Cage Rotor Motor

A. Stator of Cage rotor motor
1. The stator core is made of mutually insulated silicon steel sheets with a thickness of 0.50mm (cold-rolled silicon steel). There are evenly distributed slots on the inner circle of the silicon steel sheets, which are used to embed the three-phase windings of the stator.
2. Stator windings, three groups are wound with enameled wires and are symmetrically embedded in the same wire slots in the stator core slots (the slots are insulated with insulating paper and insulating cover paper). These three-phase windings can be connected in a star or star shape. triangle.
3. Frame: The Frame is made of cast iron or cast steel. Its function is to fix the core and windings.

Function of Stator of cage rotor motor

Generation of rotating magnetic field
The stator is the key part of the cage rotor motor that generates the rotating magnetic field. When three-phase alternating current flows into the stator windings, the magnetic fields generated by the three-phase currents in the inner space of the stator core synthesize into a rotating magnetic field because the three-phase currents differ from each other by an electrical angle of 120° in time. The rotational speed of this rotating magnetic field (which is the frequency of the power supply, is the number of poles of the motor). For example, the synchronous speed of the rotating field in a 4-pole cage rotor motor with a 50 Hz supply. This rotating magnetic field is like an invisible "power hand" and is the basis for the motor's ability to convert electrical energy into mechanical energy.
The arrangement of the stator windings and the way they are connected is critical to generating the correct rotating magnetic field. Usually three-phase double-layer windings or single-layer windings are used, and the number of turns, wire diameter and other parameters of the windings will be designed according to the motor's power, voltage and other requirements. There are two types of winding connections: star (Y) connection and triangle (△) connection, and different connection methods will affect the motor's performance in terms of voltage, current and power. For example, in the star connection, the line voltage is twice the phase voltage; in the delta connection, the line current is twice the phase current.
Establishing the motor's magnetic field circuit
The stator core is the main pathway for the motor's magnetic field. It is generally made of laminated silicon steel sheets, which have the characteristics of high permeability and low iron loss. When the stator windings are fed with current to generate a magnetic field, the magnetic field is mainly concentrated inside the core, forming a closed loop along the shape of the core. The establishment of this magnetic field loop enables the magnetic field to act effectively on the rotor, improving the electromagnetic conversion efficiency of the motor. Without the stator core, the magnetic field would leak heavily in the surrounding space and could not effectively drive the rotor to rotate.
The shape and size of the stator core also affects the performance of the motor. Usually, the inner diameter of the stator core determines the size of the rotor, while the outer diameter is related to factors such as the power and heat dissipation of the motor. For example, for high power cage rotor motors, the size of the stator core will be increased accordingly in order to be able to withstand a larger electromagnetic force and generate a sufficient magnetic field, and its structural design will also take into account a better way of heat dissipation to prevent the core from overheating and leading to a decrease in magnetic properties.
Interface for electrical energy input
The stator winding is the interface for the motor to receive electrical energy. An external three-phase AC power supply is connected to the terminals of the stator winding through a cable to feed electrical energy into the motor. In this process, the stator winding plays the role of directing the power supply electrical energy to the inside of the motor. According to the rated voltage and rated current of the motor, the stator winding's insulation level and wire cross-section area and other parameters will be designed accordingly. For example, for motors with high voltage ratings, the stator windings need to be insulated with a higher grade of insulating material to prevent insulation breakdown between the windings or between the windings and the iron core.
The resistance and inductance characteristics of the stator windings can also have an effect on the performance of the motor. Resistance causes electrical energy to be lost (it's current, it's resistance) in the windings, and this loss is emitted as heat, reducing the efficiency of the motor. Inductance, on the other hand, affects the reactive power and power factor of the motor. The performance of the motor can be optimized by reasonably designing the parameters of the stator winding. For example, reducing the winding resistance reduces copper losses and improves the efficiency of the motor; reasonably adjusting the inductance improves the power factor.
Determine the number of poles and synchronous speed of the motor
The number of poles of the stator winding determines the number of pole pairs of the motor, which in turn determines the synchronous speed of the rotating magnetic field of the motor. The number of poles is an important parameter of the motor, and different numbers of poles are suitable for different applications. For example, the synchronous speed of 2-pole motors is higher, suitable for occasions requiring high output speed, such as high-speed fans, small pumps, etc.; 4-pole motors have moderate synchronous speed, a wider range of applications, such as general industrial equipment drives, air conditioning compressors, etc.; 6-pole or 8-pole motors have lower synchronous speed, suitable for low-speed occasions requiring large torque output, such as cranes, conveyor belts, etc..
The number of poles of the motor can usually be determined by the distribution of the stator windings. In the manufacture of motors, the stator windings are divided into different phase bands according to the design requirements, and the number of windings in each phase band and the distribution position determine the number of poles of the motor. When selecting a motor, the user can determine the appropriate number of poles according to the actual application requirements (such as speed, torque, etc.), so as to select a suitable cage rotor motor.

B. Rotor of Cage rotor motor
1. The rotor core is made of 0.50mm thick, mutually insulated silicon steel sheets (cold-rolled silicon steel).

2. Rotor winding
1) Squirrel Cage - Squirrel Cage Asynchronous Motor (Cast Aluminum) 
2) Wound-wound asynchronous motor (wound copper wire)
3. Rotating shaft, mechanical load is added to the rotating shaft

Functions of the Cage Rotor Motor Rotor

Generation of electromagnetic torque
When a cage rotor motor is in operation, the stator winding is energized with a three-phase AC current to generate a rotating magnetic field. Due to the relative motion between the rotor guide bars and the rotating magnetic field, the rotor guide bars will cut the magnetic inductance to generate induced current. These guide bars with induced currents are in the rotating magnetic field. The forces on the many rotor guide bars form a combined force, which produces an electromagnetic torque which enables the rotor to follow the rotating magnetic field of the stator, thus converting electrical energy into mechanical energy. For example, in industrial applications, when a motor drives a conveyor belt, the electromagnetic torque acts on the rotor, causing it to rotate, which in turn drives the conveyor belt to move, realizing material conveying.
Regulating motor speed
The rotational speed of a cage rotor motor is closely related to the slew rate, which in turn is related to the operating condition of the rotor. The rotation rate (where is the synchronous speed of the stator rotating magnetic field and is the actual speed of the rotor). During the operation of the motor, when the load changes, the rotor speed changes accordingly, which leads to a change in the slew rate. For example, when the load increases, the rotor speed decreases and the slew rate increases. According to the principle of electromagnetic induction, the increase in the rate of divergence makes the speed of the rotor guide bars cutting the magnetic inductance relatively increase, the induced current increases, and the electromagnetic torque increases until the electromagnetic torque is re-balanced with the load torque, and the motor operates stably at the new speed.