The difference between a synchronous and asynchronous wind turbine motor
The most important points of difference between a synchronous motor and an asynchronous motor are:
- The rotor of a synchronous motor consists of a permanent magnet powered by direct current, and the rotor of an asynchronous motor is a cylinder made of ferromagnetic material fixed to the stator by bearings. It has a winding made of short-circuited conductors traversed by currents induced by the magnetic field created by the stator currents, which thus form a rotating magnetic field in the stator.
This is the main difference with a synchronous machine, which has a rotor with a magnetic field from permanent magnets or coils powered by direct current.
- The rotational speed of a motor's shaft is equal to the speed of the rotating field (no slip), and for an asynchronous motor, the slip is not zero.
- The synchronous motor can act as a reactive power compensator.
- When loaded, the asynchronous motor absorbs current higher than the nominal current, and the synchronous motor stalls when the torque exceeds a certain limit.
At startup, the synchronous motor requires a "continuous voltage detection for a wind turbine generator" starting system.
The asynchronous motor is the most used in the industry (manufacturing cost, maintenance, speed variation, etc.).
