The working principle of synchronous motors is based on electromagnetic induction and rotating magnetic fields. The following is the basic working principle of synchronous motors：
1.Structure and Composition
The main components of a synchronous motor include:
Stator: The stator is the stationary part of the motor and usually consists of a set of windings. After being electrified, the windings of the stator generate a rotating magnetic field.
Rotor: The rotor is the rotating part of the motor, which can be a permanent magnet or an electrically excited coil. When the rotor is affected by the rotating magnetic field, it will generate a rotation synchronous with the stator magnetic field.
2.Run synchronously.
The rotor will be driven by the rotating magnetic field and rotate at the same speed as the rotating magnetic field. This is the origin of the name "synchronous", which means that the rotation speed of the rotor is completely synchronized with the rotating magnetic field of the stator without slip (different from asynchronous motors). If the rotor is a permanent magnet, it will be directly driven by the rotating magnetic field generated by the stator, making the rotor rotate along with the rotating magnetic field. If the rotor is an electrically excited rotor (excited by direct current), the excitation current on the rotor will generate a magnetic field on the rotor, and the rotor magnetic field and the stator's rotating magnetic field interact to drive the rotor to rotate synchronously.
3.Starting Process
A special point of the synchronous motor is starting. Since the rotor of the synchronous motor has to run at the synchronous speed, it cannot start directly from a stationary state like an asynchronous motor. Common starting methods include:
Asynchronous starting: By using a squirrel - cage rotor or additional devices to make the motor accelerate first like an asynchronous motor, and then switch to synchronous operation after reaching a speed close to the synchronous speed.
External starting device: Through external devices, such as frequency converters, gradually increase the frequency to make the rotor reach the synchronous speed.
4.Application scenarios.
Synchronous motors are often used in situations where precise speed control or high power is required, such as: generators (such as hydro - power generation and wind - power generation); large - scale industrial drives (such as pumps, compressors); devices for precise positioning (such as CNC machine tools).
