Abstract : This paper briefly introduces the interference generated by frequency converters, including the mechanism of interference generation, propagation path, and effective suppression methods. Keywords : Electromagnetic compatibility, harmonic interference suppression, frequency converter 1 Introduction Frequency converters are power electronic devices containing electronic components and computer chips, making them susceptible to external electrical interference. Furthermore, the frequency converter itself contains switching components, oscillation circuits, digital circuits, contacts, and switches, all of which generate continuous interference spectra. This means that when a frequency converter is put into operation, it must prevent external interference while also preventing it from interfering with external interference; this is 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. 2. Mechanism of Harmonic Generation The output voltage and current generated by the PWM control on the output side of the frequency converter contain harmonics. This is because the inverter section of the frequency converter generates a PWM control signal of a certain width and polarity through high-speed semiconductor switching elements. This pulse signal with a steep transition edge generates strong electromagnetic interference, especially in the output current. The current propagates its energy in various ways, interfering with other equipment and severely exceeding the limits of electromagnetic compatibility standards. The frequency of harmonics is related to the modulation frequency of the frequency converter. At low modulation frequencies (1-2kHz), 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., up to 20kHz in 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: Harmonic Interference of Frequency Converters and Prevention Measures[/align][/b]