From the roaring production line in the factory to the running fan at home, induction motors are everywhere, providing power for our production and life. In this device, the stator and rotor are its “heart”. Their exquisite structure and coordinated work realize the efficient conversion of electrical energy into mechanical energy. So, what do the stator and rotor of an induction motor look like? What role do they play? This article will disassemble it for you in detail.
Stator structure
The stator of an induction motor is mainly composed of three parts: stator core, stator winding and frame. The stator core is an important part of the motor magnetic circuit. It is made of 0.5 mm thick silicon steel sheets stacked together. The surface of the silicon steel sheets is coated with insulating paint. This design can reduce hysteresis and eddy current losses and enhance magnetic conductivity. There are many slots evenly distributed on the inner circle of the core for placing stator windings.
The stator winding is the circuit part of the stator, usually wound with high-strength enameled wire. The stator winding of a three-phase induction motor is divided into three independent parts, which are 120 degrees apart and embedded in the core slots according to a specific rule. When three-phase alternating current is passed into the stator winding, a rotating magnetic field is generated in space, which is the basis for the operation of the induction motor. The base plays the role of supporting and fixing the stator core and the end cover. It is generally made of cast iron or cast aluminum. It is required to have sufficient mechanical strength and heat dissipation capacity to ensure the stable operation of the motor.
Rotor structure
The rotor is mainly composed of the rotor core, rotor winding and shaft. The rotor core is also made of laminated silicon steel sheets, which together with the stator core constitute the magnetic circuit of the motor. There are evenly distributed slots on the outer circle of the rotor core for placing the rotor winding.
According to the different winding forms, the rotor can be divided into two types: squirrel cage type and winding type. The squirrel cage rotor is the most common type. Its winding consists of several conductive bars and end rings, and its shape resembles a squirrel cage. The conductive bars are generally made of copper or aluminum, and the two ends are welded or cast together with the end rings to form a closed loop. This structure is simple, strong, low-cost and reliable, and is widely used in various small and medium-sized induction motors. The winding of the wound rotor is similar to the stator winding. It is wound by insulated wire and connected to the external circuit through slip rings and brushes. The advantage of this structure is that a resistor can be connected in series in the rotor circuit to improve the starting performance and speed regulation performance of the motor. It is often used in situations where starting and speed regulation are required.
The shaft is a key component for the motor to transmit torque. It is usually made of medium carbon steel and supported on bearings at both ends to ensure that the rotor can rotate flexibly and transmit the mechanical energy generated by the rotor to the load.
Collaborative work
When the stator winding is connected to a three-phase alternating current to generate a rotating magnetic field, the rotor conductor cuts the magnetic flux lines due to relative motion with the rotating magnetic field to generate induced electromotive force and induced current. The induced current is affected by the electromagnetic force in the rotating magnetic field, forming an electromagnetic torque and driving the rotor to rotate. The rotor speed is slightly lower than the rotating magnetic field speed. This speed difference ensures the continuous electromagnetic induction, so that the motor can output mechanical energy stably.
The stator and rotor of an induction motor are responsible for generating a magnetic field and converting the magnetic field energy into mechanical energy, respectively. The two are inseparable. It is this exquisite structural design and working principle that makes induction motors an indispensable power device in modern industry and daily life. Understanding their structure and working methods can not only help us better use and maintain motors, but also give us a deeper understanding of the technological power around us.