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Advantages of magnetic ring type core:
High initial magnetic permeability (this is the basic requirement of common mode inductors), high saturation magnetic induction, stable temperature compared with ferrite (which can be understood as a small temperature rise), and more flexible frequency characteristics, because of high magnetic permeability, it can be small Make a lot of sense and adapt to a wider frequency;
Because the initial magnetic permeability is 5-20 times that of ferrite, the suppression effect on conduction interference is much greater than that of ferrite;
The high saturation magnetic induction of nanocrystalline is better than that of ferrite, so it is not easy to be saturated under high current;
The temperature rise is lower than that of the UF series. Someone actually tested it: it is nearly 10 degrees lower at room temperature (personal test values are for reference only);
The flexible structure makes it adaptable, and it can adapt to different needs by changing the processing technology (I have seen the magnetic ring inductance used in energy-saving lamps, which is quite flexible);
The distributed capacitance will be smaller, because the winding area is wider and the volume is relatively small;
The number of turns used in the ring is less, the distribution parameters are smaller, and the efficiency is superior (for specific analysis, it may be due to the wire diameter, please add);
The hole diameter of the magnetic ring is small, it is difficult for the machine to thread it, and it needs to be wound manually, which is time-consuming, laborious, high processing cost and low efficiency. This is all the more important at a time when cost pressures are increasing.
In terms of pressure resistance, it has little advantage over UF: because you can see that many magnetic rings are separated by cable ties in the middle of the common mode, which is not very reliable. Some of them are separated by a certain distance, and the lines are fixed with glue, which takes a long time , How about the reliability? If the inductance is required to be relatively large, the wires will be crowded together, and there is a little doubt about the safety.
Installation is inconvenient and the failure rate is high.
Because of cost factors, magnetic rings are mostly used in high-power power supplies. Someone described:"Magnetic rings for low power are too high-end", makes sense.
Of course, because of the small size, the magnetic ring is also a very good choice for low-power power supplies that require volume.
Compared with the overall performance, it is better than the UF series. For projects with low cost pressure, magnetic rings can be considered. In an actual test conduction, the margin of the magnetic ring is much lower. And the sensitivity is smaller than that of UF.
Let's talk about the common mode of UF/UU series
Material: basically ferrite, of course, there are differences in ferrite, generally there are MXO-manganese-zinc and NXO-nickel-zinc. The main advantages of nickel-zinc are: the initial permeability is low (less than 1000u), but it can work at a relatively high frequency (greater than 100MHZ), keeping the permeability constant. Very strong and great.
NXO has higher resistivity than MXO. The high-frequency clutter is released in the form of heat by using the similar damping effect of the ferrite on the high-frequency clutter, which explains the temperature problem of the common-mode inductor.
The most important point: the cost is low (the one used by someone is 0.9 yuan), it can be wound by a machine, it is efficient, and UU9.8 or UU10.5 is commonly used;
With a skeleton, the winding process should be better controlled, and higher inductance can be made;
The withstand voltage and reliability are better for the common mode of the magnetic ring;
Good plugin, easy to install. Four pins, there is no problem if the hole position is correct; it is basically used in a small current power supply, because the wire diameter cannot be very thick, so the current cannot be too large;
Space factor: the packaging position is large, maybe because it is stronger, not as small and exquisite as the magnetic ring;
The heat is more serious, and it is also based on my actual measurement: 90V input and full load room temperature can reach as fast as 90 degrees;
It is generally used in occasions with strict cost control or low power;