What are the basic parameters of inductance？

The main parameters

The main parameters of inductance include inductance, allowable deviation, quality factor, distributed capacitance and rated current.

Inductance

Inductance is also called self-inductance, which is a physical quantity that represents the self-inductance of an inductor.

The inductance of an inductor mainly depends on the number of turns (number of turns) of the coil, the winding method, the presence or absence of the magnetic core and the material of the magnetic core, etc. Generally, the more the coil turns and the denser the coil, the greater the inductance. A coil with a magnetic core has a greater inductance than a coil without a magnetic core; the greater the permeability of the core, the greater the inductance.

The basic unit of inductance is Henry (Henry for short), represented by the letter "H". Commonly used units are millihenry (mH) and microhenry (μH). The relationship between them is:

1H=1000mH

1mH=1000μH

Allowable deviation

Allowable deviation refers to the allowable error value between the nominal inductance on the inductor and the actual inductance.

Generally, inductors used in circuits such as oscillation or filtering require high accuracy, with an allowable deviation of ±0.2%~±0.5%; while the accuracy requirements of coils used for coupling and high-frequency blocking are not high; the allowable deviation is ±10 %~15%.

Quality factor is also called Q value or figure of merit, which is the main parameter to measure the quality of inductors.

It refers to the ratio of the inductive reactance presented by the inductor to its equivalent loss resistance when it works under a certain frequency of AC voltage. The higher the Q value of an inductor, the smaller its loss and the higher its efficiency.

The quality factor of an inductor is related to the DC resistance of the coil wire, the dielectric loss of the coil frame, and the loss caused by the core and shield.

Distributed capacitance refers to the capacitance that exists between the turns of the coil, between the coil and the magnetic core, between the coil and the ground, and between the coil and the metal. The smaller the distributed capacitance of the inductor, the better its stability. The distributed capacitance can make the equivalent energy dissipation resistance larger and the quality factor larger. To reduce distributed capacitance, silk-covered wire or multi-strand enameled wire is often used, and sometimes honeycomb winding method is also used.

Rated current

The rated current refers to the maximum current value that the inductor can withstand under the allowable working environment. If the operating current exceeds the rated current, the inductor will change its performance parameters due to heat, and even burn out due to overcurrent.

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