The structure of AC servo motor can be mainly divided into two parts, namely the stator part and the rotor part. The structure of the stator is basically the same as that of the resolver, and a two-phase winding with an electric angle of 90 degrees is also placed in the center of the stator. One of them is the excitation winding, the other is the control winding, and the AC servo motor is a two-phase AC motor. When the AC servo motor is used, a constant excitation voltage Uf is applied at both ends of the excitation winding, and a control voltage Uk is applied at both ends of the control winding. When voltage is added to the stator windings, the servo motor will soon turn around. The current that enters the excitation winding and the control winding generates a rotating magnetic field in the motor, and the steering of the rotating magnetic field determines the steering of the motor, and when the voltage added to any one of the windings is inverted, the direction of the rotating magnetic field changes, and the direction of the motor also changes. In order to form a circular rotating magnetic field in the motor, a phase difference of 90 degrees between the excitation voltage Uf and the control voltage UK is required.

1) The phase voltage and line voltage of the three-phase power supply are used to form a phase shift of 90 degrees
2) Arbitrary line voltage using a three-phase power supply
3) Phase-shifting network is adopted
4) Connect the capacitors in series in the excitation phase