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Material advantages and disadvantages of common mode inductors

In Electronic Infomation Category: M | on April 23,2011

First talk about the ring type:

Core material: a nano-crystalline main; wire: This is not to say;

Core benefits:

High initial permeability (this is the basic requirements of common-mode inductance), high saturation magnetic flux density, temperature stability than the ferrite (which can be understood as the temperature rise is small), the frequency characteristics of a more flexible, because the magnetic high very little can make sense of the amount of relatively wide frequency adaptation;

Overall advantages:

Because the initial ferrite permeability is 5-20 times greater than the inhibition of conducted interference ferrite;

Nanocrystals high saturation flux density than ferrite good, so easy in high current saturation;

Temperature is lower than the UF series, I actually test: at room temperature nearly 10 degrees lower (individual test value for reference only);

Structure so that it is adaptable and 74F373D datasheet and flexible, to change from the processing technology can adapt to different needs (met energy-saving lamps on the use of magnetic inductance, using the very flexible)

Distributed capacitance will be smaller, because the wider area of ??the winding volume is relatively small

Ring turns a little less used, smaller distribution parameters, the efficiency of dominant (for detailed analysis, I guess the reason is because the diameter, hope to add);

Overall disadvantage:

Small aperture ring, threading the machine is difficult, need to manually go around, time-consuming, processing costs and 74F373D price and low efficiency. Increasing cost pressures in the same time, this has been particularly important. Advantages compared to UF

little pressure side: I thought to myself, because to see a lot of the middle ring common mode separated using cable ties, so not very reliable, and 74F373D suppliers and some intermediate certain distance, lines dispensing fixed a long time, reliability, how to? If required relatively large inductance, the line will be crowded together, there is little doubt on the safety.

Inconvenience of installation, high failure rate --- from enthusiasts to share: "The general performance is the same, the same diameter ring than UF10.5 sense to do a higher volume, easy to implement. The same as when the test transmission have experienced a sense of volume UF10.5 better, a difference of about 5 DB! ring if the picture is less expensive as older, but not plug-in, failure is relatively large. If the added base is not cheap, expensive than UF10.5 "


Because of cost factors, mostly used in high-power ring power supply, enthusiast described: "a low-power ring is too high with the" is justified.

Of course, because the small size, there are requirements on the size of a small power supply, the use of magnetic ring is also OK choice.

Overall performance compared to better than UF Department. If the pressure is not the cost of the project, consider using magnetic ring. I passed the actual test, with the rings lower margin more. And the sense of a small amount of UF also compared.

Say that UF / UU series of common-mode

Material: essentially ferrite, of course, there are differences between ferrite, and generally have MXO-MZ class and NXO-nickel-zinc type. The main advantage of nickel-zinc type are: initial permeability is low (less than 1000u), but can work at higher frequencies (greater than 100MHZ), to maintain the permeability change. Very very great.

NXO higher resistance than the MXO. Clutter using high-frequency ferrite damping effect similar to the high frequency clutter heat is released, which explains the common mode inductor temperature problem.

Baidu on the principle of common-mode inductance than that I know: two coils around the same core, the turns and phase are the same (reverse wound). Thus, when the normal circuit current flowing through the common mode inductor, the current in the same phase winding inductance coil by the magnetic fields cancel each other the reverse, when the normal signal current is mainly affected by the coil resistance (and a small amount due to leakage being caused by damping); When the coil is flowing through the common mode interference current, will produce a coil increases with the magnetic field to the coil inductance, the coil performance is high impedance, resulting in a strong damping effect, in order to This attenuation of common mode current, to achieve the purpose of filtering.

Overall advantages:

The most important point: low cost (I use that was 0.9 yuan), you can use the machine around, efficient, common UU9.8 or UU10.5;

A skeleton, winding process should be better controlled, they can do a higher inductance;

Magnetic pressure and reliability is better for common mode;

Good plugin, good installation. Four feet Well, no point holes on the issue; basically used in low current power supply, because the diameter can not use very thick, so the current is not too big;

Overall disadvantage:

Space factors: location of a large package, maybe because it is more strong, so small and not ring;

More serious heat, but also according to my measured: 90V input full load at room temperature, can go to almost 90 degrees;


Generally used in more stringent cost control, or a low-power applications.

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