Abstract : This paper analyzes the mechanism of electromagnetic interference (EMI) generated by frequency converters, summarizes its propagation modes, and summarizes and compares various anti-interference measures. Keywords : Frequency converter; Electromagnetic interference 1 Introduction Frequency converters are now widely used in industrial and mining enterprises, high-rise building passenger and freight elevators, water supply transmission, energy conservation, and other fields. However, interference problems also arise during their use. The author has encountered various forms of frequency converter interference in his work. The following analysis and classification summarize the generation mechanism and practical cases. 2 Causes of Electromagnetic Interference Electromagnetic interference refers to the interference caused by the electric and magnetic fields generated by motors and electronic devices that affect the normal performance of other devices. This article only discusses the following two causes of electromagnetic field generation: [b]2.1 External interference to the frequency converter 2.1.1 Interference from thyristor converter equipment to the frequency converter[/b] When there is a large-capacity thyristor converter in the power supply network, because it is always conducting for part of the half-cycle of each phase, it is easy to cause a voltage dip in the network, which may damage the rectifier circuit on the input side of the frequency converter due to a large reverse recovery voltage. As shown in Figure 1 [b][align=center]For more details, please click: Analysis and Countermeasures of Electromagnetic Interference Phenomena of Frequency Converters[/align][/b]