There are several classifications of switching power supply EMI transmission channels

There are several classifications of switching power supply EMI transmission channels

 

There are two types of switching power supply EMI transmission channels:

Transmission channel for EMI conducted interference

 

(1) Capacitive coupling

 

(2) Inductive coupling

 

(3) Resistive coupling, including the resistive conduction coupling generated by the internal resistance of the public power supply, the resistive conduction coupling generated by the impedance of the common ground wire, and the resistive conduction coupling generated by the impedance of the public line.

 

Transmission channels for radiated interference

 

(1) In the switching power supply, the components and wires that constitute the source of radiation interference can be assumed to be antennas, so as to use the theory of electric dipoles and magnetic dipoles to analyse. Diodes, capacitors, and switching power tubes can be assumed to be electric dipoles, and the inductor coils can be assumed to be magnetic dipoles.

 

(2) When there is no shield, the electromagnetic wave transmission channel generated by the electric dipole and the magnetic dipole is air (it can be assumed to be free space).

 

(3) When there is a shield, considering the gaps and holes of the shield, and analyze and deal with it according to the mathematical theory and model of the leakage field.