Principle of Three-Phase Asynchronous Motor

Three-phase asynchronous motor plays an important role in engineering application because of its simple structure and cheap price. Three-phase asynchronous motor is an induction motor, which corresponds to single-phase asynchronous motor, but single-phase asynchronous motor uses 220V voltage, and three-phase asynchronous motor uses 380V three-phase alternating current, So what is the principle of this three-phase asynchronous motor? Let's look at the basic principle of three-phase asynchronous motor.

Principle of three-phase asynchronous motor

The three-phase winding of the stator of this kind of motor is completed in a space position, and its basic principle is that when the so-called three-phase symmetrical alternating current is applied to the stator winding, a constant speed rotating magnetic field will be established inside the motor. This magnetic field is the selected magnetic field, which is also a comparative condition and the basic basis for the operation of this asynchronous motor.

The generation of this magnetic field is actually the so-called working principle of asynchronous motor. The generation of this rotating magnetic field is actually that there is only one coil for each phase, and there are three such same coils in the motor, which are respectively in the stator core slot. The connection mode of this three-phase asynchronous motor is the star connection mode. Once the power supply of the machine is powered on, the stator winding will also generate symmetrical current.

After entering three-phase symmetrical current in the stator winding, the rotating magnetic field will be generated internally. There is an opposite movement between the rotor and the rotating magnetic field. Because the magnetic line of force is cut, it will generate a certain induction electromotive force. The formation of this electromotive force is mainly determined according to the right hand rule. The rotor winding is closed.

So if the induction motor works, there will be current flowing through the winding. At this time, there will be interaction between the rotor and the rotating magnetic field, and there will be electromagnetic force in the rotor winding. At this time, the direction of other forces is determined by the left-handed rule.

Electromagnetic relationship of three-phase asynchronous motor

In fact, the relationship between three-phase asynchronous motor and electromagnetism is similar to the relationship between motor and transformer we see everyday, because the stator winding of asynchronous motor is actually similar to the winding of transformer every time it is used, and the rotor winding in motor is actually the same effect as the secondary winding of transformer, but it is not a normal winding process, but the winding equivalent to its short circuit.

Of course, there is still a big gap with the transformer, because the transformer is centrally wound on the iron core, while the three-phase asynchronous motor is indeed distributed in the machine on the inner wall of the iron core, and there is a relatively large air gap in the magnetic circuit of the three-phase asynchronous motor.

The method of adjusting the electromagnetic capability of the asynchronous motor is to change the rotor speed, which can make a big change in the electromagnetic torque. So when the equipment has load demand, the three-phase asynchronous motor will achieve its balance. If the equipment load changes, the motor will also be adjusted appropriately. When the load torque decreases, the motor will accelerate, and vice versa.

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