Abstract : This paper introduces the experimental principles of three different control circuits for open-loop and closed-loop speed regulation of a three-phase asynchronous motor using an MCS-51 series microcontroller-controlled frequency converter. It also presents demonstration experiments showcasing the anti-interference effects of several anti-interference measures. These experiments closely resemble engineering practice and have good teaching effectiveness. Keywords : Microcontroller; Frequency converter; Speed ​​regulation; Anti-interference 1 Introduction In recent years, microcontrollers, PLCs, frequency converters, and other technologies have been widely used in industrial settings. Students majoring in computer science, electronic information, and automatic control have a strong interest in microcomputer control. Existing experimental kits have played an important role in verifying theoretical teaching experiments. However, the capacity of the micro DC motors provided by these kits is too small, resulting in almost no interference. Anti-interference is a crucial aspect of computer control. To enable students to understand the development and application of new technologies and cultivate their innovation and problem-solving abilities, we have developed a teaching experimental device for realizing open-loop and closed-loop speed regulation of an asynchronous motor using a microcontroller and frequency converter. Except for the frequency converter and asynchronous motor, the rest of this teaching experimental device was built by students under the guidance of teachers using their graduation projects. It features low cost, flexible configuration, clear experimental principles, and the ability to demonstrate the effects of anti-interference measures. 2. System Introduction This system uses an 89C52 microcontroller as the core control component, including a frequency converter, a three-phase asynchronous motor, and Hall sensors. The experimental system structure is shown in Figure 1. The microcontroller can control the frequency converter using serial communication, D/A conversion, and PWM to achieve open-loop and closed-loop speed regulation experiments of the three-phase asynchronous motor. One to three experiments can be selected depending on the configured frequency converter. A strong magnet is installed on the motor shaft. Each time the motor rotates, the Hall sensor generates a pulse. The motor speed is measured by measuring the period of this pulse. For the open-loop speed control experiment, the motor speed is only displayed on a 7-segment LED display. For the closed-loop speed control experiment, in addition to displaying the speed, the difference between the set speed and the actual speed must be calculated. Based on the selected control algorithm, the adjustment amount is calculated to make the actual motor speed close to or equal to the set speed. Students can observe the speed adjustment process through the LED display and can intuitively compare the speed control effects of different algorithms and control methods. [b][align=center]For more details, please click: An Exploration of Motor Speed ​​Control Experiments Using Microcontroller Frequency Converters[/align][/b]