Abstract : This paper mainly introduces the composition, characteristics, and application of the frequency conversion speed control system of the No. 3 continuous casting machine at Taiyuan Iron & Steel Group (TISCO). Based on the ROBIBUS bus-based fully digital drive control strategy, the control of the straightening, stopper bar, large and medium ladle, and various roller conveyors was successfully realized. Keywords: No. 3 continuous casting machine, frequency converter. 1 Overview Compared with traditional continuous casting machines, high-efficiency continuous casting machine technology has developed rapidly in China in recent years due to its advantages of high casting speed, high operating rate, and high quality. The newly built No. 3 continuous casting machine at TISCO is a composite continuous casting machine for square billets and slabs. The computer control system mainly includes square billet, slab, utility systems, flame cutting, marking systems, and electromagnetic stirring systems. The control system uses Siemens S7-300 and S7-400 series programmable controllers. They communicate with each other via industrial Ethernet and ROBIBUS network mode. The HMI operator station is divided into square billet and slab computer monitoring systems. The system also has a data service management center, which communicates via industrial Ethernet. The remote control system adopts an I/O distributed structure and forms a complete control system through the PROFIBUS/USDP communication network. The control systems for the straightening machine, stopper bar, large and medium ladle, and each roller conveyor all use AC variable frequency speed control systems. Considering the process characteristics of each piece of equipment, the high-performance Siemens SIMOVERT MASTERDRIVES 6ES70 vector AC variable frequency drive was selected. 2. SIMOVERT MASTERDRIVES Vector Control Variable Frequency Drive Characteristics With the increasing sophistication of AC variable frequency technology, the application of variable frequency technology in continuous casting machine stopper bars, straightening machines, large and medium ladle, and each roller conveyor has become an inevitable trend. The Siemens SIMOVERT MASTERDRIVES 6ES70 vector control series variable frequency drive has the following advantages: [b][align=center]For more details, please click: Application of AC Variable Frequency Speed ​​Control Technology in Slab and Billet Composite Continuous Casting Machines[/align][/b]