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What is an inductor? What role does he have?

Source: Industry News Editor: PingShang Click: Release time: 2021-12-14 08:31:36

What is an inductor? What role does he have?

Inductor is a kind of circuit element, which will generate electromotive force to resist the change of current due to the change of current passing through.

The structure of an inductor is similar to a transformer, but there is only one winding, which is generally composed of a winding, a shield, a packaging material, a skeleton, a magnetic core, or an iron core. When the inductor is in a state where there is no current passing, the circuit will block the current when the circuit is turned on; when the inductor is in the state of current passing, it will maintain the current when the circuit is turned off.

Inductance is the ratio of the magnetic flux of the wire to the current that produces this magnetic flux when alternating current is passed through the wire.

According to Faraday's law of electromagnetic induction-magnetism generates electricity, the changing magnetic field lines will generate an induced electric potential at both ends of the coil. This induced electric potential is equivalent to a "new power source". When a closed loop is formed, this induced electric potential will produce an induced current. It is known from Lenz's law that the total amount of magnetic field lines produced by the induced current is to try to prevent the original magnetic field lines from changing.

Since the original magnetic field line changes originate from the change of the external alternating power supply, from the objective effect, the inductance coil has the characteristic of preventing the current change in the AC circuit. Inductance coils have characteristics similar to inertia in mechanics, and are named "self-induction" in electricity. Sparks usually occur when the knife switch is opened or the knife switch is turned on. This is caused by the high induced electric potential generated by the self-inductance phenomenon.文章配图22

In short, when the inductance coil is connected to the AC power supply, the magnetic lines of force inside the coil will always change with the alternating current, causing the coil to continuously produce electromagnetic induction. This kind of electromotive force generated by the change of the current of the coil itself is called "self-induced electromotive force".

It can be seen that the inductance is only a parameter related to the number of turns, size and shape of the coil and the medium. It is a measure of the inertia of the inductor and has nothing to do with the applied current.

The role of the inductor is mainly to pass DC and block AC, and it mainly plays the role of filtering, oscillation, delay, and trapping in the circuit.

The inductance coil has an obstructive effect on the alternating current, and the size of the obstructive effect is called the inductive reactance XL, and the unit is ohm. Its relationship with inductance L and alternating current frequency f is: XL=2πfL

Inductors can be divided into high-frequency choke coils and low-frequency choke coils.

Tuning and frequency selection: Inductance coils and capacitors can be connected in parallel to form an LC tuning circuit. That is, the natural oscillation frequency f0 of the circuit is equal to the frequency f of the non-AC signal, and the inductance and capacitive reactance of the loop are also equal, so the electromagnetic energy oscillates back and forth between the inductance and the capacitance, which is the resonance phenomenon of the LC loop.

At resonance, the inductive reactance and capacitive reactance of the circuit are equal and reversed. The LC resonant circuit has the function of selecting the frequency and can select the AC signal of a certain frequency f.

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