1, AC servo motor
     AC servo motor stator structure is basically the capacitor split-phase similar to single-phase induction motors. Its stator is equipped with a 90 ° difference of two places in each of the windings, one field winding Rf, it is always connected to the AC voltage Uf; the other is to control the winding L, connect the control signal voltage Uc. Therefore, AC servo motor also known as the two servo motors.
    AC servo motors are usually made of squirrel-cage rotor, but in order to make servo motor has a wide speed range, the linear mechanical properties, no "rotation" phenomenon and the rapid response performance, which, compared with ordinary motor should be rotor resistance with a small amount of large and moment of inertia of these two characteristics. The rotor structure is currently used more often, there are two forms: one is high resistivity conductive material made of high resistivity of Article I. squirrel cage rotor, in order to reduce the moment of inertia of the rotor, rotor done slender; the other One is made of hollow aluminum cup-shaped rotor, Beibi thin, only 0.2-0.3mm, in order to reduce the magnetic circuit reluctance, to be placed inside the hollow cup-shaped rotor fixed-designated child. hollow cup-shaped Rotor moment of inertia is very small, responsive, and stable operation, it has been widely adopted.
    AC servo motor in the absence of control voltage, the stator windings, only the excitation pulse of the magnetic field generated by the rotor stationary. When a control voltage, the stator produces a rotating magnetic field within a matter of the rotor rotating magnetic field along the direction of rotation, in the case of a constant load, the motor speed control voltage with the size of the changes, when the control voltage of the phase contrast, the servo motor will be reversed.
    AC servo motor works and sub-phase single-phase induction motor although similar, but the former is the rotor resistance is much greater than the latter, so induction motor servo motor, compared with the stand-alone, there are three notable features:
    1, high starting torque
    As the rotor resistance large, the torque characteristic curve shown in Figure 3, curve 1, with normal induction motor torque characteristic curve of two comparison, there are clear differences. It will enable the critical slip S0> 1, so not only the torque characteristics (mechanical properties) is closer to linear, but also has a larger starting torque. Thus, when there is a control voltage of the stator, rotor rotation immediately, ie start fast, high sensitivity characteristics.
    2, run a wider range of
    3, no rotation of the phenomenon of
    Normal operation of the servo motor, as long as the loss of control voltage, motor stops immediately. When the servo motor voltage is out of control, it is in single-phase running, due to large rotor resistance, stator in two opposite directions of rotation with the rotor rotating magnetic field generated by the role of the two torque characteristics (T1-S1, T2-S2 curves ), and the synthesis of torque characteristics (T-S curve)
    AC servo motor output power is generally 0.1-100W. When the power frequency is 50Hz, voltage 36V, 110V, 220,380 V; when the power frequency is 400Hz, voltage 20V, 26V, 36V, 115V and so on.
    AC servo motor to run smoothly noise. But the control feature is non-linear, and the rotor resistance due to big, big loss, low efficiency, so DC servo motors with the same volume compared to bulky weight, it only applies to 0.5-100W low-power control system.