The working principle of wound motor is the same as that of asynchronous motor. They all rely on the stator winding to generate a rotating magnetic field on the stator core. The rotating magnetic field cuts the fixed rotor winding coil and generates induced current in the rotor winding. The induced current is pulled by the rotating magnetic field of the stator to generate a rotating torque, and the rotor rotates. The difference is that the rotor of the wound motor can be externally connected with a frequency-sensitive rheostat or resistor to start or adjust the torque. When the motor is started, the rotor does not move, so the frequency of the induced current generated in the rotor at this time is also 50HZ, and this high-frequency induced current will be blocked by the frequency-sensitive rheostat. When the rotor rotates and starts, the frequency of the induced current in the rotor will be very low, and this low-frequency induced current will not be affected by the frequency-sensitive rheostat, so after the motor starts, the frequency-sensitive rheostat has almost no effect. Excitation winding and armature winding generally refer to DC motor, but you can understand that excitation winding is a winding that generates magnetic field, and armature winding is a winding in which current flows and is pulled by the magnetic field generated by excitation winding. Generally, in a DC motor, the excitation winding is the stator and the armature winding is the rotor.