An electric motor (Motor) is a device that converts electrical energy into mechanical energy. It is through the electric coil (i.e. stator winding) and produce a rotating magnetic field acting on the rotor (such as the squirrel cage closed aluminum frame) formed magnetoelectric rotary torque. Use the power of the motor according to the different DC motor and AC motor, motor power system in most of the AC motor can be synchronous or asynchronous motor (motor rotation speed of motor stator and rotor magnetic speed keeps synchronous speed). The motor is mainly composed of stator and rotor. The direction of force acting on the conducting wire in the magnetic field is related to the direction of the current and the direction of the magnetic induction line (the direction of the magnetic field). The working principle of the motor is that the magnetic field acts on the force of the current, so that the motor rotates.