In practical applications, AC motors are always connected to production machinery, forming an electric drive system. Different production machinery requires different speeds, and even the same production machinery needs different speeds under different operating conditions. Therefore, it is necessary to adjust the operating speed of the traction system, resulting in AC motor speed regulation. AC motors, especially cage induction motors, have simple structure, reliable operation, convenient maintenance, low cost, and good energy-saving effects due to the lack of mechanical reversing devices, Compared to DC motors in terms of single machine capacity and speed limit; Especially in harsh environments with dust and explosion hazards, AC motors are more suitable. However, the speed regulation performance of AC motors is not as good as that of DC motors, and for a long period of time, AC motors can only operate at constant speed. Solving the speed regulation problem of AC motors has always been a topic of concern and research for electric traction workers. As early as the 1930s, many scholars proposed various AC speed control systems in an attempt to improve the speed control performance of AC motors.