What is the principle of AC servo controller

The structure of the stator of the AC servo controller is basically similar to that of a capacitor split phase single-phase asynchronous motor. The stator is equipped with two windings with a position difference of 90 ° each other, one of which is the excitation winding Rf, which is always connected to the AC voltage Uf; The other is to control winding L and connect the control signal voltage Uc. So AC servo motors are also known as two servo motors.

The rotor of an AC servo controller is usually made into a squirrel cage type, but in order to make the AC servo controller have a wide speed range, linear mechanical characteristics, no "rotation" phenomenon, and fast response performance, it should have two characteristics compared to ordinary motors: high rotor resistance and small rotational inertia. At present, there are two types of rotor structures that are widely used: one is a squirrel cage rotor made of high resistivity conductive materials with high resistivity conductive bars. In order to reduce the rotational inertia of the rotor, the rotor is made slender; Another type is a hollow cup rotor made of aluminum alloy, with a thin cup wall of only 0.2-0.3mm. In order to reduce the magnetic resistance of the magnetic circuit, a fixed inner stator needs to be placed inside the hollow cup rotor. The hollow cup rotor has a small moment of inertia, rapid reaction, and smooth operation, so it is widely used. When there is no control voltage in the AC servo motor, only the pulsating magnetic field generated by the excitation winding in the stator, and the rotor remains stationary. When there is a control voltage, a rotating magnetic field is generated in the stator, and the rotor rotates in the direction of the rotating magnetic field. Under constant load, the speed of the motor changes with the magnitude of the control voltage. When the phase of the control voltage is opposite, the AC servo controller will reverse.