Servo motor is often used in automation equipment, especially position control. Most brands of servo motor have position control function. The controller sends out pulses to control the operation of the servo motor. To ensure that the motor is noise-free, as far as possible, the moment of inertia ratio is also very important. It can be referred to by the number set by self-learning, and then set the speed gain and speed integration time to ensure that the continuous operation at low speed and the position accuracy can be controlled.
(1) Position proportional gain
Set the proportional gain of the position loop regulator. The larger the setting value, the higher the gain, the larger the stiffness, and the smaller the position lag under the same frequency instruction pulse condition. But too large a value may cause oscillations or overshoot. Parameter values are determined by the specific servo system model and load condition.
(2) Position feedforward gain
Set the feedforward gain of the position loop. The larger the set value, the smaller the position lag under any frequency of instruction pulse, the larger the feedforward gain of the position loop, the higher the high-speed response characteristics of the control system, but it will make the position of the system unstable, easy to produce oscillation. If high response characteristics are not required, this parameter is usually set to 0, indicating the range from 0 to 100%.
(3) proportional gain of velocity
Set the proportional gain of the speed regulator. The higher the setting value, the higher the gain and the higher the stiffness. The parameter value is determined according to the specific servo drive system model and load value. In general, the larger the load inertia, the larger the set value. Under the condition that the system does not produce oscillation, try to set a large value.
(4) Time constant of velocity integration
Set the integral time constant of the speed regulator. The smaller the setting value, the faster the integration speed. Parameter values are determined according to the specific servo drive system model and load. In general, the larger the load inertia, the larger the set value. Under the condition that the system does not produce oscillation, try to set a small value.
(5) velocity feedback filter factor
Set the speed feedback low pass filter characteristics. The larger the value, the lower the cutoff frequency and the smaller the noise generated by the motor. If the load inertia is large, the set value can be reduced appropriately. Too large a number will slow the response and may cause oscillations. The smaller the value, the higher the cutoff frequency and the faster the velocity feedback response. If a higher speed response is required, the set value can be reduced appropriately.
(6) Maximum output torque setting
Set the internal torque limit of the servo drive. The set value is the percentage of the rated torque. At any time, this limit is effective for positioning the complete pulse range under the set position control mode. This parameter provides the basis for the driver to judge whether the positioning is complete under the position control mode. When the number of remaining pulses in the position deviation counter is less than or equal to the value set by this parameter, the driver considers that the positioning has been completed, and the switch signal in place is ON, otherwise it is OFF.
In the position control mode, the output position positioning completion signal, acceleration and deceleration time constant is set to represent the motor acceleration time from 0 to 2000r/min or deceleration time from 2000 to 0r/min. Acceleration and deceleration characteristics are linear arrival speed range set arrival speed in non-position control mode, if the speed of the servo motor exceeds this set value, the speed arrival switch signal is ON, otherwise it is OFF. In position control mode, this parameter is not used. It doesn't matter the direction of rotation.
(7) Manually adjust the gain parameters
Adjust the speed proportional gain KVP value. When the servo system is installed, the parameters must be adjusted to make the system rotate stably. First adjust the speed proportional gain KVP value. Before adjustment, the integral gain KVI and differential gain KVD must be adjusted to zero, and then the KVP value is gradually increased; At the same time, observe whether there is sufficient oscillation when the servo motor stops, and adjust the KVP parameters manually to observe whether the rotation speed obviously rises and falls. When the KVP value is increased to the above phenomenon, the KVP value must be reduced back to make the oscillation eliminated and the rotation speed stable. At this time, the KVP value is the parameter value preliminarily determined. If necessary, after KⅥ and KVD adjustment, can be repeated correction to achieve the ideal value.
Adjust the value of integral gain KⅥ. Gradually increase the integral gain KVI value, so that the integral effect is gradually generated. As can be seen from the above introduction to integral control, when KVP value is increased to the critical value, it will produce oscillation and instability. Just like KVP value, KVI value will be reduced back to make the oscillation eliminated and the rotation velocity stable. At this time, KVI value is preliminarily determined parameter value.
Adjust the differential gain KVD value. The main purpose of differential gain is to make the velocity rotate smoothly and reduce the overshoot. Therefore, increasing the KVD value gradually can improve the velocity stability.
Adjust the position proportional gain KPP value. If the KPP value is adjusted too much, the motor positioning overshoot will be too large when the servo motor positioning, resulting in instability. At this time, the KPP value must be reduced to reduce the overshoot and avoid the instability area. However, it can not be adjusted too small to reduce the positioning efficiency. Therefore, the adjustment should be carefully matched.
(8) Automatic adjustment of gain parameters
Modern servo drives are microcomputerized, and most of them offer autogain tuning functions to handle most load conditions. When adjusting parameters, you can use the automatic parameter adjustment function first, and then manually adjust the parameters when necessary.
In fact, automatic gain adjustment also has option Settings, generally divided into several levels of control response, such as high response, medium response, low response, users can set according to the actual needs.