Abstract : This paper analyzes and compares the advantages and disadvantages of high-voltage variable frequency speed regulation with other speed regulation methods (such as stator voltage regulation, pole changing speed regulation, and hydraulic coupling speed regulation). It introduces the application of IGBT direct series high-voltage frequency converters in coal mine belt conveyors, achieving wide-range speed regulation and stable and reliable operation. This has significant reference value for the design and application of frequency converters in the coal mining industry. Keywords : High-voltage frequency converter, IGBT direct series, coal mine belt conveyor, master-slave control 1 Introduction The No. 7 well conveyor belt of Datong Coal Mine Group Company's Majiliang Mine is driven by three high-voltage motors. The entire system consists of three 400kW/6kV high-voltage asynchronous motors operating at rated speed, connected in parallel and driven by hydraulic couplings and reducers to reduce and drive the drums. The conveyor belt is the central hub of Datong Majiliang Coal Mine. If the belt conveyor malfunctions, it will cause a complete mine shutdown, affecting production and causing huge economic losses, and potentially leading to serious social impacts. The configuration diagram of the transmission system is shown in Figure 1. [align=center] Figure 1. Configuration diagram of the transmission system [/align] In Figure 1, M1 and M2 are coaxial motors (i.e., two motors simultaneously control one drum), requiring good synchronicity during motor startup. In the original system, due to factors such as the installation location, structure, and speed regulation characteristics of the hydraulic coupler, the building structure where it was installed vibrated violently, failing to meet the requirements for continued use. To address these issues, after analyzing and comparing various speed regulation methods, it was ultimately decided to use the IGBT direct series high-voltage inverter developed by Jialing Electric Manufacturing Co., Ltd. to control the speed of the high-speed motor of the external conveyor belt, replacing the existing hydraulic coupler. [b][align=center]For details, please click: Application of IGBT Direct Series High-Voltage Inverter in Coal Mine Belt Conveyor[/align][/b]