[Abstract] This paper elucidates the importance of variable frequency technology (VFD) applications in China. Through a comparison of several energy-saving methods for motors and considering the actual usage of large motors, it discusses the feasibility, necessity, and widespread application value of using VFD technology to retrofit motors. [Keywords] VFD retrofit, benefit analysis I. Introduction In the past decade, with the rapid development of power electronics, computer technology, and automatic control technology, electrical drive technology has faced a historical revolution: AC speed regulation replacing DC speed regulation and computer digital control technology replacing analog control technology have become development trends. AC variable frequency speed regulation technology for motors is a major means of saving electricity, improving process flow to enhance product quality, improving the environment, and promoting technological progress. VFD speed regulation, with its excellent speed regulation and starting/braking performance, high efficiency, high power factor, energy-saving effect, wide applicability, and many other advantages, is recognized both domestically and internationally as the most promising speed regulation method. For many years, the State Economic and Trade Commission, together with relevant departments, has been committed to the development and promotion of variable frequency drive (VFD) technology. It has provided key support in technology development and upgrading, organized evaluation and recommendation work for VFD technology, and made its promotion and application a key investment direction for energy-saving technological upgrading projects for fans and pumps. At the same time, it has encouraged enterprises to focus on development, demonstration projects, and widespread application. According to incomplete statistics, from 1995 to 1997, my country invested 350 million yuan in VFD technology upgrading for fans and pumps, with a total upgraded capacity of 1 million KW, saving 700 million KW×h of electricity annually, and an average investment payback period of about 2 years. In recent years, VFD technology has been widely applied, and the State Economic and Trade Commission has included it in the list of general energy-saving technologies for promotion. The following mainly focuses on the necessity and feasibility of VFD retrofitting of large industrial frequency motors in different fields, thereby promoting the further application of VFD technology throughout society. II. Current Status of Motor Usage Motors are key high-power equipment in factories and mines, and their power consumption accounts for a large proportion of the overall operating costs. Therefore, how to reasonably reduce motor power consumption has become a routine task for many enterprises. With the widespread use of low-voltage frequency converters, their excellent energy-saving effect has been widely recognized by users. However, due to the limited power of motors, although the energy-saving rate is high, the amount of electricity saved is negligible compared to the total energy consumption of the power plant. Therefore, if large motors can be retrofitted for energy conservation, the overall self-consumption rate of the enterprise will be significantly reduced. There are various forms of motor energy conservation, and their energy-saving effects vary considerably. The following will compare and analyze the energy-saving effects of several different energy-saving methods commonly used in fans. III. Comparison of Several Energy-Saving Methods When fans are running, the flow rate required for production will change with production needs, so the fan flow rate must be adjusted. This can usually be achieved by changing the fan pressure-flow curve or the pipeline characteristic curve, thereby changing the operating point and thus the flow rate.