Solutions for EMI Interference Sources Affecting Switching Power Supplies
Solution to EMI interference source on switching power supply interference
Generally speaking, external radiation, lightning strikes, or grid vibrations are the main manifestations of EMI interference sources in switch power supplies, which can interfere with related components such as rectifier diodes, high-frequency transformers, power switching tubes, and other external environmental factors.
Firstly, introduce the transmission channels of radiation interference
(1) In switch mode power supplies, the components and wires that can form radiation interference sources can be assumed to be antennas, and analyzed using electric dipole and magnetic dipole theories; Diodes, capacitors, and power switching devices can be assumed to be electric dipoles, while inductive coils can be assumed to be magnetic dipoles;
(3) When there is a shielding body, consider the gaps and holes of the shielding body, and analyze and process them according to the mathematical model of the leakage field.
Secondly, it is the transmission channel for conducting interference
(1) Capacitive coupling
(2) Inductive coupling
(3) Resistance coupling
a. Resistance conduction coupling caused by internal resistance of public power supply
b. Resistance conduction coupling caused by impedance of public ground wire
c. Resistance conduction coupling caused by impedance of public lines
