Traditional induction motor

First of all, asynchronous motors are induction motors. The principle is that the rotor (usually squirrel-cage rotor, not absolute) "induces" the rotating magnetic field on the stator to make the motor rotate, that is, there must be slip between the rotor speed and the rotating magnetic field of the stator. If there is no sliding, the rotor cannot rotate. Therefore, this kind of motor is also called asynchronous motor.

Secondly, there are many cases where asynchronous motors are used as generators, such as many wind turbines. Because the grid-connected operation condition of asynchronous generator is simpler than synchronous generator, and the structure of the motor itself is also simple, it is often used in generator occasions (the main disadvantage is that reactive power compensation device must be added, but synchronous generator does not need it).

Thirdly, as a motor, its power (whether synchronous or asynchronous) is p = f.v = m.ω ω is angular velocity and m is torque. In the case of constant voltage frequency ratio input, the power of the motor is directly proportional to the rotational speed (or frequency) and angular velocity (regardless of slip), so the torque of the motor can be said to be almost constant.

Fourthly, theoretically, the motor can run at any frequency (if the mechanical strength of the rotor allows, so does the insulation strength of the motor).