Basic Introduction to Servo drives

- Nov 06, 2018-

Servo driver is an important part of modern motion control, which is widely used in automation equipment such as industrial robot and NC machining center. In particular, the servo driver used to control AC permanent magnet synchronous motor has become a research hotspot at home and abroad. At present, the current, velocity and position 3 closed-loop control algorithm based on vector control is widely used in AC servo drive design.

The speed closed-loop design of the algorithm is reasonable, which plays a key role in the whole servo control system, especially the speed control performance [1]. In servo drive speed closed loop, the real-time speed measurement accuracy of motor rotor is very important to improve the dynamic and static characteristics of speed loop. In order to find the balance between measurement accuracy and system cost, an incremental photoelectric encoder is generally used as a speed sensor, and its corresponding common speed measurement method is m/t velocity measurement. Although the m/t velocity method has certain measurement accuracy and wide measuring range, this method has its inherent defects, including: 1) at least one complete code disk pulse must be detected during the speed measurement period, which limits the minimum measurable speed, 2) the timer switch of 2 control system for speed measurement is difficult to keep in strict synchronization, The accuracy of velocity measurement cannot be guaranteed in measuring situations with large speed changes.

Therefore, it is difficult to improve the speed follow and control performance of servo drive by using the traditional speed loop design scheme of the velocity measurement method.