Analyzing common electromagnetic compatibility issues from three aspects
Facing the issue of electromagnetic compatibility, we have mentioned it not only once, but also from a new perspective. The issue of electromagnetic compatibility has always been a concern for electronic engineers. Today, we will mainly elaborate on three aspects of electromagnetic compatibility: interference sources, sensitive sources, and coupling paths!
After identifying these three factors, decide which one to remove. As long as one is removed, the issue of electromagnetic compatibility will be solved. For example, when the disturbance source is lightning and the sensitive source is electronic circuits, all we can do is eliminate the coupling path (because we cannot remove the disturbance source, we cannot prevent lightning from occurring in nature).
Coupling of power lines: The most common and fundamental is the coupling of power lines. That is to say, the disturbance source and the sensitive source share a power line, and the energy of the disturbance source is coupled into the sensitive source through the power line.
Coupling of ground wire: The ground wire is the potential reference point of the circuit, so all circuits will converge to the ground wire, providing conditions for the ground wire to become a coupling path.
Near field coupling: There is stray capacitance and mutual inductance between the disturbance source and the sensitive source circuit. This can couple the energy of the disturbance source to the sensitive source.
Electromagnetic wave radiation: When the disturbance source is working, it will generate electromagnetic wave radiation, which may interfere with nearby wireless receiving devices.
Power line coupling (mechanism of conductive coupling)
Suspecting power line coupling: It is possible to observe whether the interference phenomenon has changed by using different power sources for the disturbance source and sensitive source. If different power lines are used for power supply and the interference disappears, it indicates that the power line is a coupling path.
Suspect ground wire coupling: Similarly, disconnect the ground wire from the disturbance source and sensitive source, and observe whether the interference phenomenon has changed.
Space coupling: Adjust the distance between the disturbance source and the sensitive source, observe whether the interference phenomenon has changed. Space coupling is usually related to distance, and the farther the distance, the smaller the coupling amount, especially in the near field. The energy from a harassing source to a sensitive source is closely related to the distance, usually to the square or even the third power of the distance.
