The working principle of three phase asynchronous motor, the working principle of three phase asynch

When the three-phase asynchronous motor is connected to the three-phase AC power supply, the three-phase stator winding flows through the three-phase magnetodynamic potential generated by the three-phase symmetrical current and generates a rotating magnetic field, which rotates clockwise along the stator and the inner circular space of the rotor at a synchronous speed. This rotating magnetic field has a relative cutting motion with the rotor conductor, which, according to the principle of electromagnetic induction, generates an induced electromotive force and generates an induced current. According to the law of electromagnetic force, under the action of induced electromotive force, an induced current will be generated in the rotor conductor that is basically the same as the direction of the induced electromotive force.

The current-carrying rotor conductor is subjected to electromagnetic force in the magnetic field generated by the stator, and the electromagnetic force forms an electromagnetic torque on the motor rotor shaft, which drives the motor rotor to rotate along the direction of the rotating magnetic field, and when the motor shaft is loaded with mechanical load, it outputs mechanical energy outward.

When a conductor cuts magnetic field lines within a magnetic field, an induced current is generated within the conductor, hence the name "induction motor". The combined action of the induced current and the magnetic field exerts a driving force on the motor rotor.

We let the closed coil ABCD rotate around the axis XY within the magnetic field B. If the magnetic field is rotated in a clockwise direction, the closed coil is subjected to a variable magnetic flux, which induces an electromotive force that generates an induced current (Faraday's law). According to Lenz's law, the direction of the current is:

The effect of the induced current is always to hinder the cause of the induced current. Thus, each conductor is subjected to the Lorentz force f which is in the opposite direction of motion with respect to the induced magnetic field.

A simple way to determine the direction of each conductive force f is to use the right hand to specify the direction of the magnetic field (magnetic field acting on the current: place the thumb in the direction of the induced magnetic field, and the index finger in the direction of the force. Place the middle finger in the direction of the induced current. In this way, the closed coil is subjected to a certain torque and thus rotates in the same direction as the induced submagnetic field, which is called the rotating magnetic field.

The electric torque generated by the rotation of the closed coil balances the load torque.

The working principle of the three-phase asynchronous motor is based on the interaction of the rotating magnetic field of the stator (the resulting magnetic field generated by the three-phase current in the stator winding) and the rotor current ** the current in the sub-winding).

When the symmetrical three-phase winding of the stator is connected to the three-phase power supply, a symmetrical three-phase current will be passed into the winding, and a rotating magnetic field will be generated in space, and the magnetic field will rotate along the circumferential direction of the stator, when the magnetic field rotates, the conductor cutting magnetic flux of the rotor winding will produce an induced electromotive force e, and due to the presence of electromotive force e, a rotor current i will be generated in the rotor winding.

According to Ampere's law of electromagnetic force, the interaction of the rotor current with the rotating magnetic field will produce an electromagnetic force f (the direction of which is determined by the left-hand rule), which forms an electromagnetic torque on the axis of the rotor, and the direction of the torque is the same as that of the rotating magnetic field, and the rotor is subjected to this torque and rotates in the direction of rotation of the rotating magnetic field.

What is a three-phase asynchronous motor?

Three-phase asynchronous motor is a kind of induction motor, is a kind of motor that is powered by 380V three-phase alternating current (phase difference of 120 degrees) at the same time, because the rotor and stator of the three-phase asynchronous motor rotate in the same direction and at different speeds, there is a slip rate, so it is called a three-phase asynchronous motor.

The stator winding of the three-phase asynchronous motor is a spatially symmetrical three-phase winding, and three symmetrical alternating current currents are introduced into the stator winding, so that a constant-speed rotating magnetic field will be established inside the motor. The direction of the rotating magnetic field is determined by the phase sequence of the three-phase current, that is, the phase sequence of the current entering the three-phase winding can be arbitrarily swapped between two phases, and the direction of the rotating magnetic field can be changed.

Three-phase asynchronous motor is a commonly used AC motor, and its working principle is to use the interaction between the rotating magnetic field generated by the three-phase power supply and the rotor-induced electromotive force to generate torque, thereby driving the motor to rotate.

Specifically, the three-phase current of the three-phase power supply passes through the three-phase coil of the motor in turn, forming a rotating magnetic field. In the rotor of an electric motor, an electromotive force is induced in the rotor conductor due to the action of a rotating magnetic field, resulting in an induced current in the rotor. This induced current creates a magnetic field in the rotor that interacts with the rotating magnetic field to produce torque.

Since the speed of the rotor is lower than the speed of the rotating magnetic field, this torque causes the rotor to start rotating, which in turn drives the load of the motor.

The rotational speed of a three-phase asynchronous motor is related to the frequency of the rotating magnetic field, usually slightly lower than the synchronous rotational speed, which is called "asynchronous". When the load changes, the speed of the motor also changes, but since the frequency of the rotating magnetic field remains the same, the speed of the motor changes less, and the output power is relatively stable.

It should be noted that the three-phase asynchronous motor needs to provide a certain starting torque before starting, otherwise the rotor cannot start and generate a rotating magnetic field. Commonly used starting methods include direct start, self-starting, star angle starting, transformer starting, etc.

Precautions for using three-phase asynchronous motors

1. Power distribution: The use of three-phase asynchronous motors needs to ensure that the power distribution meets the specifications, including voltage, current, frequency and other parameters, so as not to affect the normal operation of the motor.

2. Load matching: When using three-phase asynchronous motors, it is necessary to pay attention to the matching of loads to ensure that the rated power of the motor and the power of the load are matched, so as to avoid overload or underload of the motor.

3. Starting mode: Three-phase asynchronous motor has a variety of starting methods, including direct start, star angle start, auto-coupling step-down start, etc., and it is necessary to choose the appropriate starting mode according to the specific situation.

4. Grounding protection: When using a three-phase asynchronous stool motor, grounding protection measures need to be taken to ensure personal safety.

5. Maintenance: Three-phase asynchronous motors need to be maintained regularly, including cleaning, lubrication, fastening, etc., to ensure the normal operation of the motor and prolong the service life.

The working principle of the three-phase asynchronous motor is based on the principle of electromagnetic induction, when the stator winding passes through the three-symmetrical alternating current, the rotating magnetic field is generated between the stator and the rotor, the rotating magnetic field cuts the rotor winding, and the induced electromotive force and current are generated in the rotor circuit shouting beam, and the current of the rotor conductor is subjected to the action of the rotating magnetic field and makes the friendly rotor rotate. Next, we analyze the generation of the rotating magnetic field, the rotation, slip rate and steering of the Zheng Xuyun motor.

When the three-phase stator winding of the motor (each difference of 120 degrees of electric angle), after the three-phase symmetrical alternating current is introduced, a rotating magnetic field will be generated, which cuts the rotor winding, thereby generating an induced current in the rotor winding** The sub-winding is a closed path), the current-carrying rotor conductor will produce electromagnetic force under the action of the stator rotating magnetic field, so as to form an electromagnetic torque on the motor shaft, drive the motor to rotate, and the motor rotation direction is the same as the direction of the rotating magnetic field.

When a symmetrical three-phase alternating current is passed into the three-phase stator winding, a rotating magnetic field is generated that rotates clockwise along the stator and the inner circular space of the stator at a synchronous speed n1. Since the rotating magnetic field rotates at n1 rotational speed, the rotor conductor is stationary at the beginning, so the rotor conductor will cut the stator rotating magnetic field and generate an induced electromotive force (the direction of the induced electromotive force is determined by the right-hand rule). Since the two ends of the conductor conductor are shorted by the short-circuit ring, under the action of induced electromotive force, the induced current in the rotor conductor will be basically consistent with the direction of the induced electromotive force.

The current-carrying conductor of the rotor is subjected to an electromagnetic force in the stator magnetic field (the direction of the force is determined by the left-hand rule). The electromagnetic force generates an electromagnetic torque on the rotor shaft, which drives the rotor to rotate in the direction of the rotating magnetic field.

Through the above analysis, it can be summarized that the working principle of the motor is: when the three-phase stator winding of the motor (each difference of 120 degrees of electric angle), after the three-phase symmetrical alternating current is introduced, a rotating magnetic field will be generated, and the rotating magnetic field will cut the rotor winding, so as to generate induced current in the rotor winding, and the sub-winding is the base wheel delay closing path), and the current-carrying rotor conductor will generate electromagnetic force under the action of the stator rotating magnetic field, thereby forming an electromagnetic torque on the motor shaft and driving the motor to rotate. And the direction of rotation of the motor is the same as the direction of the rotating magnetic field.

Three-phase asynchronous motor) is a kind of motor that is connected to 380V three-phase AC power supply (phase difference 120 degrees) at the same time, because the rotor and stator of the three-phase asynchronous motor rotate in the same direction and at different speeds, there is a slip rate, so it is called a three-phase asynchronous motor. Three-phase asynchronous motor is an induction motor, after the stator is introduced with current, part of the magnetic flux passes through the short-circuit ring and generates an induced current in it. The current in the short-circuit ring hinders the change of magnetic flux, resulting in a phase difference in the magnetic flux generated by the part with and without the short-circuit ring, resulting in the formation of a rotating magnetic field.

After the power starts, the rotor winding induces electromotive force and current due to the relative motion between it and the magnetic field, that is, the rotating magnetic field has a relative speed with the rotor, and interacts with the magnetic field to generate electromagnetic torque, so that the rotor rotates up and realizes energy conversion.