Industrial motors generally refer to motors used in factories, mines, ports, railways, ships, machinery and other industries.Industrial motors are the heart of industrial equipment and occupy an important position in modern industrial production, mainly using various types of motors as core components.Asynchronous motors, commonly known as "induction motors", are based on the principle of adding a reactive element between the phase line and the neutral line of the power supply to balance the electromagnetic torque generated, so they are also called balanced motors. Asynchronous motors are widely used in industrial production because of their simple structure and reliable operation.The asynchronous motor has the advantages of small size and high efficiency because the stator magnetic field is composed of two parts, which generate a rotating magnetic field and an induced magnetic field respectively. Asynchronous motors are usually used in industrial applications where low-speed dragging is infrequent and power is small. Because of its simple structure and low cost, it is widely used. 1. In a rotating magnetic fieldAfter the three-phase stator current is synthesized, a rotating magnetic field is formed. According to the principle of electromagnetic induction, an induced electromotive force will be generated in the rotor winding. The rotor winding is composed of two sets of three-phase symmetrical windings connected in series. If the stator winding is energized, an induced electromotive force will be generated in the rotor, and after excitation, an induced current will be generated. A rotating magnetic field is generated in the induced current. When the power supply frequency is the same, the magnetic field formed by the synthesis of the three-phase stator current rotates synchronously. If the power supply frequency is different, the induced current generated in the rotor winding rotates asynchronously.The asynchronous motor adopts a special structure so that it can work at any speed and is suitable for most production environments. Its biggest features are small size, light weight, high power factor, long life, low-speed high-torque operation, and stepless speed regulation, so asynchronous motors are widely used.2. In the induced magnetic fieldThe synchronous motor uses the periodic change of alternating current to induce a periodic rotating magnetic field in the magnetic field, and cuts the stator coil to generate an induced electromotive force, so that the rotor is induced to rotate to achieve the purpose of the motor.When the synchronous motor is running, the number of rotor poles is always kept constant, and the periodic electromotive force is generated through the armature winding when the rotor rotates. Therefore, the electromotive force compensation link is set in the rotor, that is, by adjusting the current in the winding, It generates an electromagnetic force that is synchronous with the rotation of the rotor.Advantages of synchronous motor: high efficiency and small volume; brushless structure can reduce motor failure; due to the problem of magnetic circuit saturation, the rotor is easily magnetized (saturation effect), so the synchronous motor has a certain power factor (at rated power ), and the speed can be controlled by frequency conversion; good starting performance; low noise; easy maintenance.3. In the stationary stator magnetic fieldA rotating magnetic field can be generated, called a rotating magnetic field; or an induced electromotive force can be generated by a rotating magnetic field, called an induced electromotive force. Asynchronous motors can generate a continuously rotating magnetic field or an induced electromotive force. The frequency of the induced electromotive force is proportional to the rotational speed of the motor, and the torque is proportional to the fourth power of the rotational speed. Therefore, asynchronous motors are usually used in high-speed, high-power, high-torque and low-speed applications.Synchronous motor is an important motor that converts electrical energy into mechanical energy, and is mainly used for rotating machinery. Compared with asynchronous motors, it has many advantages:1. The synchronous motor has a large starting torque under no-load condition, the starting torque is 5~8 times of the rated torque, and the starting time is short.2. Simple structure and low cost;3. Suitable for frequent starting and forward and reverse occasions;4. The torque and speed change with the load, so the speed regulation performance is good;5. It has the characteristics of strong overload capacity.DC motors are mainly used in some special occasions, such as frequent starting or frequent braking. However, due to its complex structure and high manufacturing cost, it is rarely used in industrial production.
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