The rotor is a rotating part of a three-phase asynchronous motor consisting of a rotor core, a rotor winding, a rotating shaft and a fan. The iron core of the rotor is also part of the magnetic circuit of the motor, which is superposed by a silicon steel sheet with a uniform groove on the outer circumference and fixed on the rotating shaft. A rotor winding is placed in the slot of the rotor core. According to the structure of the rotor winding, three-phase asynchronous motor can be divided into two kinds of squirrel cage and winding type.
The rotor winding of squirrel cage induction motor is named as cage because of its shape. The structure of the rotor is embedded with copper bars in the slot, and the ends of the copper bars are welded with short circuited rings. Medium and small squirrel cage induction motors adopt cheaper aluminum instead of copper. The rotor, conductor, short circuit ring and fan are integrated into a cast aluminum squirrel cage rotor.
The core of the wound rotor is the same as the core of the squirrel cage rotor.
The rotor winding is similar to the stator winding. It is formed by winding an insulated wire and is embedded in the rotor slot according to certain rules to form a three-phase symmetrical winding. Usually, the ends of the three windings are connected together, and the first end is respectively connected with three insulated copper slip rings fixed on the rotating shaft and connected into a star shape. The rotor winding is connected with an additional three-phase rheostat through the slip ring and the brush on it, and is used for motor starting and speed regulation in a small range. The working principle of squirrel cage and wound three-phase asynchronous motors is the same, but the difference is only in the difference of rotor winding structure