Three phase asynchronous motor rotor speed below the speed of a rotating magnetic, the rotor winding magnetic field between the relative motion and the induced electromotive force and current, and electromagnetic torque and magnetic field interaction, realize the energy transformation. Compared with the single-phase asynchronous motor, the three-phase asynchronous motor has good performance and saves various materials. According to the structure of the rotor, the three-phase asynchronous motor can be divided into two kinds of cage and winding. The squirrel cage rotor asynchronous motor is widely used because of its simple structure, reliable operation, light weight and cheap price. Winding three-phase asynchronous motor rotor and stator is also provided with three-phase winding, and through the slip ring, brush and external rheostat connection. Adjusting rheostat resistance can improve the starting performance of motor and adjust the speed of motor. The utility model has the advantages of high efficiency, energy saving, good performance, small vibration, low noise, long service life, high reliability, convenient maintenance, large starting torque, etc.