In order to achieve better performance of servo motor, it is necessary to understand some characteristics of servo motor.
Noise, unstable
When using a servo motor, it often causes excessive noise and unstable operation of the load driven by the motor. When this problem occurs, the first reaction of many users is that the quality of the servo motor is poor, because sometimes it is replaced by a stepper motor or a variable frequency motor to drag the load, but the noise and instability are much smaller. On the surface, it is really the servo motor, but after carefully analyzing the working principle of the servo motor, we will find that this conclusion is completely wrong.
AC servo system includes: servo drive, servo motor and a feedback sensor (generally the servo motor is equipped with optical polarizer). All these components operate in a control closed-loop system: the driver receives parameter information from the outside, and then transmits a certain current to the motor. The motor converts it into torque to drive the load. The load acts or accelerates or decelerates according to its own characteristics. The sensor measures the position of the load, so that the drive device compares the set information value with the actual position value, Then the actual position value is consistent with the set information value by changing the motor current. When the speed changes due to sudden change of load, the code deflector will immediately respond to the servo driver after knowing the speed change, and the driver will meet the load change by changing the current value provided to the servo motor, and return to the set speed.
The AC servo system is a fully closed loop system with very high response. The time lag response between load fluctuation and speed correction is very fast. At this time, the transmission time of the mechanical connection device really limits the response effect of the system. Look at the error and alarm number on the drive, and then check the manual. If there is no alarm, it is the driver fault. Of course, there may be no servo fault at all, but the control signal error leads to no servo action. In addition to looking at the error and alarm number on the servo drive, and then looking up the manual, sometimes the most direct way to judge is to replace, such as the X and Z axis servo (only with the same model). Or modify the parameters, such as locking the X axis to prevent the system from detecting the X axis. However, it should be noted that the X axis is interchangeable with the Z axis. Even if the model is the same, the imported equipment may have problems due to different loads and parameters.
Of course, if it is a domestic equipment, the servo parameters will not be adjusted according to the use situation, and generally there will be no problem. However, attention should be paid to whether the power and torque of the X-axis and Z-axis motors are the same, whether the motor lead screw is directly connected, and the electronic gear reduction ratio.
Several questions about AC servo motor: related, synchronous speed n1=60f/2p, asynchronous motor has slip s, n=(1-s) n1, synchronous motor n=n1, 2p is polar logarithm. The definition of magnetic weakening speed in control is determined by the driver. The rated speed can be determined by several aspects: the back EMF of the synchronous servo, the allowable driving current alternating frequency of the motor core material, the maximum power of the motor under the rated torque, the maximum temperature rise, etc., the most important is the back EMF; Asynchronous motors are mainly limited by the maximum allowable frequency of materials and the number of poles. The definition of rated speed is determined by the mechanical and electrical characteristics of the motor itself. Answer: AC servo usually refers to servo driven by sine wave. Brushless drive is equivalent to 6 commutators.
Source: Rihong Zhongxin
