1. Optimization of core material selection
Core material is a key factor affecting the high-frequency filtering performance of common mode series inductors. Traditional ferrite cores perform well in low frequency bands, but their performance decreases at high frequencies due to increased hysteresis loss and eddy current loss. In order to improve high-frequency filtering performance, core materials with excellent high-frequency characteristics, such as nanocrystalline cores, can be selected. Nanocrystalline cores have the characteristics of high permeability and low loss. They can more effectively concentrate the magnetic field in high frequency bands and enhance the inductance of inductors to common-mode signals. Its unique microstructure reduces the movement resistance of the magnetic domain wall and reduces hysteresis loss. At the same time, by properly adjusting the formula and preparation process of the core, its high-frequency magnetic properties can be further optimized, so that common mode series inductors can filter out common-mode noise more accurately at high frequencies and ensure the stable operation of electronic equipment.
2. Improvement of winding method and winding structure
The winding method and winding structure have an important influence on the high-frequency performance of common mode series inductors. When multi-layer winding is used, the interlayer capacitance will form a low-impedance path at high frequencies, weakening the filtering effect of the inductor. Therefore, single-layer winding or special winding layout can be used to reduce the interlayer capacitance. For example, the use of honeycomb winding method can reduce the distributed capacitance between windings and reduce the bypass effect of capacitance on high-frequency signals. In terms of winding structure, a segmented winding can be designed to divide a winding into several sections and connect them in series or in parallel appropriately, change the self-inductance and mutual inductance of the winding, and optimize the high-frequency impedance characteristics of the inductor. In addition, select wires with appropriate wire diameters, and minimize the resistance of the wires while meeting the current carrying requirements, reduce the ohmic loss at high frequencies, and thus improve the filtering efficiency of the inductor in the high-frequency band.
3. Effective application of shielding measures
The electromagnetic environment in the high-frequency band is complex, and common mode series inductors are susceptible to external interference, and they may also radiate interference signals outward. Shielding measures can effectively improve their filtering performance. The inductor can be wrapped with a metal shielding cover. After the shielding cover is grounded, it can block external high-frequency electromagnetic interference from entering the inductor and prevent it from affecting the normal operation of the inductor. At the same time, it can also reduce the leakage of the magnetic field generated by the inductor itself to avoid interference with other circuit components. For the material selection of the shielding cover, metals with high magnetic permeability such as Permalloy can be selected, which can better guide and shield the magnetic field. In addition, in the design of the shielding cover, attention should be paid to the treatment of openings and gaps to minimize the damage to the shielding effect and ensure that the common mode series inductors work in a relatively "pure" electromagnetic environment in the high frequency band.
4. Cooperation with other filtering components
It is difficult to achieve the best filtering effect in the high frequency band by relying solely on common mode series inductors. Cooperation with other filtering components is an important way to improve performance. For example, parallel capacitors in the circuit can form an LC filter circuit. The capacitor presents low impedance at high frequencies, which can complement the high impedance characteristics of the inductor and filter common mode signals of different frequencies more comprehensively. Select capacitors with appropriate capacitance and type. For example, ceramic capacitors have the advantages of good high frequency characteristics and low loss. When combined with common mode series inductors, they can effectively suppress high frequency common mode noise. In addition, resistors can be added to form an LCR filter network. The resistors can act as dampers to suppress possible resonance in the circuit, making the entire filter circuit more stable and reliable in the high frequency band, and further improving the filtering performance of common mode series inductors in high frequency environments.
