Introduction Variable frequency speed control (VFD) is widely recognized both domestically and internationally as the most ideal and promising speed control method due to its excellent speed regulation, starting and braking performance, high efficiency, significant energy saving, and wide range of applications. As a high-tech product, VFDs combine energy saving and environmental protection (two major themes of global economic development) and are receiving increasing attention, gradually replacing DC speed control and playing a crucial role in transmission systems. In recent years, with the continuous improvement of mechatronics technology in textile machinery, AC VFD has become a trend. Almost without exception, most newly developed textile machinery products utilize AC asynchronous motor VFD devices. Many textile factories in China currently possess textile machinery imported from abroad in the 1980s and 1990s, particularly from the United States, Britain, and Japan. At that time, the automation level of such equipment was low. However, new equipment now largely achieves mechatronics and centralized control systems, greatly improving production efficiency and quality, but the equipment cost is quite high. Currently, many industrial control professionals are paying close attention to the automation and VFD retrofitting of textile machinery. This article introduces a recent example of frequency converter technology upgrades for hemp spinning machinery at Dalian Jiamei Carpet Factory, conducted by Dalian Weikete Automation System Co., Ltd. II. Working Principle of Frequency Converter Upgrade for Carpet Machine This carpet machine was manufactured in the United States in the 1980s. Its overall electrical control structure is relatively simple, with a low level of automation. The labor intensity for workers is high. After referring to the working principles and process requirements of modern textile machinery, we carried out a technical upgrade of this equipment. A Danfoss VLT2800 series 15kW frequency converter (with braking resistor) was selected to synchronously control two 5.5kW main shaft motors, using a Siemens LOGO124RC as the core logic controller. Auxiliary detection elements such as Omron photoelectric switches, Schmersal safety pull-cord switches, and German P+K proximity switches are used to control the machine's start-up, stop, alarm, and yarn filling and doffing operations. [b][align=center]For more details, please click: Application of Frequency Converters and PLCs in Textile Machinery Upgrades[/align][/b]