What is the principle and operation of the machine control circuit of an induction motor?

An induction motor usually consists of two parts: the stator and the rotor. The stator is the stationary part of the motor and consists of the stator core, windings, and end caps. Three-phase staggered winding coils are distributed in the winding, and when three-phase power is connected to the winding, a rotating magnetic field is formed in the winding.

The rotor is the rotating part of the motor and usually consists of a rotor core and conductor bars. The conductor bars of the rotor are usually made of aluminium, copper and other good conductive materials and are fixed on the rotor core. When the rotating magnetic field passes through the rotor conductor bars, the induced electromotive force will generate a current inside the conductor bars, and the rotor will be subjected to a certain amount of torque because the current inside the conductor bars is subjected to electromagnetic force.

Depending on how the magnetic field is generated, induction motors can be classified into two types, which are asynchronous motors and synchronous motors. An asynchronous motor is the most common type of induction motor, in which the rotor rotates at a slightly lower speed than the magnetic field, called slip. Synchronous motors, on the other hand, are motors whose rotational speed is exactly the same as the rotational speed of the magnetic field.

In summary, the basic operating principle of an induction motor is to form a rotating magnetic field in the stator coil through the principle of electromagnetic induction, thereby generating a rotating magnetic field within the rotor, which drives the motor to rotate through the torque generated by the induced current. This type of motor has the advantages of simple structure, high reliability and stable operation, and is one of the main types of motors widely used in various industrial and civil fields.

Working mode of induction motor

Induction motors work according to the law of electromagnetic induction, using a rotating magnetic field to generate an induced current in the rotor, which causes the rotor to rotate and drive the load movement.

An induction motor usually consists of two parts: a stator and a rotor. The stator is the stationary part of the motor and consists of the stator core, windings and end caps. Three-phase staggered winding coils are distributed in the winding, and when three-phase power is connected to the winding, a rotating magnetic field is formed in the winding.

The rotor is the rotating part of the motor and usually consists of a rotor core and conductor bars. The conductor bars of the rotor are usually made of a good conducting material such as aluminium or copper and are fixed to the rotor core. When an alternating current is applied to the stator winding, a rotating magnetic field is generated in the winding, which passes through the rotor core and induces an electromotive force in the conductor bars. Since the resistance inside the conductor strip is not zero, currents are generated in the conductor strip. These currents are in the opposite direction to the rotor magnetic field, so they interact with the rotating magnetic field to produce torque. The rotor turns in the same direction as the rotating magnetic field, so the relative velocity between them is small.

Induction motors are also known as asynchronous motors due to the presence of induced currents in the rotor because the rotor rotates at a speed slightly lower than the speed of the rotating magnetic field, and this speed difference is known as slip. When the load resistance increases, the rotor decelerates and the slip increases, resulting in a greater torque. This characteristic enables the induction motor to automatically adjust its output power under large load variations and has good load adaptability.

In conclusion, the induction motor works by using a rotating magnetic field to generate an induced current in the rotor, which generates torque and drives the load to rotate. This kind of motor has the advantages of simple structure, high reliability, stable operation, etc. It is one of the main types of motors widely used in various industrial and civil fields.