Sünkroonmootorites

Sünkroonmootorites are a type of AC electric motor that operates at a constant speed, determined by the frequency of the AC power supply and the number of poles in the motor. This speed is known as the synchronous speed. Unlike induction motors, where the rotor spins slightly slower than the magnetic field, a synchronous motor's rotor rotates at the exact same speed as the rotating magnetic field in the stator.

The rotor of a synchronous motor can be magnetized in a few ways. One common method is using a DC current supplied to windings on the rotor, creating electromagnets. Another method is employing permanent magnets, particularly in smaller or more specialized designs. The interaction between the stator's rotating magnetic field and the rotor's magnetic field generates torque, causing the rotor to lock into step with the stator field and rotate synchronously.

Synchronous motors are known for their efficiency, especially at full load. They can also be used to improve the power factor of an electrical system by operating with a leading power factor when over-excited. This ability makes them valuable in industrial applications where power factor correction is important.

Starting synchronous motors can be a challenge because at standstill, there is no torque to pull the rotor up to synchronous speed. Various starting methods are employed, including using a smaller induction motor to bring the rotor close to synchronous speed before energizing the rotor field, or using damper windings (similar to those in an induction motor) which allow the motor to start as an induction motor and then synchronize once near speed. Once synchronized, the DC excitation is applied to the rotor.