[Abstract] This article introduces the application of frequency converters in the blast furnace probe control system for accurate detection of blast furnace burden surface. [Keywords] Frequency converter, probe, burden surface following. Introduction Due to the simplicity and durability of AC motors, many traditional industrial equipment driven by DC motors adopt AC frequency conversion speed control systems. However, this also increases the difficulty of system control. For example, in the application of blast furnace probes, traditional DC numerical control is generally used, and the application of frequency conversion technology is not widespread because the burden surface following performance is difficult to control, especially for frequency converters without vector control. The No. 4 blast furnace of Xiangtan Iron and Steel Company started production in February 2004. The probe control system adopted AC frequency conversion control without vector control. Through the exploration of technical personnel at all levels, a successful application of AC frequency conversion technology was found. Hardware configuration of the probe system for the No. 4 blast furnace of Xianggang Steel: Frequency converter: Schneider's Altivar58 Communication card: VW3-A58302 Communication method: peercop PLC: Schneider product 140CPU53414 Programming software: Concept2.5 Motor: Variable frequency motor YzPB(F)132M2-65.5KW 380V [b]1 Probe process analysis 1.1 Probe working principle[/b] The probe is a device for detecting the surface of blast furnace materials. It consists of a metal chain connected to a weight (cast iron hammer, cylindrical, 0.22 meters in diameter and 0.75 meters in height) and hung on a mechanism composed of a motor, reducer and sprocket. In order to control its lifting, lowering and positioning, there is also a brake device. The encoder communicates with the PLC through the DP bus. The actual running distance of the probe is calculated by the encoding program in the PLC, thereby obtaining the depth of the probe to the surface of the material. [b][align=center]For details, please click: Application of Variable Frequency Technology in Blast Furnace Gauges[/align][/b]