Servo Motor Working Principle

AC servo motor is similar to phase-separated single-phase asynchronous motor, but the former rotor resistance is much greater than the latter. So compared to single-machine asynchronous motor, the servo motor has three significant features.

1, Starting torque

Due to the its large rotor resistance, it has significant difference compared to the general asynchronous motor torque. It can make the critical slip S0> 1, so that not only the torque characteristics (mechanical properties) closer to linear, but it also has a large starting torque. It has a fast start, high sensitivity characteristics. Therefore, when the stator control voltage, the rotor immediately turn.

2, A wide range of operation

3, No rotation phenomenon

Normal operation of the servo motor will immediately stop running as long as it loss the control voltage. When the servo motor loses its control voltage, it is in single-phase running state. Due to the large rotor resistance, two torque characteristics (T1-S1, T2-S2 curve) and the combined torque characteristics (T-S curves) generated by the rotating magnetic fields which rotating in opposite directions.

AC servo motor output power is generally 0.1-100W. When the power frequency is 50Hz, the voltage is 36V, 110V, 220, 380V; when the power frequency is 400Hz, the voltage is 20V, 26V, 36V, 115V and so on.

AC servo motor running smooth with low noise. But the control characteristic is non-linear. And because the rotor resistance is big, the loss is big, the efficiency is low. Therefore, compared with the same capacity direct current servomotor, the volume is big with heavy weight. It only applies to 0.5-100W small power control system.

Servo motor can control the speed and the position accuracy is very accurate; using such motor can improve the precision and quality of products!