Introduction

      Servo motor (servo motor), also known as the implementation of the motor, is in the servo system to control the operation of mechanical components of the engine, is an auxiliary motor indirect transmission. It can control the speed, position accuracy is very accurate, can be voltage signals into torque and speed to drive the control object. Servo motor can be divided into DC servo motor and AC servo motor. It can be used for cost-sensitive general industrial and civil applications.

Basic structure of servo motor

      AC servo motor is also composed of the stator and rotor. The structure of the stator is basically similar to that of the capacitor split phase single-phase asynchronous motor. Its stator is equipped with two windings which are located at 90 ° from each other. One is the field winding Rf, which is always connected to the AC voltage Uf. A control winding L, and a connection control signal voltage Uc. Therefore, AC servo motor, also known as two servo motor.

     AC servo motor rotor is usually made of squirrel cage, but in order to make the servo motor has a wide speed range, linear mechanical properties, no "rotation" phenomenon and rapid response performance, compared with ordinary motor, it should have Large rotor resistance and small moment of inertia of these two characteristics.

Servo motor works

     AC servo motor and two-phase asynchronous motor is similar to the principle. But because it is in the CNC machine tool as the implementation of components, the AC signal is converted to angular displacement or angular velocity on the shaft, so the rotor speed required to reflect the control signal phase, no control signal when it does not rotate.

     Since the two windings on the stator are electrically different by 90 ° in space, a circular rotating magnetic field is generated in the air gap of the motor if the symmetrical voltage of 90 ° electrical phase with the same amplitude and phase difference is applied to the two-phase windings. If the magnitude of the two voltages is unequal or the phase is not 90 ° electrical, the resulting magnetic field will be an elliptical rotating field. The signal applied to the control winding is different, resulting in a different magnetic field ellipticity.

     The internal rotor of the servo motor is a permanent magnet, and the U / V / W three-phase motor controlled by the driver forms an electromagnetic field. The rotor rotates under the influence of this magnetic field, and the encoder feedback signal is supplied to the driver. The driver calculates the feedback value Value to compare, adjust the angle of rotor rotation.