Analysis of the working principle and characteristics of AC asynchronous motor

Why is the AC Asynchronous Motor called an asynchronous motor? Because the speed of the AC asynchronous motor is less than the speed of the rotating magnetic field, it is called an asynchronous motor. It is basically the same as theinduction motor.

AC asynchronous motorsare divided into Induction Motors and AC commutator motors. Induction motors are the most widely used. Induction motors can generally be called asynchronous motors without causing misunderstanding or confusion.

Induction motors are further divided into single-phase asynchronous motors and AC/DC dual-purpose motors

The working principle of the AC asynchronous motor is as follows:

1. When the three-phase asynchronous motor is connected to a three-phase AC power supply, the three-phase stator winding flows through the three-phase symmetrical current to generate a three-phase magnetic motive force and generate a rotating magnetic field.
2. The rotating magnetic field has a relative cutting motion with the rotor conductor. According to the principle of electromagnetic induction, the rotor conductor generates an induced electromotive force and an induced current.
3. According to the law of electromagnetic force, the current-carrying rotor conductor is acted upon by electromagnetic force in the magnetic field, forming an electromagnetic torque, driving the rotor to rotate. When the motor shaft carries a mechanical load, it outputs mechanical energy to the outside.

The characteristics of AC asynchronous motors are as follows:

1. Asynchronous motors are AC motors, and the ratio of their speed under load to the frequency of the connected power grid is not a constant relationship. It changes with the size of the load. The greater the load torque, the lower the rotor speed.
2. The stator winding of an ordinary asynchronous motor is connected to the AC power grid, and the rotor winding does not need to be connected to other power sources. Therefore, it has the advantages of simple structure, convenient manufacturing, use and maintenance, reliable operation, small mass and low cost.
3. Asynchronous motors have higher operating efficiency and better working characteristics. They run at a near constant speed from no-load to full-load, and can meet the transmission requirements of most industrial and agricultural production machinery.
4. Asynchronous motors are easy to generate various protection types to meet the needs of different environmental conditions. When the asynchronous motor is running, it must absorb reactive excitation power from the power grid to deteriorate the power factor of the power grid.
5. The speed of the asynchronous motor has a certain slip relationship with the speed of its rotating magnetic field, and its speed regulation performance is poor. For transportation machinery, rolling mills, large machine tools, printing and dyeing and papermaking machinery that require a wide and smooth speed regulation range, it is more economical and convenient to use DC motors.
6. With the development of high-power electronic devices and AC speed regulation systems, the speed regulation performance and economy of asynchronous motors suitable for wide speed regulation are comparable to those of DC motors.AC asynchronous motors are widely used in household appliances such as electric fans, refrigerators, washing machines, air conditioners, hair dryers, vacuum cleaners, range hoods, dishwashers, electric sewing machines, food processors, and various electric tools and small electromechanical equipment.