Views: 0 Author: Site Editor Publish Time: 2018-11-17 Origin: Site
An inductor (Inductor) is a component that can convert electrical energy into magnetic energy and has the characteristic of preventing the passage of alternating current and allowing direct current to pass smoothly. The higher the frequency, the larger the impedance of the coil. The inductance of the inductor depends mainly on the number of turns of the coil (number of turns), the winding method, the presence or absence of the core and the material of the core. The inductance is a property of a closed loop, that is, when the current through the closed loop changes, an electromotive force appears to resist the change in current.
The definition of specific inductance:
The inductance is the ratio of the magnetic flux of the wire to the current in which the flux is generated when the alternating current is passed through the wire and the alternating magnetic flux is generated in and around the wire. L=ψ/I
Inductance symbol and unit:
Inductance symbol: L
Inductance units: Hen (H), millihenry (mH), microhenry (uH), Naheng (nH), 1H = 103 mH = 106 uH = 109 nH.
Classification of inductance:
Classified by inductance: fixed inductance, variable inductance.
Classified according to the properties of the magnetizer: air core coil, ferrite coil, iron core coil, copper core coil.
Classified according to the nature of the work: antenna coil, oscillating coil, choke coil, trap coil, deflection yoke.
Classified by winding structure: single layer coil, multilayer coil, honeycomb coil.
Classified by operating frequency: high frequency coil, low frequency coil.
Classified according to structural characteristics: magnetic core coil, variable inductance coil, color code inductor coil, non-magnetic core coil, etc.
The main characteristic parameters of the inductor:
Inductance L: Indicates the inherent characteristics of the coil itself, regardless of the current magnitude. In addition to the special inductor (color code inductor), the inductance is generally not marked on the coil, but marked with a specific name.
Inductive reactance XL: The size of the inductive coil that blocks the AC current is called XL, and the unit is ohm. It is related to the relationship between inductance L and AC frequency f.
Calculation formula: XL=2πfL
Quality factor Q: A physical quantity representing the quality of the coil, and Q is the ratio of the inductive reactance XL to its equivalent resistance, ie: Q = XL / R. The higher the Q value of the coil, the smaller the loss of the loop. The Q value of the coil is related to the DC resistance of the wire, the dielectric loss of the skeleton, the loss caused by the shield or the iron core, and the influence of the high frequency skin effect. The Q value of the coil is usually from several tens to several hundreds. With the magnetic core coil, multiple thick coils can increase the Q value of the coil.
Distributed Capacitance: The capacitance between the turns and turns of the coil, between the coil and the shield, and between the coil and the master is called the distributed capacitance. The presence of the distributed capacitance reduces the Q value of the coil and the stability is deteriorated, so the smaller the distributed capacitance of the coil, the better. The segmented winding method reduces the distributed capacitance.
Allowable error: The percentage of the difference between the actual value of the inductance and the nominal divided by the nominal value.
Nominal current: refers to the current allowed by the coil, usually expressed by the letters A, B, C, D, E, nominal current value is 50mA, 150mA, 300mA, 700mA, 1600mA.
Common inductors:
Single-layer coil: A single-layer coil is wound around a paper tube or bakelite skeleton with a coil of insulated wire. Such as a transistor radio wave antenna coil.
Honeycomb coil: If the coil is wound, its plane is not parallel to the rotating surface, but intersects at a certain angle. This coil is called a honeycomb coil. And the number of times the wire is bent back and forth, often referred to as the number of vertices. The advantage of the honeycomb type winding method is that the volume is small, the distributed capacitance is small, and the inductance is large. The honeycomb coils are wound by the honeycomb winding machine. The more the folding points, the smaller the distributed capacitance.
Ferrite core and iron powder core coil: The inductance of the coil is related to the presence or absence of a magnetic core. Inserting a ferrite core into the air core coil increases the inductance and improves the quality of the coil.
Copper core coil: The copper core coil is used in the ultra-short wave range. The position of the copper core in the coil is used to change the inductance. This adjustment is convenient and durable.
Color code inductor: It is a high frequency inductor coil, which is wrapped with epoxy or plastic after winding some enameled wire on the core. Its operating frequency is 10KHz to 200MHz, and the inductance is generally between 0.1uH and 3300uH. A color code inductor is an inductor with a fixed inductance, and its inductance sign method is marked with a color ring like a resistor. Its unit is uH.
Choke (choke): The coil that restricts the passage of AC power is called the choke, and the high-frequency choke and the low-frequency choke.
Deflection coil: The deflection coil is the load of the output stage of the TV scanning circuit. The deflection coil requires high deflection sensitivity, uniform magnetic field, high Q value, small size and low price.
