Inductors, also known as chokes, reactors, and dynamic reactors. It is an element that can convert electric energy into magnetic energy and store energy in the magnetic field. The structure is similar to the transformer and has the characteristics of DC and AC resistance. In electronic circuits, inductance mainly plays the role of filtering, current limiting, tuning, oscillation, interference suppression and magnetic field generation. Inductance is an attribute of closed loop and a physical quantity. When the current passes through the coil, a magnetic field induction is formed in the coil, and the induced magnetic field will generate induced current to resist the current passing through the coil. It is a circuit parameter that describes the induced electromotive force effect in this coil or in another coil due to the change of coil current. Inductance is the general term of self inductance and mutual inductance. Devices that provide inductance are called inductors. Then, what is the maximum current that the inductor can pass? Strictly speaking, there is no special specification or unified answer standard for the problem of how much current an inductor can generally pass. Why do we say this? It is mainly because the inductance size of different types of inductors is different. Even for the same type of inductor products, there are differences in the current size of different core powder formulas, different winding methods, and different coil turns. Take the Patch inductor as an example, most of the chip inductors have a relatively small current, which is below 1a. It is possible that the current of 2a and 3a is already a large current for the Patch inductor, while the current of the chip integrated inductors can even be more than 20A. This is only the current difference of the same type of inductance, let alone the current difference of different types of inductance.
Inductors mainly play the role of filtering, oscillation, delay, notch, etc. in the circuit, as well as screening signals, filtering noise, stabilizing current and suppressing electromagnetic wave interference. The most common function of inductance in circuit is to form LC filter circuit together with capacitance. The capacitance has the characteristics of DC resistance and AC connection, while the inductance has the functions of DC connection and AC resistance: DC connection: it means that the inductor is closed to DC. If the resistance of the inductance coil is ignored, the DC can pass through the inductor unimpeded. For DC, the resistance of the coil itself is very small, and the blocking effect on DC is very small, so it is often ignored in circuit analysis. AC resistance: when AC passes through the inductive coil, the inductor hinders AC. what hinders AC is the inductive reactance of the inductive coil. Inductance can be made of conductive material coiled around the magnetic core, typically copper wire, or the magnetic core can be removed or replaced with ferromagnetic material. The core material with higher permeability than air can restrict the magnetic field more closely around the inductive element, thus increasing the inductance. The small inductor can be directly etched on the PCB board with a method of laying spiral tracks. Small value inductors can also be used to make transistors. The same process is used in integrated circuits. In these applications, aluminum interconnects are often used as conductive materials. No matter what method is used, based on the actual constraints, the most widely used is a circuit called "spinner", which uses a capacitor and an active element to show the same characteristics as the inductive element. Inductive elements used to isolate high frequencies are often composed of a metal wire passing through a magnetic column or bead. The inductor is generally composed of skeleton, winding, shielding cover, packaging material, magnetic core or iron core, etc. Skeleton generally refers to the support for winding coils. For some fixed inductors or adjustable inductors with large volume (such as oscillation coil, choke ring, etc.), most of them wrap enameled wire (or yarn wrapped wire) around the skeleton, and then install the magnetic core, copper core, iron core, etc. into the inner cavity of the skeleton to improve its inductance. Winding refers to a group of coils with specified functions, which is the basic component of inductor. The winding can be divided into single layer and multi-layer. The magnetic core and magnetic rod are generally made of nickel zinc ferrite (NX Series) or manganese zinc ferrite (MX Series) and other materials, which have "I" shape, column shape, cap shape, "e" shape, tank shape and other shapes.
Inductors, also known as chokes, reactors, and dynamic reactors. It is an element that can convert electric energy into magnetic energy and store energy in the magnetic field. The structure is similar to the transformer and has the characteristics of DC and AC resistance. In electronic circuits, inductance mainly plays the role of filtering, current limiting, tuning, oscillation, interference suppression and magnetic field generation. First, let's talk about the basic principle of inductors, that is, self induction. Self induction: electromagnetic induction phenomenon that occurs when the current flowing through the conductor itself changes. The coil is made of metal wires. When the current flowing through the coil changes, it will produce obvious electromagnetic induction phenomenon. The self induced reverse electromotive force of the coil hinders the change of the current and plays the role of stabilizing the current. Specifically, if the inductor is in the state of no current passing, it will try to prevent the current from flowing through it when the circuit is connected; If the inductor is in a state of current flow, it will try to maintain the current when the circuit is disconnected. From the perspective of energy, the inductor can dump electric energy into magnetic energy and release magnetic energy into electric energy. The same inductor has different blocking effects on current with different changing frequencies. Its general rule is: connect low frequency and block high frequency. The greater the number of coils and the denser the coils are wound, the greater the inductance. The inductance of the coil with magnetic core is larger than that of the coil without magnetic core; The greater the permeability of the core, the greater the inductance of the coil. The basic unit of inductance is Henry, which is represented by the letter H. Common units: milli Heng (MH), micro Heng（ μ H) , nahen (NH). The conversion relationship is: 1h=10^mh=10^6 μ H=10^9nH How to choose the right inductor? The appropriate inductor is mainly determined according to the package size of the inductor, as well as the minimum inductance and rated working current required by the circuit design. In addition, it is also necessary to comprehensively consider the working environment of the inductor, and refer to the working frequency, working voltage and other parameters.
