 375/25 = 15uH.

From above we can notice that when N increases then the inductance will be increased. This is mainly due to placing a number of wire turns around a loop, and then it focuses the magnetic field into a minor space, wherever it can be more efficient & produce more inductance.

Ferrite Core Inductor Characteristics

The ferrite core inductor characteristics include the following.

• Ferrite core inductors have low eddy current losses, high electrical resistivity, and high permeability. So these characteristics will make these inductors to use in high-frequency applications.
• In these types of inductors, the flow of current will generate a magnetic field as well as the variation within the magnetic field will result in the flowing of an opposing current.
• They change the energy from electrical form to magnetic & store this converted energy within them.
  They permit Direct currents but not Alternating currents to flow throughout them at maximum frequencies.
• They have high-quality factors, minimum stray field, high inductance, and performance over temperature.

Losses

Ferrite core inductors exhibit losses like eddy current and hysteresis. These inductors mainly depend on frequency levels. In this type of inductor, the eddy current losses exponentially increase whereas the hysteresis losses linearly increase with the increase in flux & frequency.

Out of these two losses in this inductor, the hysteresis loss is the leading one however up to a level of frequency that depends on the core’s performance, beyond which eddy current loss is in the majority.

Advantages and Disadvantages

The advantages of ferrite core inductors include the following.

• The ferrite core inductors can be operated at high & medium frequencies.
• This inductor has fewer eddy current losses.
• These inductors play a significant role in controlling different parameters like hysteresis loss and temperature coefficient by the adjustment of the air gap.
• They provide full screening.
• It has the maximum inductance value.
• This inductor provides an appropriate inductance value even for higher values.
• It has maximum permeability with less loss.
• Q factor can be set in a necessary frequency band.

Disadvantages

The disadvantages of ferrite core inductors include the following.

• In ferrite core inductors, the loss will increase at higher frequencies.
• These inductors have complicated isolation.
• They have a more eddy current and also harmonic current rating.

Applications of Ferrite Core Inductor

The applications of ferrite core inductors include the following.

• Ferrite core inductors are mainly used in different electric circuit applications like broadband, power conversion & interference suppression.
• These inductors are utilized in coils that are activated in between an AF to 100 MHZ frequency range.
• These are applicable in power transformers that work from 1 to 200 kHz low-frequency range.
• These are used at both high & medium frequencies.
• These inductors are used in switching circuits, Pi Filters, and also within the ferrite rod antenna which is mainly designed for MW (medium wave) receivers.
• These are used in the power supply or power conditioning components.

Thus, this is an overview of the ferrite core inductor which is a fixed-value inductor. This inductor has a ferrite core arranged within the coil. Other inductors like air core & iron core have less inductance value, more losses & limited frequency operation. So, by using ferrite core inductors these problems can be defeated. So this inductor is the correct choice for different electrical requirements. Here is a question for you, what is the function of an inductor?