What are the working principles of three-phase asynchronous motors?

The three-phase asynchronous motor is mainly composed of stator, rotor, end cover and other accessories. The stator is mainly composed of stator core, stator winding and frame. The stator core is part of the magnetic circuit of the motor and is mainly used for magnetic conduction. It is required to be made of ferromagnetic materials with good magnetic conduction and low eddy current loss. Generally, it is made of laminated silicon steel sheets with a thickness of 0.5mm. Its inner circle is punched with evenly distributed notches, and the plates are insulated from each other to reduce current loss. The three-phase stator windings are embedded in the slots. The stator windings generate a rotating magnetic field. The stator winding is mostly made of high-strength enameled wire or copper or aluminum wire with insulated outer layer.

The rotor is the rotating part of the motor. It obtains a certain torque and rotates under the action of the rotating magnetic field of the stator winding, thereby driving the mechanical load to work. It consists of rotor core, rotor winding and shaft. The rotor core is also a part of the magnetic circuit of the motor, and it has a certain gap (called air gap) with the stator core. The rotor core is the same as the stator core, which is also made of silicon steel sheets with a thickness of 0.5mm on the outer circle.

The filling sheets are coated with insulating varnish and laminated, and the rotor winding is embedded in the slot. The rotor winding is divided into cage type and winding type according to different structural forms. The cage-type rotor winding is embedded in the rotor slot with copper strips, and short-circuited with copper at both ends, like a cage shape, so it is called a cage-type asynchronous motor. Small and medium-capacity cage-type asynchronous motors mostly use cast aluminum rotors, and larger-capacity motors use double-cage or deep-slot rotors. The wound rotor winding is similar to the stator winding. It is connected into a three-phase winding with high-strength enameled wire according to certain rules, and is generally connected into a star shape. The function of the rotating shaft is to support the rotor core and withstand a large torque. It is generally made of medium carbon steel. The end cover is generally cast iron, which is fixed on the machine base with screws to support the rotor and protect it. The bearing is installed in the bearing chamber in the middle of the end cover, and the bearing cover is used to fix the bearing to prevent the lubricating oil from flowing out and dust from entering the bearing.

The working principle of the three-phase motor: When the three-phase stator windings of the motor (each with a phase difference of 120° electric angle) pass through the three-phase symmetrical alternating current, a rotating magnetic field will be generated, which will cut the rotor winding, thereby generating induction in the rotor winding Current (the rotor winding is a closed path), the current-carrying rotor conductor will generate electromagnetic force under the action of the stator's rotating magnetic field, thereby forming an electromagnetic torque on the motor shaft, driving the motor to rotate, and the direction of rotation of the motor is the same as the direction of the rotating magnetic field. It can be seen from this that the three-phase asynchronous motor is composed of stator (fixed part), rotor (rotating part), end cover, bearing, terminal post, junction box, fan blade and fan cover and other parts. Specific functions: Stator - fix the motor, place the motor winding; rotor - rotate under the action of the stator's rotating magnetic field, output torque; end cover and bearing - support the rotor; terminal and junction box - fix the motor lead wire, protect Binding posts and protection against electric shock.