Inductors, also known as chokes, reactors, and dynamic reactors. It is an element that can convert electric energy into magnetic energy and store energy in the magnetic field. The structure is similar to the transformer and has the characteristics of DC and AC resistance. In electronic circuits, inductance mainly plays the role of filtering, current limiting, tuning, oscillation, interference suppression and magnetic field generation.

First, let's talk about the basic principle of inductors, that is, self induction.

Self induction: electromagnetic induction phenomenon that occurs when the current flowing through the conductor itself changes. The coil is made of metal wires. When the current flowing through the coil changes, it will produce obvious electromagnetic induction phenomenon. The self induced reverse electromotive force of the coil hinders the change of the current and plays the role of stabilizing the current. Specifically, if the inductor is in the state of no current passing, it will try to prevent the current from flowing through it when the circuit is connected; If the inductor is in a state of current flow, it will try to maintain the current when the circuit is disconnected.

From the perspective of energy, the inductor can dump electric energy into magnetic energy and release magnetic energy into electric energy. The same inductor has different blocking effects on current with different changing frequencies. Its general rule is: connect low frequency and block high frequency.

The greater the number of coils and the denser the coils are wound, the greater the inductance. The inductance of the coil with magnetic core is larger than that of the coil without magnetic core; The greater the permeability of the core, the greater the inductance of the coil. The basic unit of inductance is Henry, which is represented by the letter H. Common units: milli Heng (MH), micro Heng（ μ H) , nahen (NH). The conversion relationship is: 1h=10^mh=10^6 μ H=10^9nH

How to choose the right inductor?

The appropriate inductor is mainly determined according to the package size of the inductor, as well as the minimum inductance and rated working current required by the circuit design. In addition, it is also necessary to comprehensively consider the working environment of the inductor, and refer to the working frequency, working voltage and other parameters.