Abstract : This paper mainly discusses the application of frequency converters in the production of differential polyester. The use of frequency converters to upgrade existing equipment aims to reduce investment, save time, and thus improve economic efficiency. Keywords : Frequency converter; Polyester; Control 1 Introduction Pursuing product diversification and high added value is the fundamental driving force for enterprise development. Fully tapping the potential of existing equipment to achieve this is undoubtedly advisable. Longdi Group Co., Ltd.'s differential polyester plant can produce nearly 20 different varieties, including bright, semi-dull, cationic, and bottle-grade chips. However, since the industrial filament production began, it was initially rejected because the chip size could not meet the requirements for smooth viscosity enhancement in the solid-phase tower. Should they order another pelletizer (requiring 1 million RMB) or modify the existing equipment themselves? Adhering to the principle of "small investment, big returns," the company decided to solve the problem independently. With the joint efforts of various professionals, after a month, they finally transformed the plant into a pelletizer with adjustable chip size, enabling the plant to produce chips suitable for butadiene industrial filament production, with an investment of less than 20,000 RMB. 2. Hardware Configuration One 18.5kK frequency converter is used to drive the feed shaft, eliminating the original continuously variable mechanical gearbox (the original equipment was a pelletizer manufactured by Rieter in 1986, which suffered from severe mechanical wear and the manufacturer no longer produces spare parts for that model). The control system is now handled by the existing DCS. It is worth mentioning that, to reduce costs and fully utilize the potential of the existing equipment, the pelletizer's cutter is driven by the frequency converter in the polycondensation agitator of the previous process. Because the special process requirements of different polyesters mean that pelletizing can only be carried out when the previous process is stopped, the frequency converter of the polycondensation agitator is idle throughout the pelletizing process, objectively providing the possibility of full utilization. [b][align=center]For details, please click: A Brief Analysis of the Full Utilization of Frequency Converters in Production[/align][/b]