AC motors are motors that use the electromagnetic interaction between the stator and the rotor to convert the input AC electrical energy into mechanical energy output. AC motors can be divided into asynchronous motors and synchronous motors according to the relationship between the rotor speed and the rotating magnetic field. At the same time, according to the number of phases powered by the motor during normal operation, they can be divided into single-phase and three-phase AC motors. Similarly, many AC motors also have a reduction mechanism to reduce the speed to the required speed and increase the torque output.

Since three-phase asynchronous motors have good working performance and high cost performance, they are widely used in industrial and agricultural production. In practical applications, there are three speed regulation methods for three-phase asynchronous motors: pole-changing speed regulation, frequency conversion speed regulation, and slip rate change speed regulation. Since frequency conversion speed regulation has superior speed regulation performance, smooth speed regulation, wide speed regulation range, and high efficiency, it has become the most effective speed regulation method with the improvement of the cost performance of frequency converters and the promotion of their application. The change of the running direction of the three-phase asynchronous motor can be achieved by changing the phase sequence of the power supply connected to the AC motor. For motors driven by frequency converters, the speed and direction can be achieved by changing the control parameters of the frequency converter.

AC motors have high working efficiency, no smoke, no odor, no environmental pollution, and low noise. Due to its series of advantages, they are widely used in industrial and agricultural production, transportation, national defense, commercial and household appliances, medical electrical equipment, etc. In particular, most of the fields such as small and medium-sized steel rolling equipment, mining machinery, machine tools, lifting and transportation machinery, blowers, water pumps and agricultural and sideline products processing machinery use three-phase asynchronous motors to drive the machinery.