How does a Common mode inductor help to suppress the noises of Switching power supplies?

Switching power supplies generate common-mode noise in the frequency range of 10 kHz to 50 MHz or higher. To effectively attenuate these noises, common-mode inductors are required to provide sufficiently high inductive immunity in this frequency range. Before explaining the working principle of the common mode inductor, you should understand the structure of the common mode inductor, which helps to understand the common mode inductor suppressing common mode high frequency noise.

The two sets of coils of the common mode inductor are wound around the magnetic ring and wound around the same number of turns in the same direction, except that one set of coils is wound on the left side and the other set of coils is wound on the right side. Common mode inductors use high magnetic permeability MnZn ferrite or amorphous materials to improve common mode inductor performance.


(1) Normal AC current flows through the common mode inductor for analysis. 220 V AC is a differential mode current that flows through a common mode inductor.

(2) Common mode current flows through the common mode inductor analysis. When the common mode current flows through the common mode inductor, the current is common to the common mode current in the common mode inductor, so that the common mode current is more suppressed and the common mode current is attenuated. The effect of the mode interference noise. Any questions, please contact us at sales@xfullstar.com