The difference between synchronous motors, asynchronous motors and DC motors

- Jan 23, 2019 -

What is the difference between synchronous motors, asynchronous motors and DC motors?


DC refers to the power supply that does not pulsate the positive and negative poles; AC refers to the power supply whose direction changes continuously and the current is constantly changing;


  1. The stator of the DC motor is a permanent magnet or an electromagnet. The external DC power source is energized and excited by the rotor brush. The rotor magnetic field is always delayed by the stator magnetic field due to the design angle of the brush, so the rotor is driven.

  2. The synchronous motor stator forms a rotating magnetic field through an alternating current power source; the rotor forms a fixed magnetic field through a direct current power source, and the rotor magnetic field is driven by the rotating magnetic field of the stator;

  3. Asynchronous motors generally only have a stator through an AC power source to form a rotating magnetic field, and the rotor is formed by a conductor to form a "squirrel cage" that is short-circuited at both ends. The rotating magnetic field of the stator cuts the conductor in the squirrel cage to form a current, and then a magnetic field is formed on the rotor and is rotated by the rotating magnetic field of the stator. Since the squirrel cage must have a magnetic field cut with the stator, the rotational speed of the rotor is lower than the rotational magnetic field speed of the stator.

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