The origin of asynchronous and synchronous
The AC motor speed is closely related to the armature rotating magnetic field. The rotor speed of the synchronous motor is strictly synchronized with the armature rotating magnetic, and the rotational speed is fixed. The asynchronous motor speed is always lower than the rotating magnetic field speed. The closed loop of the rotor winding induces a current under the action of a rotating magnetic field. In the magnetic field, the rotor current carrying winding is subjected to the continuous action of the magnetic field electromagnetic force, which drives the rotor to rotate, so there are asynchronous and induction motors. Said.
The difference between synchronous motor and asynchronous motor
When the synchronous machine is in steady state operation, there is a constant relationship between the rotor speed and the grid frequency, n=ns=60f/p, where f is the grid frequency, p is the pole pair number of the motor, and ns is called the rotating magnetic field speed or Synchronous speed. The asynchronous motor has a slip rate problem, and the speed is close to the synchronous speed, which is slightly lower than the synchronous speed.
From the perspective of the motor structure, the squirrel-cage rotor or the wound rotor of the asynchronous motor is the same as the stator, and is also a three-phase symmetrical winding. The synchronous motor rotor is excited by the salient pole concentrated winding or the hidden pole distributed winding, and the excitation power source is DC.
2, permanent magnet motor
The permanent magnet motor is divided into two types: permanent magnet DC motor and permanent magnet AC motor.
Permanent magnet DC motors include permanent magnet commutator motors and permanent magnet brushless DC motors or permanent magnet electronic commutator motors. The permanent magnet AC motor is a so-called permanent magnet synchronous motor, which is identical in structure to the permanent magnet brushless DC motor. The driving principle and control method are quite different.
