Understanding the Effect of Differential Mode Inductor Turns
Time:2022-06-18 Clicks:

Does it matter how many differential mode inductors there are? Many inductor manufacturers will be confused about this problem!

1. What role can differential mode inductors play?

Differential mode inductor turns must be balanced, if it is unbalanced, there must be a problem. The common mode inductor is a common mode interference suppression device with a ferrite core. It consists of two coils of the same size and the same number of turns wound symmetrically on the same ferrite toroidal core to form a four-terminal The device has a suppressing effect on the common-mode signal with a large inductance, but has little effect on the differential-mode signal with a small leakage inductance. The principle is that when the common mode current passes through the magnetic ring, the magnetic fluxes in the magnetic ring are superimposed on each other, so that the magnetic flux in the magnetic ring has a considerable inductance, which can suppress the common mode current; when two common mode currents pass through the differential mode current, The magnetic fluxes in the magnetic ring cancel each other out, and there is almost no inductance, so that the differential mode current does not decay when passing through. Therefore, the common mode inductance can effectively interfere with the signal in the common mode in the balanced line, but has no effect on the differential mode signal normally transmitted by the line.

2. The production of differential mode inductors should meet the following requirements:

1. The wires wound on the core of the coil should be insulated from each other to ensure that there is no breakdown or short circuit between the turns of the coil under the action of an instantaneous overvoltage.

(4) The coil should be wound in a single layer as much as possible, which can reduce the parasitic capacitance of the coil and enhance the coil's ability to withstand transient overvoltage.

2. When the coil flows through a large instantaneous current, the magnetic core should not be saturated.

4) The magnetic core in the coil should be insulated from the coil to prevent the two from breaking down under the action of instantaneous overvoltage.

Common Mode Inductance

3. Circuit diagram of common mode inductor and differential mode inductor:

1. Causes interference on the load, which is differential mode interference; the disturbance electromagnetic field generates a common mode current between the line and the ground, and the common mode current generates differential mode voltage on the load, causing interference, which is common mode interference.

2. The filter inductor that suppresses common mode interference is called common mode inductor; the filter inductor that suppresses differential mode interference is called differential mode inductor.

3. Common mode inductors are bidirectional; differential mode inductors are unidirectional.

4. 3. The number of turns wound on the same core is equal, the diameter of the wire is the same, and the two sets of coils with opposite windings are common mode inductance; differential mode inductance is a coil wound on a core.

5. The common mode choke coil is two windings connected to the neutral wire and the live wire respectively, and the two windings enter and exit at the same time to filter out the common mode signal; the differential mode is a filter inductance whose windings are respectively connected to the neutral wire and the live wire, which can only filter In addition to differential mode interference.

6. Common mode signal: two identical signals on the neutral line and live line respectively, they all form a loop through coupling and grounding; differential mode signal: it is the same loop as the useful signal.

7. 5. Features of common mode inductance: Since the winding directions of the two sets of coils on the same iron core are opposite, the iron core is not afraid of saturation. The most widely used core material on the market is high conductivity ferrite.

Differential mode inductors have properties for high current applications. Because the coil is wound on the iron core, when the current flowing into the coil increases, the iron core of the coil will saturate, so the most commonly used iron core material on the market is the metal powder core material. Especially the iron powder core material (due to its cheap price).

Does it matter how many differential mode inductors there are? The answer is that it definitely has an impact, and it is appropriate!