Rotor (rotating part)
1, the rotor core of a three-phase asynchronous motor:
Function: as part of the magnetic circuit of the motor and the rotor winding in the core slot.
Structure: the material used is similar to the stator, which is punched and laminated by 0.5 millimeter thick silicon steel sheet. The silicon steel sheet is punched evenly distributed holes to set up the rotor windings. The inner circle of the silicon steel sheet is usually flush with the stator core to make the rotor core. The rotor core of a small asynchronous motor is directly mounted on a rotating shaft, and the rotor core of a large and medium asynchronous motor (with a rotor diameter of 300~400 mm or more) is pressed on the shaft with the support of the rotor.
2, the rotor winding of three phase asynchronous motor
Function: the rotating magnetic field of the stator is cut to produce the induction electromotive force and the current, and the electromagnetic torque is formed to make the motor rotate.
Structure: it is divided into squirrel cage rotor and winding rotor.
(1) a squirrel cage rotor: the rotor winding is composed of multiple guide bars inserted into the rotor slot and two ring end rings. If the rotor core is removed, the shape of the whole winding is like a squirrel cage, so it is called a cage type winding. The small cage motor is made of cast aluminum rotor winding, which is welded by copper strip and copper end ring for more than 100KW motor.
(2) the wound rotor winding and stator, rotor winding, three-phase winding is a symmetric, usually connected into a star, three outlet end to the three shaft slip ring, and then through the brush and external circuit connection.
Characteristics: the structure is more complex, so the application of the winding motor is not as wide as the squirrel cage motor. But on other components of additional resistance in the rotor winding loop through the slip ring and brush, in order to improve the asynchronous motor starting and braking performance and speed performance, the requirements for smooth speed in a range of devices, such as crane, elevator, air compressor and so on by.