Synchronous motor and induction motor is a kind of common AC motor. The characteristic is: in steady state operation, there is a constant relationship between rotor speed and power grid frequency, n=ns=60f/p and NS become synchronous speed. If the frequency of the grid is constant, the speed of the synchronous motor is constant at steady state, independent of the magnitude of the load. Synchronous motor is divided into synchronous generator and synchronous motor. The synchronous machine is the main machine in modern power plant.
The establishment of the main magnetic field: the excitation winding through the DC excitation current, the establishment of the polarity of the excitation field between the magnetic field, that is, the establishment of the main magnetic field.
Current carrying conductor: three-phase symmetrical armature winding acts as power winding and becomes the carrier of inductive potential or inductive current.
Cutting motion: the prime mover drags the rotor to rotate (the mechanical energy input to the motor). The exciting magnetic field between the polarities rotates along with the shaft and cuts the stator windings in turn.
The generation of alternating potential: due to the relative cutting motion between armature winding and main magnetic field, the armature winding will induce the three-phase symmetrical alternating potential with the size and direction changed periodically. The AC power supply can be supplied through the lead out line.
Cross degeneration and symmetry: the polarity of the induced potential is alternated due to the polarity of the rotating magnetic field; the symmetry of the armature winding ensures the three-phase symmetry of the induced electromotive force.