A, AC asynchronous motor
AC asynchronous motor is the leading AC voltage operation of the motor, widely used in electric fans, refrigerators, washing machines, air conditioners, hairdryers, vacuum cleaners, hoods, dishwashers, electric sewing machines, food processing machines and other household appliances and a variety of power tools, small electromechanical equipment.
AC asynchronous motor is divided into induction motor and AC commutator motor. Induction motors are further divided into single-phase asynchronous motors, AC and DC motors and push repulsion motors.
The speed of the motor (rotor speed) is less than the speed of the rotating magnetic field, thus called asynchronous motor. It is basically the same as an induction motor. s=(ns-n)/ns. s is the rate of rotation,
ns is the rotational speed of the magnetic field and n is the rotor speed.
Basic principle:
1, when the three-phase asynchronous motor is connected to the three-phase AC power supply, the three-phase stator windings flow through the three-phase symmetrical currents generated by the three-phase magnetic potential (stator rotating magnetic potential) and produce a rotating magnetic field.
2, the rotating magnetic field and the rotor conductor has a relative cutting motion, according to the principle of electromagnetic induction, the rotor conductor generates induction electromotive force and generates induction current.
3, according to the law of electromagnetism, the current-carrying rotor conductor is subjected to electromagnetic force in the magnetic field, which forms electromagnetic torque and drives the rotor to rotate, and outputs mechanical energy outwardly when a mechanical load is carried on the motor shaft.
The asynchronous motor is a kind of alternating current motor, and its rotational speed when loaded is not constant in relation to the ratio of the frequency of the connected grid. It also changes with the size of the load. The greater the load torque, the lower the rotor speed. Asynchronous motors include induction motors, double-fed asynchronous motors and AC commutator motors. Induction motors are the most widely used, and without causing misunderstanding or confusion, induction motors can generally be referred to as asynchronous motors.
The stator winding of an ordinary asynchronous motor is connected to the AC power grid, and the rotor winding does not need to be connected to any other power source. Therefore, it has the advantages of simple structure, easy manufacture, use and maintenance, reliable operation as well as smaller mass and lower cost. Asynchronous motor has higher operating efficiency and better operating characteristics, from no load to full load range close to constant speed operation, can meet most of the industrial and agricultural production machinery transmission requirements. Asynchronous motor is also easy to generate a variety of protection type, to adapt to the needs of different environmental conditions. Asynchronous motor operation, must draw reactive excitation power from the grid, so that the power factor of the grid becomes bad. Therefore, to drive ball mills, compressors and other high-power, low-speed mechanical equipment, often using synchronous motors. Because the speed of the asynchronous motor and its rotating magnetic field speed has a certain rotational relationship, its speed regulation performance is poor (except for AC commutator motor). Requirements for a wide and smooth speed range of transportation machinery, rolling mills, large machine tools, printing and dyeing and paper machinery, etc., the use of DC motors is more economical and convenient. But with the development of high-power electronic devices and AC speed control system, suitable for wide speed regulation of asynchronous motor speed performance and economy has been comparable to the DC motor.
Two, single-phase asynchronous motor
Single-phase asynchronous motor by the stator, rotor, bearings, casing, end caps and other components.
The stator consists of a seat and a core with windings. The core is made of silicon steel sheet punching groove stacked into, groove embedded in two sets of space between each other 90 ° electrical angle of the main winding (also known as the operation of the winding) and auxiliary winding (also known as the starting winding into the sub-winding). The main winding is connected to the AC power supply, and the auxiliary winding is connected to the power supply after connecting the centrifugal switch S or the starting capacitor, running capacitor, etc. in series.
The rotor is a cage-type cast aluminum rotor, which is stacked with aluminum cast into the slot of the core, and cast together with the end ring, so that the rotor guide short-circuited into a rat-cage type.
Single-phase asynchronous motor is also divided into single-phase resistance starting asynchronous motor, single-phase capacitor starting asynchronous motor, single-phase capacitor running asynchronous motor and single-phase double-value capacitor asynchronous motor.
Three, three-phase asynchronous motor
Three-phase asynchronous motor structure and single-phase asynchronous motor is similar to the stator core groove embedded in three-phase windings (single-layer chain, single-layer concentric and single-layer crossover three structures). After the stator winding is connected to the three-phase AC power supply, the rotating magnetic field generated by the winding current produces an induced current in the rotor conductor, and the rotor produces an electromagnetic rotating cabinet (i.e., asynchronous rotating cabinet) under the interaction of the induced current and the rotating magnetic field of the air gap, which makes the motor rotate.
Four, shaded-pole motor
Shaded-pole motor is a one-way AC motor in the simplest one, usually using a cage-type slotted cast aluminum rotor. It is divided into convex-pole shaded-pole motors and hidden-pole shaded-pole motors according to the different stator structures.
Convex shaded-pole motor stator core shape for the square, rectangular or circular magnetic field frame, magnetic poles protruding, each pole has one or more auxiliary role of the short-circuit copper ring, that is, the cover pole winding. Concentrated winding on the convex pole magnetic poles as the main winding.
Hidden-pole shaded-pole motor stator core and ordinary single-phase motor core is the same, the stator winding distribution winding, the main winding is distributed in the stator groove, shaded-pole winding does not use short-circuiting copper ring, but with a thicker enameled wire wound into a distribution winding (short-circuiting itself after series connection) embedded in the stator groove (about 2/3 of the total number of grooves), to play the role of auxiliary group. The main winding and the shaded-pole winding are separated by a certain angle in space.
When the main winding of a shaded-pole motor is energized, the shaded-pole winding also generates an induced current, causing the magnetic flux in the part of the stator pole that is shaded by the shaded-pole winding to rotate with the unshrouded portion in the direction of the shaded portion.
Fifth, single-phase series-excited motor
Single-phase series-excited motor stator consists of convex pole core and excitation winding, rotor consists of hidden pole core, armature winding, commutator and rotor shaft and other components. Between the excitation winding and armature winding, a series circuit is formed through brushes and commutator.
Single-phase series-excited motor belongs to AC and DC motors, which can work with AC power supply as well as DC power supply.