Abstract : During the high-power diode rectification and high-power transistor inversion process, explosion-proof frequency converters used in mines generate high-order harmonic currents in the input and output circuits, which can interfere with the power supply system, loads, and other nearby electrical equipment. In practical applications, harmonic interference problems with frequency converters are frequently encountered. This article introduces the composition of explosion-proof frequency converters used in mines, their main circuit, the mechanism of harmonic generation, propagation paths, and effective methods for suppressing interference. Keywords : Explosion-proof frequency converter used in mines; harmonic interference; Fourier series; PWM frequency converter 1 Composition of Explosion-proof Frequency Converters used in mines The block diagram of an explosion-proof frequency converter used in mines is shown in Figure 1. The frequency converter consists of two main parts: the main circuit and the control circuit. The composition of the main circuit is shown in Figure 2. The main circuit consists of three components: a rectifier (rectifier module), a filter (filter capacitor), and an inverter (high-power transistor module); the control circuit consists of a microcontroller (or programmable controller), a drive circuit, and an opto-isolation circuit. Inverters can be made from different components, such as high-power MOS transistors for high-frequency inverters, GTO transistors for large-capacity inverters, and IGBT transistors for small and medium-sized inverters. [b]2 Basic Types of Mining Inverters 2.1 PAM Inverters[/b] PAM (Pulse Amplitude Modulation) inverters are a method of output control that changes the amplitude of the voltage source Ud or the current source Id. Therefore, the inverter section only controls the frequency, while the rectifier section controls the output voltage or current. [b][align=center]For more details, please click: Harmonic Interference and Suppression of Explosion-proof Mining Inverters[/align][/b]