Abstract : Starting with the concept of harmonics and combining relevant knowledge of the internal structure of frequency converters, this paper analyzes in detail the causes and hazards of harmonic generation in mining frequency converters. Based on this analysis, common methods for suppressing harmonics are proposed. Keywords : Frequency converter; Harmonics; Suppression 0 Introduction Frequency converter-driven motor systems in mines are increasingly used due to their significant energy-saving effects, convenient adjustment, simple maintenance, and networking capabilities. However, their nonlinear and impulsive power consumption methods have led to significant interference problems. For a single frequency converter, both its input and output terminals generate high-order harmonics. The harmonics at the input terminal can also affect the public power grid through the input power line. 1 What are Harmonics? The fundamental cause of harmonic generation is nonlinear loads. When current flows through a load, its relationship with the applied voltage is not linear, resulting in a non-sinusoidal current, thus generating harmonics. Harmonic frequencies are integer multiples of the fundamental frequency. According to the analysis principle of French mathematician Fourier, any repeating waveform can be decomposed into sinusoidal components containing the fundamental frequency and a series of harmonics that are multiples of the fundamental frequency. Harmonics are sinusoidal waves, each with a different frequency and amplitude. Harmonics can be classified into even and odd harmonics. The 3rd, 5th, and 7th harmonics are odd harmonics, while the 2nd, 4th, 6th, and 8th harmonics are even harmonics. For example, when the fundamental frequency is 50 Hz, the 2nd harmonic is 100 Hz, and the 3rd harmonic is 150 Hz. Generally speaking, odd harmonics cause more and greater harm than even harmonics. In a balanced three-phase system, due to symmetry, even harmonics are eliminated, leaving only odd harmonics. For three-phase rectified loads, the resulting harmonic currents are 6n harmonics, such as 5th, 7th, 11th, 13th, 17th, and 19th harmonics. Frequency converters mainly generate the 5th and 7th harmonics. A schematic diagram illustrating the definition of harmonics is shown in Figure 1. [b][align=center]For more details, please click: Generation and Suppression of Harmonics in Mining Frequency Converters[/align][/b]