Abstract : Based on the actual operation of stacker-reclaimers, this paper briefly introduces the application of frequency converters (VDCs) in various fields, and focuses on the use of the SIEMENS MICROMASTER 440 series VDC in the automatic control system of stacker-reclaimers. Keywords: Frequency converter; Speed ​​regulation; Programmable logic controller (PLC ) 1 Introduction With the development of high-tech industries such as power electronics and automatic control theory, and the increasing maturity of VDC speed regulation technology, VDCs, with their excellent control characteristics, high-efficiency drive performance, and superior energy-saving characteristics, are now widely used in the control of various motors. 2 Application Fields of VDCs VDCs are most widely used for motor speed regulation in various fields. Depending on the different processes of machinery, motor speed regulation is required, which not only saves electricity but also optimizes the process and brings maximum benefits. With the localization of VDC production, the performance-price ratio has significantly improved, so more and more equipment adopts this solution. VDCs are also suitable for fields with certain requirements for speed regulation performance, performing vector control or direct torque control. Furthermore, control function blocks (i.e., accessories) can be added to the VDC itself according to special applications. For applications requiring specific speed control accuracy and range, such as high-speed (above 104 r/min) and extremely wide speed range (1:5 x 104 r/min or wider), specific motors and frequency converters can be used. With the increasing prevalence of wind, hydro, and solar power generation, this type of power generation is receiving more and more attention. For example, solar power generation uses photovoltaic devices to convert solar energy into electrical energy. Since photovoltaic devices generate direct current (DC), a DC-AC inverter must be added to deliver the electrical energy to the power grid or electrical equipment. Frequency converters can also be used as power sources, such as DC-AC inverters, uninterruptible power supplies (UPS), and variable frequency power supplies used in vehicles and ships. [b][align=center]For more details, please click: Application of SIEMENS Frequency Converters in Stacker-Reclaimer Control Systems[/align][/b]