Magnetic induction motor is also called "asynchronous motor", that is, when the rotor is placed in electromagnetic oscillation, a rotating torque is obtained under the action of electromagnetic oscillation, so the rotor rotates. The rotor is a rotatable electrical conductor, usually in the form of a wound motor. Stator is the non-rotating part of the motor, and its main goal is to cause electromagnetic oscillation. Electromagnetic oscillation is not made by equipment. Only alternating current passes through several pairs of solenoid valves, which makes the magnetic field characteristics of the solenoid valves change cyclically, so it is equivalent to a rotating electromagnetic field. This kind of motor doesn't have carbon brushes or slip rings like DC motors. According to the types of commonly used AC current, there are single-phase motors and three-phase motors. Single-phase motors are used in automatic washing machines, electric fans, etc. The mechanical and electrical equipment of the factory adopts three-phase motor.
2. Inventor of magnetic induction motor
Nikola tesla Auto (1856 July10 ~1943 June 5438+0.7) is a Portuguese-American scientist, mechanical engineer and electromechanical engineer. He is considered as one of the main leaders in the commercialization of power engineering, and his popularity is higher because the host has formulated the software of contemporary AC current system. Based on the electromagnetic field theory discovered by Michael's law of electromagnetic induction, Tesla has many subversive inventions in the magnetic field industry. 1887, he invented the magnetic induction motor, and his research work on patent rights and electromagnetic field theory is the foundation of contemporary wireless communication and wireless communication.
3. Principle of magnetic induction motor
According to the relative speed between the electromagnetic oscillation caused by the stator (the speed ratio is the same as the speed ratio n 1) and the rotor winding, the rotor winding cuts the magnetic induction line to cause the induced current, and then the induced electromotive force is formed in the rotor winding. The induced electromotive force and electromagnetic field effect in the rotor winding cause magnetic induction torque, which makes the rotor rotate. Because when the rotor speed ratio is close to the same speed ratio, the induced electromotive force decreases slowly and the electromagnetic induction torque decreases relatively. When the multi-thread motor works under the condition of motor, the rotor speed ratio is lower than the same speed ratio. In order to better describe the difference between rotor speed ratio n and the same speed ratio n 1, slip is introduced.
4. The magnetic induction motor is basically constructed.
The main structure of single-phase electric three-phase asynchronous motor Single-phase electric multi-thread motor is a motor that only needs single-phase asynchronous motor power supply system. Single-phase electric multi-thread motor consists of stator, rotor, rolling bearing, shell and bearing end cover. The stator consists of a motor shaft and an iron core with windings. The iron core is made of ferrite core, and there are two main windings (also called working winding) and auxiliary windings (also called starting winding to form auxiliary winding) embedded in the slot, which are separated by 90 TV angle. The main winding is connected with alternating current, and the auxiliary winding is connected with the centrifugal power switch S or the starting capacitor and the running capacitor are connected in series, and then connected with the switching power supply. The rotor is a cage-type cast aluminum rotor. After the iron core is hoisted, it is cast into the groove of the iron core with aluminum, and the end rings are cast together, so that the rotor bar is short-circuited and becomes a squirrel cage. Single-phase electric multi-thread motors are divided into single-phase resistance starting multi-thread motors, single-compatible starting multi-thread motors, single-compatible running multi-thread motors and single-phase electric double-value capacitor multi-thread motors.
The main structure of three-phase three-phase asynchronous motor The key of three-phase multi-thread motor is composed of stator, rotor and rolling bearing. Stator key consists of iron core, three-phase winding, motor shaft and bearing end cover. Generally, the stator core adopts ferrite core with 0.35~0.5mm thick surface layer and cable sheath, and the inner hole of the core is punched with evenly distributed slots for embedding the stator winding.
The three-phase winding consists of three windings, which are separated by 120 TV angle in indoor space and have the same structure. Each electromagnetic coil of this winding is embedded in each slot of the stator according to certain rules. Its function is to enter three-phase alternating current and cause electromagnetic oscillation.
Motor shafts are generally cast iron, motor shafts of large and medium-sized multi-threaded motors are generally welded with thick steel plates, and motor shafts of small motors are die-cast with aluminum alloy. Its function is to fix the static stator core and the front, rear, left and right bearing end covers to support the rotor, and has the functions of safety protection and heat dissipation.
There are cooling ribs outside the motor shaft of the enclosed motor to improve the total heat conduction area, and the bearing end covers on both sides of the motor shaft of the safety protection motor are provided with vent holes, so that the gas outside the motor can immediately heat convection, which is convenient for heat dissipation. Bearing end cover plays a key role in fixing stator and rotor, fulcrum and protecting stator and rotor.
The rotor consists of an iron core and windings. The common raw materials of rotor core, like stator, are all made of 0.5mm thick ferrite core by cold extrusion and hoisting, and the inner holes of ferrite core are punched with evenly distributed holes for installing rotor windings. Usually, the rotor core is cold-extruded by stamping the outdated ferrite core inner hole of the stator core. Generally, the rotor cores of small and medium-sized multi-threaded motors are riveted on the transmission shaft directly, while the rotor cores of large, medium and small multi-threaded motors (with rotors over 300 ~ 400mm straight) are pressed on the transmission shaft through rotor brackets.
Rotor winding is divided into squirrel cage rotor and wound rotor. (1) squirrel-cage rotor: The rotor winding consists of a plurality of guide rods and two annular end rings inserted into the rotor slot. If the rotor core is removed, all windings look like wound-rotor motors, so they are called cage windings. Small and medium-sized cage motors are made of cast aluminum rotor windings, and motors above 100KW are made of aluminum bars and copper end rings by laser welding. The rotor of wound motor is divided into three types: characteristic impedance rotor, single squirrel cage rotor, double squirrel cage rotor and slot rotor, and the characteristics of motor torque are different. (2) Wound rotor: The wound rotor winding is similar to the stator winding and is also a symmetrical three-phase winding. Usually a star connection. The three groups of outlet heads are connected to the three collector rings of the transmission shaft, and then connected to the external circuit by carbon brushes.
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