The common function of the inductor in the circuit is to form the LC filter circuit together with the capacitor. As we all know, the capacitor has the ability to "block DC, pass AC", while the inductor has the function of "pass DC, block AC. If the direct current accompanied by many interference signals passes through the LC filter circuit (as shown in the figure), the AC interference signal will be consumed by the capacitor into heat energy. When the relatively pure direct current passes through the inductor, the AC interference signal is also changed into magnetic induction and heat energy, and the higher frequency is easily impedance by the inductor, which can suppress the interference signal of higher frequency.
LC filter circuit
The inductance of the power supply part of the circuit board is generally surrounded by a very thick wire coated with a circular magnetic core of various colors. And there are usually several tall filter aluminum electrolytic capacitors nearby, which are composed of the above-mentioned LC filter circuit. In addition, the circuit board also uses a large number of "snake line + patch tantalum capacitor" to form LC circuit, because the snake line on the circuit board up and down, can also be regarded as a small inductor.
The basic functions of inductors also include: filtering, oscillation, delay, notch, etc.
Image statement: "Pass DC, block AC"
Detailed explanation: In electronic circuits, inductive coils act on AC limited current, and can form high-pass or low-pass filters, phase shift circuits and resonant circuits with resistors or capacitors. Transformers can perform AC coupling, voltage transformation, current transformation and impedance transformation.
From the inductive reactance XL = 2πfL, it is known that the larger the inductance L is, the higher the frequency f is, the larger the inductive reactance is. The magnitude of the voltage across the inductor is proportional to the inductance L, and is also proportional to the current change rate △i/△t.
This relationship can also be expressed by the following formula:
The inductance coil is also an energy storage element, which stores electrical energy in the form of magnetic energy, and the stored electrical energy can be expressed by the following formula: WL = 1/2Li2.
It can be seen that the greater the inductance of the coil, the greater the flow, and the more electric energy stored.