How to determine whether a motor is synchronous or asynchronous? I will address this issue in three points.

1. First of all, the main difference between asynchronous motors and synchronous motors is that the speed of asynchronous motors cannot reach the synchronous speed of the stator magnetic field, while synchronous motors can reach the synchronous speed of the stator magnetic field. Their stator windings are the same, but the difference lies in the structure of their rotors. Synchronous motors have a DC excitation winding, while asynchronous motors have a short-circuited winding.

2. Secondly, comparing the two motors, synchronous motors are more complex, have higher manufacturing costs, and require more maintenance work. Currently, synchronous motors are highly efficient under capacitive loads and can improve the power factor of the power grid; whereas asynchronous motors are simple, low-cost, and easy to maintain and install, which is why they are widely used. The downside is that their efficiency is very low, and they have a low power factor, which is not good for the power grid.

3. Another difference is that the speed of synchronous motors during operation is fixed and does not change with variations in load, and synchronous machines are often used as generators. In contrast, the speed of asynchronous motors during operation is not fixed and will change with variations in load.