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Mobile WebSiteThe rotation speed of the rotor of the three-phase asynchronous motor is lower than the rotation speed of the rotating magnetic field, and the rotor winding generates electromotive force and current due to the relative motion between the rotor and the magnetic field, and interacts with the magnetic field to generate electromagnetic torque to realize energy conversion.
Compared with single-phase asynchronous motors, three-phase asynchronous motors have good running performance and can save various materials. According to the rotor structure, three-phase asynchronous motors can be divided into two types: cage type and winding type. The asynchronous motor of the cage rotor has simple structure, reliable operation, light weight and low price, and has been widely used. The main disadvantage is that the speed regulation is difficult. The rotor of the wound-type three-phase asynchronous motor is also provided with a three-phase winding like a stator and is connected to an external varistor through a slip ring and a brush. Adjusting the varistor resistance can improve the starting performance of the motor and adjust the speed of the motor. The three-phase asynchronous motor is divided into general-purpose motors, which are suitable for places that are free of flammable, explosive, corrosive gases and relatively clean.
The principle of action of three-phase asynchronous motor
The rotor winding cuts the rotating magnetic field to generate an induced electromotive force, and forms a rotor current in the short-circuited rotor winding, and the rotor current interacts with the rotating magnetic field to generate an electromagnetic force to form a rotational moment. The rotor is rotated at a speed n with the rotating magnetic field and drives the mechanical load. The existence of the difference in rotational speed between the rotor and the rotating magnetic field is a necessary condition for the asynchronous motor, and the rotational speed difference is measured by the slip ratio.
Rotating magnetic field of three-phase asynchronous motor
The rotating magnetic field is a magnetic field whose polarity and size are constant and rotate at a certain rotational speed. The symmetrical three-phase winding flows through a symmetrical three-phase current, producing a circular rotating magnetomotive force and a rotating magnetic field. The three-phase symmetrical winding is the same set of three sets of data. The space (along the inner circle of the stator) is composed of three-phase symmetrical windings with 120° electrical angles. The three-phase symmetrical current can generate a rotating magnetic field.
