An inductor is a passive electrical component consisting of a coil of wire designed to exploit the relationship between current and electricity generated by the passage of current through the coil. An inductor is a passive component used in most power electronic circuits to store energy in the form of magnetic energy when power is applied. An inductor, also known as an inductor coil, is a passive electronic component that uses the principle of electromagnetic induction to store electrical energy. It usually consists of a coil or spiral conductor, usually wound around an iron or air core. The basic function of an inductor is to produce resistance to changes in current, namely inductive reactance, thereby affecting the characteristics of current flow.
Inductor symbol:
The current i flowing through an inductor produces a magnetic flux proportional to it. However, unlike a capacitor, which opposes changes in voltage across its plates, an inductor opposes the rate of change of current flowing through it due to the accumulation of self-inductive energy in its magnetic field.
How an inductor works:
The working principle of an inductor is based on Faraday's law of electromagnetic induction. When current passes through an inductor, the change in current generates a magnetic field in the inductor's coil. This magnetic field is proportional to the rate of change of the current and generates a reverse electromotive force (EMF) according to Lenz's law to resist the change in current. The generation of this reverse electromotive force allows the inductor to temporarily store electrical energy and respond to changes in current.
Basic parameters of inductors:
Inductance (L): The inductance of an inductor determines its ability to respond to current changes. The unit of inductance is Henry (H). The larger the inductance, the stronger the inductor's resistance to current changes.
Saturation current of an inductor: refers to the maximum current that an inductor can withstand. Beyond this current, the magnetic core of the inductor may saturate, causing the inductance to decrease.
DC resistance (DCR): The coil of an inductor itself has a certain resistance, which affects the performance of the inductor in a DC circuit.
Self-resonant frequency: In some applications, an inductor is combined with a capacitor to form a resonant circuit, and its self-resonant frequency determines the resonant characteristics of the circuit.
Classification of inductors:
Inductors can be divided into several types according to their use and design:
Fixed inductors: Their inductance is fixed and usually used in filtering and impedance matching circuits.
Variable inductors: Their inductance can be adjusted and are suitable for occasions where the inductance needs to be adjusted, such as tuning circuits.
Power inductors: Designed for high current applications, such as power filtering and conversion circuits.
Surface mount inductors: Small surface mount designs suitable for modern electronic devices, with small size and good performance.
Application of inductors:
Inductors are widely used in various electronic and electrical equipment:
Filters: Inductors are often used in power and signal lines to filter high-frequency noise and smooth current.
Transformers: Voltage conversion and signal isolation are achieved through the coupling effect of inductance.
Oscillators: Combined with capacitors to generate signals of specific frequencies.
Energy storage: In switching power supplies, inductors are used to store and release energy to help achieve voltage conversion.
Current sensors: Used to measure current and implement current protection functions.
As a basic component in electronic circuits, inductors resist changes in current through their electromagnetic induction principle and have the functions of energy storage and filtering.
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