Abstract : This paper analyzes the composition, harmonic generation principle, and electromagnetic compatibility (EMC) of frequency converters, and provides measures to minimize the EMC impact of frequency converters, along with relevant engineering examples. Keywords : Frequency converter; Electromagnetic compatibility; Harmonics; Measures; Examples Various electrical equipment used in industrial settings, such as PLCs, CNC equipment, frequency converters, low-voltage electrical appliances, and industrial control instruments, all have their own EMC standards. The International Electrotechnical Commission (IEC) defines EMC as "a function of electronic equipment that enables it to perform its function in an electromagnetic environment without generating intolerable interference." China's recently promulgated national standard for "Electromagnetic Compatibility" defines EMC as "the ability of a device or system to function normally in its electromagnetic environment without causing unacceptable electromagnetic interference to anything in that environment." Clearly, EMC has a dual meaning: anti-interference and interference resistance. Variable frequency speed control has advantages such as simple circuitry, high power factor, smooth starting, and wide speed range, and occupies an extremely important position among various speed control methods for electric motors. Frequency converters mostly operate in harsh electromagnetic environments. As power electronic devices, they are composed of electronic components and microprocessor chips, making them susceptible to external electromagnetic interference. Furthermore, the voltage and current on the input and output sides of frequency converters contain abundant high-order harmonics, becoming sources of interference and interfering with other electronic equipment. [b]1 Frequency Converters and Their Electromagnetic Compatibility 1.1 Working Principle of Frequency Converters[/b] Figure 1 shows the structural block diagram of a voltage source AC-DC-AC frequency converter. As shown in the figure, the main circuit of this frequency converter consists of a rectifier, a DC link, and an inverter. The rectifier converts the input AC power into DC power through power diodes. The DC link consists of a large capacitor, which, in addition to filtering and buffering the reactive power of the load, also keeps the DC voltage of the main circuit stable. The inverter, under the control of the PWM controller, converts the DC power processed by the DC link into a rectangular wave voltage with adjustable frequency and variable width. [b][align=center]For more details, please click: Electromagnetic Compatibility and Suppression of Frequency Converters[/align][/b]