Abstract : This paper introduces methods for changing the speed of AC motors and the various advantages of variable frequency scroll compressors in terms of energy saving and economy, as well as the application of variable frequency scroll compressors in natural gas compression. It also details the design process of a natural gas variable frequency constant pressure supply system, realizing the application of variable frequency scroll compressors in natural gas compression. The natural gas variable frequency constant pressure supply system possesses the characteristics and advantages of variable frequency scroll compressors, fully meeting design requirements. Keywords : Variable frequency scroll compressor; AC motor; Natural gas; Built-in PID inverter Variable frequency speed control technology for AC motors is a widely used energy-saving technology. Due to the rapid development of electronic technology, the performance of inverters has greatly improved. It can achieve soft start and soft stop of control equipment, which not only reduces equipment failure rate but also significantly reduces power consumption, ensuring safe, stable, and long-term system operation. Previously, compressor systems were entirely manually adjusted to meet gas supply requirements. In various applications, the maximum gas pressure requirement was usually used to determine the corresponding compressor design, and then the motor set was selected based on the gas volume changes, determining the motor's operating mode. Because gas consumption is influenced by various factors, daily gas supply operation control often relies on opening bypass valves. The gas pressure fluctuates with the opening of these valves, resulting in insufficient compressor efficiency and poor economic performance. Another method is to continuously start and stop the compressor, which not only causes instability in the pipeline network but also reduces the machine's lifespan and efficiency. Traditional fixed-speed compressors only have a high energy efficiency ratio under their design conditions; under other conditions, the energy efficiency ratio is relatively low. Variable frequency compressors, on the other hand, can adjust their speed according to different gas volume demands, thus improving the energy efficiency ratio and expanding the range of high energy efficiency. Furthermore, the application of variable frequency speed control technology in compressors successfully solves the major problem of energy consumption. In actual operation, variable frequency constant pressure gas supply technology can achieve fully automatic control, making fully intelligent systems possible. 1. Methods for Changing the Speed ​​of an AC Motor The speed characteristic of an AC motor is: n = 60f(1-s)p, where n is the motor speed, f is the AC frequency, S is the slip, and P is the number of pole pairs. As shown in the formula, the speed can be changed by altering p, s, and f. [b][align=center]For more details, please click: Research and Application of Variable Frequency Scroll Compressors[/align][/b]