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On Common Mode Inductors
May 06, 2018

On Common Mode Inductors

When two inductive coils are close to each other, the change in the magnetic field of one inductive coil will affect the other inductive coil. This effect is mutual inductance. The mutual inductance depends on the inductance of the inductor and the degree of coupling between the two inductors. The component made using this principle is called a transformer. There is a special application of mutual inductance called common mode inductance. Common-mode chokes, also known as common-mode chokes, are wound symmetrically on a closed magnetic ring in the opposite direction and with the same number of turns. The ideal common-mode choke coil has an inhibitory effect on the common-mode interference between L (or N) and E, and there is no inductance-inhibiting effect on the differential mode interference existing between L and N. However, the incomplete symmetry of the actual coil winding will lead to the leakage inductance of the differential mode. When the signal current or the supply current flows in opposite directions in the two windings, the generated magnetic flux cancel each other, and the choke coil exhibits low impedance. Common-mode noise currents (including disturbance currents caused by ground loops, also referred to as longitudinal currents) flow in the same direction across the two windings. The resulting magnetic fluxes add in the same direction, and the choke coils exhibit high impedance, which suppresses common The role of mode noise.

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