common mode inductor
Why is common mode inductance anti EMI? To understand this, we need to start with the structure of the common mode inductance.
Common mode inductance filter circuit, La and Lb are common mode inductance coils. The two coils are wound around the same core, with the same number of turns and phases. So, when the normal current flows through the common-mode inductance in the circuit, the current in the same phase winding inductance coil magnetic field generated in reverse and cancel each other out, as normal signal current is mainly influenced by coil resistance (and a small amount of damping) caused by the leakage inductance of the; When he has the common-mode current flows through the coil, as a result of the common-mode current ecotropic, would produce in the coil magnetic field direction and increase the coil impedance, make coil performance for high impedance, the stronger damping effect, this attenuation common-mode current, achieve the goal of filtering.Answer the interference sources, in fact, the filter circuit end at the other end to be interference devices, La and C1, Lb and C2 form two groups of low pass filter, can make the common mode EMI signal is on the line control on a low level. The circuit can suppress EMI signal from external EMI signal, and can attenuate the EMI signal generated by the circuit itself, which can effectively reduce EMI interference intensity.