Structural Characteristics and Operating Principle of Common Mode Inductors

Common mode inductor is an inductive element used to suppress common mode noise in circuits. Common mode noise refers to electromagnetic interference in two power lines (such as power lines or data lines), usually caused by external interference signals or internal circuit faults. In order to improve your understanding of common mode inductors, the following are the working principles and structural features of common mode inductors, hoping to provide you with reference and assistance.

The working principle of a common mode inductor is to counteract common mode noise through the electromagnetic induction effect of the inductor. When common mode noise occurs, it generates current signals of the same size and phase on both power lines of the power supply. These current signals induce a magnetic field in the common mode inductor, resulting in a reverse electromotive force that resists common mode noise. This reverse potential suppresses common mode noise and converts it into electromagnetic energy.

In principle, the suppression effect of a common mode inductor depends on its inductance value, number of turns, and frequency response. Generally, the inductance value of a common mode inductor should be large enough to ensure that sufficient reverse potential is generated in the circuit. In addition, the number of turns of the common mode inductor should be large enough to improve the magnetic field strength and inductance impedance. Finally, the frequency response of the common mode inductor should be sufficiently flat to ensure that common mode noise is suppressed throughout the entire output power range.

The structure of common mode inductors is different from that of ordinary inductors, with some structural features as follows:

Double winding resistance structure: Common mode inductors generally adopt a double winding resistance structure, with one side being a positive power line and the other side being a negative power line. This structure can generate a reverse electromotive force in the circuit to resist common mode noise.

Magnetic core: Magnetic core is commonly used for common mode inductance to enhance magnetic field strength and inductance impedance. The magnetic core generally adopts high permeability materials such as ferrite or nickel zinc ferrite.

Housing: Common-mode inductors typically have housing maintenance to ensure that the inductor components are not affected by the external environment and to prevent magnetic field leakage.

Coil: Copper or aluminum wire is typically used for common mode inductive coils, achieving specific inductance values and turns based on accurate winding and lamination.

Rated voltage: Common-mode inductors typically have a rated voltage, which refers to the maximum current that the inductor component can withstand. The rated voltage depends on the size, wire diameter, and magnetic core material of the inductor component.

The combined effect of these structural characteristics enables common mode inductors to effectively counteract common mode noise in the circuit, thereby ensuring the reliability and stability of the power supply.