Six-hole magnetic beads

The role of six-hole magnetic beads: anti-interference, used for EMC certification. The six-hole magnetic bead has very large loss at high frequencies and has a high magnetic permeability, which minimizes the capacitance between the coil windings of the inductor under the condition of high frequency and high resistance. When a current passes through the bead, the ferrite There is almost no impedance to low-frequency currents, while higher-frequency currents will cause greater attenuation. For ferrites to suppress electromagnetic interference, the most important performance parameters are the permeability μ and the saturation magnetic flux density Bs. Its equivalent circuit is an inductor and a resistor in series, and the value of both components is proportional to the length of the magnetic bead. When the wire passes through this ferrite core, the inductive impedance formed increases with the frequency. High-frequency currents are emitted in the form of heat. At low frequencies, the impedance consists of the inductive reactance of the inductor. At low frequencies, R is small, and the magnetic core has a high magnetic permeability. Therefore, the inductance is large, and L plays a major role. The electromagnetic interference is reflected and suppressed, and the loss of the magnetic core is small. The entire device is a low-loss, high-Q inductor. This inductance can easily cause resonance. Therefore, in the low frequency band, the phenomenon of increased interference may occur after using ferrite beads. In the high frequency range, the impedance is composed of resistance components. As the frequency increases, the magnetic permeability of the core decreases, resulting in a decrease in the inductance of the inductor. The total impedance increases. When high-frequency signals pass through the ferrite, electromagnetic interference is absorbed and converted into thermal energy and dissipated.