What Is The Difference Between Common Mode Inductors And Differential Mode Inductors?


First, we need to understand that inductance is a property of a closed loop, that is, when the current through the closed-loop changes, the electromotive force will appear to resist the current change. This inductance is called self-inductance and is a property of the closed loop itself. And today, the common mode inductor and the differential mode inductor brought by the gain inductor are used to resist electromagnetic wave interference, so what is the difference between them?


1. From the naming analysis, the filter inductor to suppress the common mode interference is called the common mode inductor; the filter inductor to suppress the difference - mode interference is called the difference - mode inductor. The disturbance electromagnetic field generates differential mode current between the line and the line, which causes interference on the load. This is differential mode interference. The harassing electromagnetic field generates common mode current between the line and ground, and the common mode current generates differential mode voltage on the load, causing interference, which is the common mode ground loop interference.


2. Line and direction of the difference: common mode inductance is double line bidirectional; the differential mode inductance is unidirectional.


3. Coil difference: common mode inductance is two groups of coils, the two groups of coils around the same core of the same number of turns and wire diameter is the same and wound in the opposite direction;   the differential mode inductor is just a coil around a core.


4. Signal difference: the common mode signal is respectively in the zero line and the live line of two exactly the same signal, the two models are coupling and ground to form a loop;   the differential mode signal is the same loop as the useful signal.


5. Winding difference: common mode has two windings. These two windings are respectively connected to the neutral line and the live line, they are in and out, filtering is the common mode signal;   the differential mode has only one wind and the filter inductors connected to the neutral and live wires can only filter out the differential mode interference.


6. The last is the difference in characteristics: the characteristics of the common mode inductor is: as mentioned above, the common mode inductor is the same core of two groups of coils around the opposite direction, so the core is not afraid of saturation. The most commonly used core materials in the market are high conductance ferrite materials. Differential mode inductors are characterized by their use in high current applications. Because it is a coil wound on a core, when the current flowing into the coil increases, the core in the coil will be saturated, so the most used core material on the market is metal powder core material, but also because of the low price, which is more popular.


Common-mode Inductor
1. Five ring pattern and dimensions( SHAPE AND SIZE) (size: mm)

1. HLFV129




5. UT20

6. WHTBC Series

7. 372215-5mH

8. WHC series common-mode

9. WHTBC series Common-mode

10. HLFD648075 Series

11. UTB16UH:300MH

12. 100UH:1.8H

13. HLFC