Abstract : The maximum capacity of GTO frequency converters in AC variable frequency drive systems for rolling mills reaches 20MVA, and the maximum capacity of IGBT frequency converter drive systems reaches 8.8MVA. These drive systems, applied to rolling mill drives, enable high-quality production and improved raw material utilization. This paper introduces IGBT and GTO frequency converters and analyzes their technical characteristics. Keywords : Rolling mill; Frequency converter; Analysis 0 Introduction In recent years, with the advancement of power electronics technology represented by IGBTs and GTOs and control technology represented by vector control, 6kV GTOs and 3.3kV IGBTs have entered practical application, resulting in high-capacity AC variable frequency drive systems. These drive systems, applied to rolling mill drives, enable high-quality production and improved raw material utilization. Currently, the maximum capacity of GTO frequency converter drive systems in AC variable frequency drive systems for main rolling mills reaches 20MVA, and that of IGBT frequency converter drive systems reaches 8.8MVA. In auxiliary drives, IGBT frequency converters have also achieved serialization. This article provides an overview and analyzes the technical characteristics of IGBT and GTO frequency converters used in rolling mill drives, ranging from small to large capacity. 1. Power Conversion and Drive Methods The range of motors used in rolling equipment is very wide: from small capacities of a few kW to large capacities of several thousand kW and even 10,000 kW, with speeds also ranging from low to high. Currently, in the medium and small capacity range (less than 2000 kW), 2- and 3-level IGBT frequency converters are mainly used to drive asynchronous motors. In the large capacity range (not exceeding 5000 kW), 3-level IGBT frequency converters are mainly used, driving both synchronous and asynchronous motors. In the large capacity range (greater than 3000 kW to approximately 10,000 kW), 3-level GTO frequency converters are used to drive both synchronous and asynchronous motors. Among these, AC-AC frequency converters are the most prevalent. AC-AC frequency converters have limited output frequencies and are mainly used in the transmission of low-speed, large-capacity equipment. [b][align=center]For details, please click: A Brief Analysis of AC Variable Frequency Drive Systems in Rolling Mills[/align][/b]