Abstract : High-order harmonics and noise generated by frequency converters have adverse effects on surrounding equipment. Understanding the influencing factors and their paths, and taking certain measures, can effectively limit high-order harmonics and attenuate noise. Keywords : High-order harmonics; noise; path Frequency converters are widely used in industrial production and household appliances, but their working principle determines that they will affect the surrounding environment, mainly due to high-order harmonics and noise. 1 The Influence of High-Order Harmonics Currently, most frequency converters use PWM control. Because semiconductor switching devices are used in the rectifier and inverter circuits of frequency converters and switch at a relatively high frequency, there will be certain high-order harmonics in their output voltage and output current. The adverse effects of these high-order harmonics on surrounding equipment include: ① causing distortion of the mains power waveform, causing malfunctions in other equipment on the same power supply. ② generating radio interference waves, interfering with radio receiving devices such as radios and televisions. ③ causing noise, vibration, and overheating of motors. To eliminate these adverse effects, the following countermeasures can be taken: series compensation. Connecting a reactor to the input terminal of the frequency converter reduces high-order harmonics and improves the input power factor of the frequency converter. ② Parallel compensation. The harmonic suppression compensation device is connected in parallel with the frequency converter to the power supply. By connecting passive and active filters, the power supply harmonics are reduced. When using a frequency converter to control the speed of a motor, high-order harmonics will cause electromagnetic noise in the motor windings and iron core, resulting in vibration and overheating. The following measures can be taken to reduce motor noise. (1) Use a high-rigidity motor with low magnetic field density, firmly pressed iron core, and cast iron shell. [b][align=center]For details, please click: The impact of frequency converters on the surrounding environment and countermeasures[/align][/b]