Servo drive is a high-end product of modern transmission technology, which is widely used in industrial robots and CNC machining centers and other automation equipment. In particular, the servo drive used to control AC permanent magnet synchronous motor has become a research hotspot at home and abroad. The current, speed and position-3 closed-loop control algorithm based on vector control is widely used in the design of AC servo drivers. Whether the speed closed-loop design in this algorithm is reasonable or not plays a key role in the whole servo control system, especially in the performance of speed control.
servo drives (servo drives), also known as “servo controller”, “servo amplifier”, is a controller used to control the servo motor, its role is similar to the frequency converter acting on the ordinary AC motor, is a part of the servo system, mainly used in high-precision positioning system. Generally, the servo motor is controlled through three ways of position, speed and torque to achieve high-precision transmission system positioning, and it is currently a high-end product of transmission technology.
In the speed closed loop of servo drive, the real-time speed measurement accuracy of motor rotor is very important to improve the dynamic and static characteristics of speed control of speed ring. In order to find the balance between measurement accuracy and system cost, incremental photoelectric encoder is generally used as the speed measurement sensor, and its corresponding common speed measurement method is M/T speed measurement. Although M/T velocity measurement method has a certain measurement accuracy and a wide measurement range, but this method has its inherent defects, including: 1) the speed measurement cycle must detect at least one complete code pulse, limiting the minimum measurable speed; 2) The timer switches of the two control systems used for speed measurement are difficult to maintain strict synchronization, and the accuracy of speed measurement cannot be guaranteed in the measurement occasions with large speed changes. Therefore, it is difficult to improve the performance of servo drive speed following and control by using the traditional speed loop design method.