The influence of the number of differential mode inductors | GETWELL

Does it matter how many differential mode inductors there are? This problem many inductor manufacturers will be confused! So today I will introduce them to you one by one.

What role can differential mode inductors play?

The number of turns of the differential mode inductor must be balanced. If it is not balanced, there must be a problem. The common-mode inductor is a common-mode interference suppression device with ferrite as the magnetic core. it is symmetrically wound on the same ferrite annular core by two coils of the same size and the same number of turns to form a four-terminal device. it has a large inductance for the common-mode signal, but has little effect on the leakage inductance for the differential-mode signal. The principle is that when the common-mode current passes through the magnetic ring, the magnetic flux in the magnetic ring superimposes each other, so that the magnetic flux in the magnetic ring has a considerable inductance, which can restrain the common-mode current; when two common-mode currents pass through the differential-mode current, the magnetic flux in the magnetic ring cancels out each other and there is almost no inductance, so that the differential-mode current will not attenuate when it passes through. Therefore, the common-mode inductor can effectively interfere with the common-mode signal in the balanced line, but has no effect on the differential-mode signal normally transmitted by the line.

The manufacture of differential mode inductors should meet the following requirements:

1. The wires wound on the magnetic core of the coil should be insulated from each other to ensure that the turn-to-turn breakdown or short circuit of the coil does not occur under the action of instantaneous overvoltage.

(4) the coil should be wound into a single layer as much as possible, which can reduce the parasitic capacitance of the coil and enhance the bearing capacity of the coil to instantaneous overvoltage.

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

4) the magnetic core in the coil should be insulated from the coil to prevent both from breakdown under the action of instantaneous overvoltage.

Common mode inductor

Circuit diagram of common mode inductor and differential mode inductor:

The main results are as follows:

1. The interference on the load is called differential mode interference, the common mode current is generated between the electromagnetic field online and the ground, and the common mode current produces differential mode voltage on the load, which is called common mode interference.

2. The filter inductor that suppresses common-mode interference is called common-mode inductor, and the filter inductor that suppresses differential-mode interference is called differential-mode inductor.

3. The common-mode inductor is bi-directional and the differential-mode inductor is unidirectional.

4. The number of coils wound around the same core is equal, the wire diameter is equal, and the two sets of coils with opposite coils are common-mode inductors; differential-mode inductors are coils wound around one core.

5. The common-mode choke is that two windings are connected with zero wire and hot wire respectively, and the two windings go in and out at the same time to filter out the common-mode signal; the differential mode is a kind of filter inductor whose windings are connected to zero wire and hot wire respectively, which can only filter the differential mode interference.

6. Common-mode signal: two identical signals on the zero line and the fire line, respectively, they both couple and form a loop; the differential mode signal is the same loop as the useful signal.

7. Characteristics of common-mode inductors: because two groups of coils on the same core are wound in the opposite direction, the core is not afraid of saturation. The most widely used magnetic core material on the market is highly conductive ferrite.

Differential mode inductors have properties for high current applications. Because the coil is wound around the iron core, when the current flowing into the coil increases, the iron core of the coil will be saturated, so the most commonly used iron core material on the market is metal powder core material. Especially iron powder core materials (because of their low price).

The above is the introduction of the influence of the number of differential mode inductors. If you want to know more about inductors, please feel free to contact us.