Magnetic bead and its working principle
Magnetic beads knowledge
Magnetic bead and its working principle, this paper had a magnetic bead and its principle of work of systemic, this article is about 1020 words, read the full article 10 minutes, the following is the text content.
The main raw material for ferrite magnetic beads, ferrite is a kind of cubic lattice structure of ferrous magnetic materials, ferrite materials for magnesium alloy of iron or iron nickel alloy, its manufacturing process and mechanical properties similar to ceramic, color for a film.
Electromagnetic interference filter is often used in a class of magnetic core is ferrite materials, many manufacturers offer specialized for electromagnetic interference suppression of ferrite materials.
The characteristics of this material is a very big loss at high frequency, high permeability, it can make the inductance of the coil winding in the high frequency under the condition of high resistance between the minimum capacitance.
Ferrite materials usually used in high frequency condition, because of the low frequency when they primarily presents the inductance characteristic, make the loss is very small.
Under the condition of high frequency, they mainly presents the reactance characteristic and change with frequency.
Practical applications, the ferrite material is used as a radio frequency circuit of high frequency attenuator.
In fact, ferrite can better equivalent resistance and inductance in parallel, low frequency resistance are short circuit inductance, inductance under high frequency impedance becomes quite high, so that all current through a resistor.
Ferrite is a consumption device, high frequency energy is converted into heat energy, which is determined by its resistance characteristic.
To suppress electromagnetic interference with ferrite, the most important performance parameter for magnetic permeability and saturation magnetic flux density.
Permeability can be expressed as the plural, real parts inductance, the imaginary part on behalf of the loss, as the frequency increases.
So it's equivalent circuit of inductance L and R series circuit, the resistance R and inductance L is a function of frequency.
When the wire through the ferrite core of inductance impedance is increased with the frequency and increase in form, but in different frequency when the mechanism is completely different.
At high frequencies, impedance is mainly composed of resistance to composition, with the increase of frequency, magnetic core's permeability decreased, leading to the inductance of the inductance, inductance components is reduced, but at this time of the magnetic core loss increases, the resistance components increase, lead to the total impedance increases, when the high frequency signal through the ferrite, electromagnetic interference is absorbed and translated into heat energy in the form of consume.
At low frequencies, the impedance is mainly composed of the inductance of the inductance, the low frequency when R is very small, the core permeability is higher, so the large inductance, inductance L plays a main role, electromagnetic interference is reflected and suppressed, and then the core loss is small, the whole device is a low loss, high quality factor Q characteristics of inductance, the inductance easy to cause resonance, thus may occur when in low frequency interference phenomenon of enhanced after using ferrite beads.
Magnetic bead is a lot of more phyletic, the manufacturer provides technical indicators, especially the relationship between impedance and frequency magnetic beads curve.
Some have multiple holes, magnetic beads with wire through the impedance can increase element (
The number of times square) through the magnetic beads
, but the increase in high frequency noise suppression ability could be more than expected, can use many several series magnetic beads.
It is important to note that the energy of high frequency noise by ferrite magnetic moment and the lattice coupling into heat energy to go out, not the noise import or stop back, as the bypass capacitor.
Therefore, when installing ferrite beads in the circuit, do not need to set the ground for it.
This is prominent advantages of ferrite beads.
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