[Abstract] This article briefly introduces the interference generated by frequency converters, its causes, propagation paths, and effective suppression methods. [Keywords] Frequency converter, harmonics, anti-interference, electromagnetic compatibility I. Introduction Frequency converters are power electronic devices containing electronic components and computer chips, making them susceptible to external electrical interference. Furthermore, the frequency converter also contains switching components, oscillation circuits, digital circuits, contacts, and switches, all of which generate continuous interference spectra. This means that the operation of a frequency converter must prevent both external interference and interference from the converter itself, commonly referred to as "electromagnetic compatibility" (EMC). To achieve this, corresponding measures and supporting equipment must be taken to ensure the safe, efficient, high-power-factor, and environmentally friendly operation of the frequency converter, thus achieving EMC. II. Causes of Harmonics The output voltage and current generated by the WM control on the output side of the frequency converter contain harmonics. This is because the frequency converter section uses high-speed semiconductor switching elements to generate WM control signals of a certain width and polarity. These pulse signals with steep edges generate strong electromagnetic interference, especially in the output current. They propagate their energy in various ways, interfering with other equipment and severely exceeding the limits of EMC standards. The frequency of harmonics is related to the modulation frequency of the frequency converter. At low modulation frequencies (1kHz-2kHz), the electromagnetic noise (screaming sound) generated by high-order harmonic frequencies is audible to the human ear. If the modulation frequency is high (e.g., 20kHz for IGBT frequency converters), it is inaudible to the human ear, but the high-frequency signal objectively exists. [b][align=center]For more details, please click: Briefly describe the harmonic interference of frequency converters and preventive measures.