Abstract : This paper illustrates the application examples of variable frequency speed control in special-purpose equipment from the perspectives of process automation and energy efficiency, explaining its reasonable scope of use. It also introduces the characteristics of AC variable frequency speed control, the determination of inverter capacity, and its rational application in special-purpose equipment. Keywords : Variable frequency speed control; Mechanical speed change; DC speed control; Special-purpose equipment 0 Introduction In the design of special-purpose equipment, various speed control methods are often used to meet the production process requirements of various products. Commonly used methods include mechanical speed change, DC speed control, and AC variable frequency speed control. With the development of large-scale integrated circuits and computer control technology, AC electric drive systems have gradually acquired excellent technical performance such as a wide speed range, high speed stability accuracy, and fast dynamic response, making them comparable to DC electric drive systems in terms of speed control performance. Among AC speed control technologies, variable frequency speed control has an absolute advantage because its speed control performance and reliability are constantly improving, its price is constantly decreasing, and especially its energy-saving effect is significant. Furthermore, it is easy to automate the process, which is unmatched by mechanical speed control. Therefore, it has been widely used in special-purpose equipment. 1. Comparison of AC Variable Frequency Speed ​​Control and DC Speed ​​Control There are three methods for speed control of AC motors: pole changing speed control, slip regulation, and variable frequency speed control. Among them, variable frequency speed control has the greatest advantages. This section compares AC variable frequency speed control systems with DC speed control systems. [b][align=center]For more details, please click: Application of AC Variable Frequency Speed ​​Control Technology in Specialized Equipment[/align][/b]