Basic Principle of Inductance

Inductance as one of the three passive devices, in terms of function, is a kind of electromagnetic induction components, also known as chokes, reactors, dynamic reactors, coils, chokes, etc., its main function is to store electric energy, coil current magnetic field, the magnetic field to generate current, can be converted into magnetic energy storage, so as to ensure voltage stability. There are also functions such as sorting and filtering signals, filtering noise, stabilizing current and suppressing electromagnetic interference (EMI squelch filter). Inductor is an important electronic component, which plays a vital role in circuit design. This article will introduce the basic principles, types, core parameters and selection points of inductors to help you better understand and apply inductors.

When an electric current is passed through the coil, a magnetic field is generated, thereby storing magnetic energy in the coil. The charging and discharging process of the inductor is the process of magnetic field storage and release. The inductance value of the inductance is related to the number of turns of the coil, the area of the coil and the permeability of the surrounding environment. In general, the larger the number of turns of the coil, the larger the area of the coil, the higher the permeability of the surrounding, the greater the inductance value.

The structure of an inductor is similar to that of a transformer, but there is only one winding, and its shape is formed by winding a wire in a circle. It is generally composed of a skeleton, a winding, a shielding cover, a packaging material, a magnetic core or an iron core, etc. When alternating current passes through the wire, alternating magnetic flux is generated inside and around the wire, thus playing the role of "passing DC and resisting AC, it can be seen from Lenz's law that the magnetic lines of force will prevent the change of the original magnetic lines of force. The role of inductance is opposite to that of capacitance. It is often combined with capacitance to form LC filter circuit. If the inductor is in a state where no current is passing through, it will try to prevent current from flowing through it when the circuit is turned on; if the inductor is in a state where current is passing through, it will try to maintain the current when the circuit is turned off. Therefore, it has the functions of filtering, oscillation, delay, notch, etc., as well as the functions of filtering signals, filtering noise, stabilizing current and suppressing electromagnetic wave interference. It and resistors or capacitors can form a high-pass or low-pass filter, phase shift circuit and resonant circuit, etc., is widely used.