Common Mode Inductor Nanocrystalline Core
Product Features:
Zhili’s common mode inductor core is made of its self-produced 1K107B ultrathin shear strip. This product has good stability, and the initial magnetic permeability can exceed 120,000, even break through 200,000; it also has excellent frequency characteristic, and the magnetic permeability can reach more than 20,000 when the frequency is 100KHz; under the same circumstance as ferrite common mode inductor performance, it can greatly reduce the volume of magnetic core and the copper loss, and has a better cost performance. Meanwhile, our company selects two magnetic core protection and insulation methods for the exterior of common mode inductor core, such as box-packed and coated (see the figure below), in which the coating method can not only realize the beautiful appearance of product but also further reduce the volume of magnetic core and coiling copper loss.
Fig.1 Box-packed Fig.2 Coated
Product application:
It is well known that electromagnetic interference current in the lines can be divided into common mode interference and differential mode interference. The interference current of common mode interference in all wires of cable flows towards the same direction in the return circuit formed between these wires and the “ground”; while the interference current of differential mode interference flows in the return circuit formed between signal lines and “ground” wires. Fig.3 describes this circumstance.
信號源Signal source
噪聲源Noise source
寄生電容Stray capacitance
負載Load
(a) Differential mode noise (b) Common mode noise
Fig.3 Interference current diagram of common mode interference and differential mode interference
Generally the common mode interference is generated by the induction of electromagnetic interference waves from the outside or other parts of circuit in the return circuit between cable and “ground”, and sometimes it is also generated due to the different grounding potential of both ends of cable. This interference is detrimental to the electromagnetic compatibility. On one hand, common mode interference can lead cable to emit strong electromagnetic radiation outwards, thus interfering other parts of circuit or peripheral electronic equipment; on the other hand, in case of the imbalance of circuit, the range and phase of common mode interference in different wires of cable may encounter the discrepancy, at this point, the common mode interference will turn into the differential mode interference, which will seriously influence the quality of normal signal. Therefore, people are always striving to restrain the common mode interference.
Fig.4 shows the basic structure and working principle of common mode choke coil. It is to wind two identical coils on a magnetic core in opposite directions. As shown in fig.4(a), when the differential mode current is flowing through, the magnetic lines of force caused by two coils are in opposite directions and can offset each other, consequently, the magnetic core can’t reach the saturation state under heavy current, and the impedance towards differential mode signal is also very low. This feature is of significance; on the contrary, as shown in fig.4(b), when the common mode current is flowing through, the magnetic lines of force caused by two coils are in the same direction and superposed together, leading to the high impedance towards common mode signal and greatly restraining the common mode interference. In other words, as one common mode choke coil effectively restrains the common mode interference, it has slight effects on useful signals (all the signals are transmitted in differential mode), and furthermore, the curve of its impedance is relatively steep with the increase of frequency. If it is regarded as one low pass filter, its shape factor is a little higher. Therefore, even though the signal frequency and noise frequency are quite close or even in the same band, it can still restrain common mode noise well and have no clear influence on the signal. Besides, it is hard to saturate. These performances are the basic features of common mode choke coil.
相互抵消而不會產生磁場The magnetic forces offset each other and no magnetic field is generated.
電源電壓Power voltage
磁芯Magnetic core
負荷Load
2個繞組的磁場方向一致，會產生磁場The magnetic forces of 2 windings are in the same direction, thus magnetic field will be generated.
電源電壓Power voltage 噪聲Noise
磁芯Magnetic core 負荷Load
(a) Differential mode current situation (b) Common mode current situation
Fig.4 Basic structure of common mode choke coil
Fig.5 Circuit diagram of typical filter of power supply
Fig.6 Common mode filter choke in switching power supply
Compared with ferrite core:
Comparison of performance parameters between nanocrystalline core and ferrite core
|
Performance parameters |
Nanocrystalline core |
Ferrite core |
|
Saturation magnetic induction Bs |
≥1.2 |
0.5 |
|
Initial magnetic permeability μi |
≥120,000 |
≤15,000 |
|
Maximum magnetic permeability μm |
≥800,000 |
≤20,000 |
|
Core loss (W/kg) 0.2/100K |
≤60 |
180 |
|
Curie temperature Tc (℃) |
560 |
150 |
Comparing the shape of Nanocrystalline common mode inductor with that of ferrite common mode inductor (they are of the same filtering effect), it can be found that the Nanocrystalline iron core is less than ferrite in the volume and copper loss.
鐵氧體Ferrite
鐵基納米晶合金Fe-based nanocrystalline alloy
頻率Frequency
Curves of typical performance parameters
Frequency characteristic curve
頻率特性曲線Frequency characteristic curve
初始導磁率Initial magnetic permeability
頻率Frequency
Common specifications and model
|
Specification and model |
Inductance value (single-turn) |
Specification and model |
Inductance value (single-turn) |
|
T OD*ID*H (mm) |
@ 10KHz |
@ 100KHz |
T OD*ID*H (mm) |
@ 10KHz |
@ 100KHz |
|
|
±25% uH |
±25% uH |
|
±25% uH |
±25% uH |
|
T12.7*7.7*7 |
56 |
8.2 |
T27*20*10 |
48 |
7 |
|
T13*9.5*5 |
25 |
3.5 |
T29*20*10 |
60 |
8.2 |
|
T14*10*5 |
27 |
4 |
T30*20*10 |
65 |
9.5 |
|
T14*10*6.5 |
35 |
5.2 |
T40*25*15 |
100 |
15 |
|
T15*10*6 |
39 |
5.6 |
T40*32*15 |
54 |
7.8 |
|
T16*10*5 |
35 |
5.5 |
T50*25*15 |
150 |
18 |
|
T16*11*6.5 |
39 |
5.6 |
T50*32*15 |
95 |
15 |
|
T18*11*8 |
60 |
9.2 |
T50*40*20 |
72 |
10.5 |
|
T20*12*8 |
65 |
9.5 |
T70*50*25 |
115 |
15 |
|
T21*15*8 |
42 |
6.2 |
T80*50*20 |
145 |
20 |
|
T22.5*18*10 |
36 |
5.2 |
T96*80*20 |
55 |
8 |
|
T24*15*15 |
98 |
15 |
T100*60*20 |
150 |
20 |
|
T25*16*10 |
70 |
10 |
T110*80*25 |
120 |
18 |
|
T26*16*10 |
78 |
11 |
T120*70*25 |
200 |
30 |
*can be prepared according to the specifications and performances required by customers
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