What Is Inductive Coupling?

A coil's current changes, and induced electromotive forces are generated in adjacent coils.They are electrically independent of each other, and their mutual influence is connected by a magnetic field.Electronically, it is called magnetic coupling.
Inductive coupling generally refers to magnetic coupling

A coil's current changes, and induced electromotive forces are generated in adjacent coils.They are electrically independent of each other, and their mutual influence is connected by a magnetic field.Electronically, it is called magnetic coupling.

Chinese name

Magnetic coupling

Foreign name

Magnetic coupling

Nature

Electronics nouns

Related principles

Induced electromotive force

Overview of magnetic coupling

When the current i ₁ is applied to the coil 1. A magnetic flux is generated in the coil 1, and at the same time, a part of the magnetic flux passes through the adjacent coil 2, and this part of the magnetic flux is called a mutual induction magnetic flux. There is a magnetic coupling between the two coils. ^[1]

Magnetically coupled electromagnetism

When a charge is stationary, it does not spin, it only generates an electric field and does not generate a magnetic field. Charges spin as they move, creating a ring-shaped magnetic field around them. In a straight wire passing a direct current, the electrons move forward in a line. Due to the effect of the electron spin, there is a circular magnetic field around the wire. If a straight wire passing a direct current is bent into a circle, the annular magnetic field is closed and it appears as a magnetic moment to the outside. The relationship between the direction of the current and the direction of the magnetic poles conforms to the right-hand spiral rule: half-grip in the right hand, the thumb extended, the four fingers except the thumb pointing in the direction of the current, and the thumb pointing in the direction of the N-pole. The electrons move around the nucleus, which can be regarded as a circular wire passing a direct current, and it appears as an atomic magnetic moment to the outside. The relationship between the direction of the electronic movement and the direction of the magnetic pole is in accordance with the left-hand spiral rule: half-grip in the left hand, the thumb extended, the four fingers except the thumb pointing in the direction of the electronic movement, and the thumb pointing in the direction of the N-pole. ^[2]

Magnetic coupling

The two ends of the conductor are connected to the two terminals of the ammeter to form a closed circuit. When the conductor moves to the left or right in the magnetic field and cuts the magnetic field lines, the pointer of the ammeter is deflected, indicating that a current is generated in the circuit. The resulting current is called induced current. We know that the number of magnetic lines passing through an area is called the magnetic flux passing through this area. When the conductor moves to the left or right to cut the magnetic field lines, the area enclosed by the closed circuit changes, so the magnetic flux passing through this area also changes. The cause of the induced current in the conductor can be attributed to the change in the magnetic flux through the closed circuit. It can be seen that as long as the magnetic flux passing through the closed circuit changes, an induced current will be generated in the closed circuit. This is the condition that generates the induced current. Direction of induced current: When the conductor moves to the left or right, the deflection direction of the pointer of the ammeter is different, which indicates that the direction of the induced current is related to the direction of the conductor's movement. If you keep the direction of the conductor's motion unchanged and reverse the two magnetic poles, that is, change the direction of the magnetic field lines, you can see that the direction of the induced current also changes. It can be seen that the direction of the induced current is related to the direction of the conductor's movement and the direction of the magnetic field lines. ^[2]

How exactly does induced current occur?

It is assumed that the magnetic field lines of the uniform magnetic field are perpendicular to the paper surface downward, the conductor is flat on the paper surface, the direction is south and north, and the moving direction is west. (Use the right-hand rule to determine the direction of the induced current as south). When the conductor moves to the west, it can be considered that the charge in the conductor also moves to the west, and the relationship between the direction of the force on the charge in the magnetic field and the direction of the magnetic field and the direction of charge movement can be determined by the left-hand rule The direction of the current should be south. Connect the two ends of the coil to the ammeter to form a closed circuit. When a magnet is inserted or removed from the coil, the pointer of the ammeter is deflected, indicating that an induced current is generated in the circuit. This is because when the magnet is inserted into the coil, the magnetic flux passing through the coil increases, and when the magnet is pulled out from the coil, the magnetic flux passing through the coil decreases. The amount of magnetic flux passing through the coil changes, which causes an induced current. The process of inserting or removing a magnet into a coil can be equivalent to the process of a conductor cutting a magnetic field line. The change in magnetic flux is only the cause of the surface layer that induces the current. The real reason is that the charge in the coil is moved by Lorentz force. ^[2]

Magnetic coupling classification

Can be divided into the following types:

Indirect coupling: There is no direct relationship between the two modules, and the connection between them is completely realized through the control and call of the main module.

Data coupling: When a module accesses another module, it exchanges input and output information with each other through simple data parameters (not control parameters, common data structures or external variables).

Tag coupling: A group of modules pass record information through a parameter table, which is tag coupling. This record is a substructure of a data structure, not a simple variable. In fact, the address of this data structure is passed;

Control coupling: If a module obviously controls the function of selecting another module by transmitting control information such as switches, flags, and names, it is controlling coupling.

Outer coupling: a group of modules access the same global simple variable instead of the same global data structure, and the information of the global variable is not passed through the parameter table, it is called outer coupling.

Public coupling: If a group of modules all access the same common data environment, the coupling between them is called public coupling. The common data environment can be a global data structure, a shared communication area, a public coverage area of memory, and the like.

Content coupling: Content coupling occurs between two modules if:

(1) A module directly accesses the internal data of another module;

(2) One module does not go through the normal entrance to the other module;

(3) the two modules have a part of the program code overlapping (only possible in assembly language);

(4) A module has multiple entries.

The coupling strength depends on the following factors:

(1) a module calls to another module;

(2) the amount of data transferred from one module to another;

(3) how much control one module applies to another module;

(4) The complexity of the interface between modules.

Couplings can be divided into the following types in order from strong to weak:

(1) Content coupling. Content coupling occurs when one module directly modifies or manipulates data of another module, or directly transfers to another module. At this point, the modified module is completely dependent on the module that modified it. This is the highest degree of coupling and the worst.

(2) Public coupling. Commonly, two or more modules refer to a global data item collectively.

(3) Control coupling. A module transmits a signal (such as a switch value, a flag value, etc.) on the interface to control another module, and the action of the module receiving the signal is adjusted according to the signal value, which is called control coupling.

(4) Mark coupling. Passing complex internal data structures between modules via parameters is called tag coupling. Changes in this data structure will cause changes in related modules.

(5) Data coupling. Basic types of data are passed between modules through parameters, called data coupling.

(6) Indirect coupling. When there is no information transmission between modules, it is indirect coupling.

If there must be coupling between modules, try to use data coupling, use less control coupling, limit the scope of public coupling, and resolutely avoid using content coupling.