Purpose and main parameters of inductance | GETWELL

Functional use of inductors

Inductors are mainly used to filter, oscillate, delay, trap, filter signals, filter noise, stabilize current and suppress electromagnetic wave interference.The most common function of inductance in a circuit is to form an LC filter circuit together with capacitance.Capacitance has the characteristic of "blocking dc and blocking ac", while inductance has the function of "blocking dc and blocking ac".If the direct current with a lot of interference signals is passed through the LC filter circuit, then the ac interference signal will be turned into heat energy consumption by the inductor;When the pure dc current flows through the inductance, the ac interference signal is also changed into the magnetic and thermal energy, and the higher frequency is easily resisted by the inductance impedance, which can suppress the interference signal of higher frequency.

Inductors have the property of preventing ac from passing through and allowing dc to pass through. The higher the frequency, the greater the coil impedance.Therefore, the main function of the inductor is to isolate the ac signal, filter or with capacitors, resistors and other resonant circuit.

The main parameters of the inductance

The main parameters

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

inductance

Inductance, also known as self-inductance, is a physical quantity that represents the inductor's self-inductance.

Inductor inductance size, mainly depends on the coil winding number (turns), winding mode, there is a magnetic core and the core of the material and so on.In general, the more coils and the denser the coil, the greater the inductance.A coil with a magnetic core has a higher inductance than a coil without a magnetic core.The higher the core permeability of the coil, the greater the inductance.

The basic unit of inductance is the Henry, denoted by the letter "H".Also commonly used units are mH and H, and the relationship between them is:

1 h = 1000 mh

Mh 1 = 1000 mu H

Allowable deviation

The allowable deviation refers to the allowable error value between the nominal inductance of the inductor and the actual inductance.

Generally, inductors used in oscillating or filtering circuits require higher accuracy, with allowable deviation of ±0.2%~±0.5%.But for coupling, high frequency choke coil precision requirements are not high;The allowable deviation is ±10%~15%.

Quality factor, also called Q value or excellent value, is the main parameter to measure the quality of inductor.

It refers to the ratio of inductor's inductance to its equivalent loss resistance when the inductor operates at a certain frequency of ac voltage.The higher the Q value of the inductor, the smaller the loss and the higher the efficiency.

The quality factor of inductor is related to dc resistance of coil wire, dielectric loss of coil skeleton, loss caused by iron core and shield.

Distributed capacitance refers to the capacitance between the turns of the coil, between the coil and the magnetic core, between the coil and the earth, 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 and quality factor increase.Reduce the distribution of capacitance commonly used wire or enameled wire, sometimes also used honeycomb winding method.

Rated current

Rated current is the maximum current that the inductor can withstand under permitted operating conditions.If the working current exceeds the rated current, the inductor will change its performance parameters due to heat, or even burn out due to overcurrent