The coupling method of the coupling capacitor is nothing more than acting on the electronic control system through wires, spaces, public lines, etc. The analysis mainly includes the following.

Direct coupling: This is the most direct method of interference intrusion and the most common method in the system. For example, interference signals directly enter the system through wires and cause interference to the system. For this coupling method, filtering and decoupling can be used to effectively suppress the introduction of electromagnetic interference signals.

General impedance coupling: This is also a general coupling method. This usually happens when the currents of two circuits have a common path. There are two types of common impedance coupling: common ground impedance and power supply impedance. To prevent this coupling, the coupling impedance should be close to zero so that there is no common impedance between the interference source and the interfered object.

Capacitive coupling: It is also called electric field coupling or electrostatic coupling. Because of the distributed capacitance [1], it is a coupling method.

Electromagnetic induction coupling: also known as magnetic field coupling. This is a coupling method caused by electromagnetic fields in internal or external space. A common method to prevent this coupling is to shield devices or circuits that are susceptible to interference.

Radiation coupling: The radiation of electromagnetic field can also cause interference coupling, which is irregular interference. This interference is easily transmitted to the system through the power line. In addition, when the signal transmission line is long, they will radiate and receive interference waves, which is called the antenna effect.

Leakage coupling: The so-called leakage coupling is resistance coupling. This interference usually occurs when the insulation is reduced.