The disturbing electromagnetic field generates the difference mode current between line and line, which causes interference on the load.
The disturbance electromagnetic field generates the common mode current on-line between the ground, and the common mode current generates
the difference mode voltage on the load, causing interference, which is the common mode ground loop interference
The filter inductors that inhibit common mode interference are called common mode inductors. The filter inductance used to suppress differential
mode interference is called differential mode inductance.
Common mode inductance is two sets of coils with equal winding number, equal wire diameter and opposite direction. Differential mode inductance
is a coil wound around a core.
Common mode inductors are characterized by the fact that the two coils on the same core are wound in opposite directions, so the core is not
afraid of saturation. The most widely used magnetic core material on the market is ferrite material.