How to set the servo drive _ servo drive parameter setting steps (KNDSD100 detailed explanation)

In automation equipment, servo motors are often used, especially position control. Most of the brand's servo motors have position control functions. The controller sends out pulses to control the servo motor operation. The number of pulses corresponds to the angle of rotation, and the pulse frequency corresponds to the speed. (Related to the electronic gear setting), when a new system, the parameters can not work, first set the position gain, to ensure that the motor is no noise, try to set the larger, the moment of inertia ratio is also very important, can be set by self-learning Set the number to reference, then set the speed gain and speed integration time to ensure continuous operation at low speed and positional accuracy.

1. Position proportional gain: Set the proportional gain of the position loop regulator. The larger the setting value, the higher the gain and the greater the stiffness. Under the same frequency command pulse condition, the position lag is smaller. However, too large a value may cause oscillation or overshoot. The parameter values ​​are determined by the specific servo system model and load conditions.

2. Position feed forward gain: Set the feed forward gain of the position loop. The larger the set value, the smaller the position lag is at the command pulse of any frequency, and the feedforward gain of the position loop is large, and the high-speed response characteristic of the control system is improved, but the position of the system is unstable and oscillation is likely to occur. When high response characteristics are not required, this parameter is usually set to 0 to indicate the range: 0~100%

3. Speed ​​proportional gain: Set the proportional gain of the speed regulator. The larger the setting, the higher the gain and the greater the stiffness. The parameter values ​​are determined according to the specific servo drive system model and load value. In general, the larger the load inertia, the larger the set value. Set the larger value as much as possible without oscillating the system.

4. Speed ​​integral time constant: Set the integral time constant of the speed regulator. The smaller the setting value, the faster the integration speed. The parameter values ​​are determined according to the specific servo drive system model and load conditions. In general, the larger the load inertia, the larger the set value. Set the smaller value as much as possible without oscillating the system.

5. Speed ​​feedback filter factor: Set the speed feedback low-pass filter characteristics. The larger the value, the lower the cutoff frequency and the less noise the motor produces. If the load inertia is large, the set value can be appropriately reduced. The value is too large, causing the response to slow down and may cause oscillation. The smaller the value, the higher the cutoff frequency and the faster the speed feedback response. If a higher speed response is required, the set value can be appropriately reduced.

6. Maximum output torque setting: Set the internal torque limit value of the servo drive. The set value is a percentage of the rated torque. At any time, this limit is valid. The positioning is completed. The range is set to the position control mode. This parameter provides the basis for the drive to judge whether the positioning is completed under the position control mode. When the number of remaining pulses in the position deviation counter is less than or equal to the set value of this parameter, the drive considers that the positioning is completed, the in-position switch signal is ON, otherwise it is OFF. .

In the position control mode, the output position positioning completion signal is output, and the acceleration/deceleration time constant setting value indicates the acceleration time of the motor from 0 to 2000 r/min or the deceleration time from 2000 to 0 r/min. The acceleration/deceleration characteristic is a linear arrival speed range setting arrival speed. In the non-position control mode, if the servo motor speed exceeds the set value, the speed arrival switch signal is ON, otherwise it is OFF. In the position control mode, this parameter is not used. Independent of the direction of rotation.

7, manually adjust the gain parameters

Adjust the speed proportional gain KVP value. After 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 the adjustment, the integral gain KVI and the differential gain KVD must be adjusted to zero, and then the KVP value is gradually increased. At the same time, observe whether the servo motor stops when it stops, and manually adjust the KVP parameter to observe whether the rotation speed is obviously fast or not. SLOW. When the KVP value is increased to the above phenomenon, the KVP value must be adjusted back to small, so that the oscillation is eliminated and the rotation speed is stable. The KVP value at this time is the initially determined parameter value. If necessary, after KVI and KVD adjustment, you can make repeated corrections to achieve the desired value.

Adjust the integral gain KVI value. The integral gain KVI value is gradually increased, so that the integral effect is gradually generated. It can be seen from the introduction of the integral control that the KVP value and the integral effect increase to the critical value will cause oscillation and instability. Like the KVP value, the KVI value is adjusted back to small, so that the oscillation is eliminated and the rotation speed is stable. The KVI value at this time is the initially determined parameter value.

Adjust the differential gain KVD value. The main purpose of differential gain is to make the speed rotate smoothly and reduce the overshoot. Therefore, increasing the KVD value gradually improves the speed stability.

Adjust the position proportional gain KPP value. If the KPP value is adjusted too large, the motor positioning overshoot will be too large when the servo motor is positioned, causing instability. At this time, it is necessary to reduce the KPP value, reduce the overshoot and avoid the unstable region; but it cannot be adjusted too small to reduce the positioning efficiency. Therefore, care should be taken when adjusting.

8, automatically adjust the gain parameters

Modern servo drives are micro-computerized, and most provide automatic gain tuning to handle most load conditions. In the parameter adjustment, you can use the automatic parameter adjustment function first, and then manually adjust if necessary.

In fact, the automatic gain adjustment also has an option setting. Generally, the control response is divided into several levels, such as high response, medium response, and low response, and the user can set according to actual needs.

1.1, basic functions

The SD100 adopts the internationally advanced digital signal processor (DSP) TM320 (S240), large-scale programmable gate array (FPGA), and Mitsubishi's new generation intelligent power module (1PM). It has high integration, small size and overspeed. Protection functions such as overcurrent, overload, main power overvoltage and undervoltage, encoder abnormality and position tolerance.

Compared with the stepping motor, the AC servo motor has no step-out phenomenon. The servo motor has its own encoder, the position signal is fed back to the servo drive, and together with the open-loop position controller constitutes a semi-closed loop control system. The speed ratio is 1:5000, the torque is constant, and the torques of 1 r and 2000 r are basically the same. From low speed to high speed, it has stable torque characteristics and fast response characteristics. With full digital control, control is simple and flexible. The user can make appropriate settings for the working mode and running characteristics of the servo through parameter modification. The current price is only 2,000 to 3,000 yuan higher than the stepper motor.

1.2, parameter adjustment

The SD100 provides users with a wide range of user parameters from 0 to 59, alarm parameters from 1 to 32, and monitoring methods (motor speed, position deviation, etc.) of 22. Users can adjust the parameters according to different site conditions to achieve the best control effect. The meaning of several commonly used parameters is:

(1) “0” is the password parameter, the factory value is 315. If the user changes the model, the password must be changed to 385.

(2) “1” is the model code, which corresponds to the drive and motor of different power levels in the same series.

(3) "4" is the control mode selection. Change this parameter to set the control mode of the drive. Among them, “0” is the position control mode; “1” is the speed control mode; “2” is the trial operation control mode; “3” is the JOG control mode; “4” is the encoder zero adjustment mode; “5” is the open mode; Ring control mode (user test voltage and encoder); "6" is the torque control mode.

(4) "5" is the speed proportional gain, and the factory value is 150. The larger the setting, the higher the gain and the higher the stiffness. The parameter settings are set according to the specific servo drive model and load conditions. In general, the larger the load inertia, the larger the set value. When the system does not oscillate, try to set it larger.

(5) "6" is the speed integral time constant, and the factory default is 20. The smaller the setting, the faster the integration speed, too small for overshoot, and too large for slow response. The parameter settings are determined by the specific servo drive model and load. In general, the larger the load inertia, the larger the set value.

(6) "40" and "4l" are acceleration/deceleration time constants, and the factory setting is 0. This setting indicates the acceleration time or deceleration time required for the motor to rotate from 0 to 100 r/min. The acceleration and deceleration characteristics are linear.

(7) "9" is the position proportional gain, and the factory is not set to 40. The larger the setting value is, the higher the gain is, the higher the stiffness is, and the smaller the position lag is under the same frequency command pulse condition. However, too large a value may cause oscillation or overshoot. The parameter values ​​are based on the specific servo drive model and load conditions.

When the SD100 servo drive is matched with the Kanedi CNC system, only the parameters in Table 1 need to be set. The remaining parameters are generally not modified.

The setting of the electronic gear ratio is as follows: With the KND-SD100 servo drive, the electronic gear ratio of the KND system should be set to CMR/CMD=1:1. KND-SD100 servo drive electronic gear ratio is set to

Position command pulse frequency division numerator (PA12) / position command pulse frequency division denominator (PA13) = 4 × 2500 (encoder stripe number) / pulley ratio × screw pitch × 1000

The numerator and denominator can be approximated as an integer.

For a lathe, if the X axis is programmed with a diameter, the denominator of the above formula should be multiplied by 2, ie:

Position command pulse frequency division numerator (PA12) / position command pulse frequency division denominator (PA13) = 4 × 2500 (encoder stripe number) / pulley ratio × screw pitch × 1000 × 2

Example: X-axis screw pitch is 4mm, 1:1 transmission; Z-axis screw pitch is 6mm, 1:2 reduction drive, the electronic gear ratio of the X-axis drive is

PA12/PA13=4×2500/(1×4×1000×2)=5/4.

The electronic gear ratio of the Z-axis drive is

PA12/PA13=4×2500/(6×1000×1/2) (reduction gear ratio)=10/3

Therefore, for an X-axis drive, PA/2/PA/3 should be set to 5/4, and for a Z-axis drive, PA12/PA13 should be set to 10/3.

(1) After setting the parameters of the SD100 servo driver according to the above, start to optimize the adjustment of the servo performance, that is, the adjustment of the drive gain parameter. Generally, the SD100 driver maintains the default gain parameters, which can basically meet the processing requirements of users. When the motor is running at the default gain, if the motor makes an abnormal sound, first consider whether there is a problem with the motor shaft installation. After checking the problem, consider the method of resonance suppression, modify parameter No. 7 (torque filter) and parameter No. 8 (speed detection low-pass filter) to suppress the vibration generated by the motor. The default parameter of parameters 7 and 8 is 100. Try reducing the parameters of parameters 7 and 8 by 10 each time and press the confirm key. Run the motor, if it is not normal, reduce it by 10 until the motor has no abnormal sound. Generally, the adjustment range of parameters No. 7 and No. 8 is between 20 and 80, so that the resonance suppression effect can be basically achieved.

(2) When the factory parameters are maintained, the machining effect is not achieved. For example, the rake roughness value of the lathe is large. Try to adjust the following parameters: 1 speed proportional gain PA5 adjustment: confirm the normal start of the drive, manually control with the numerical control system Motor rotation (machine movement). Make sure to adjust this parameter if the motor does not vibrate. The larger the set value, the greater the rigidity, the higher the positioning accuracy of the machine tool. Each time the value is increased by 5 until the vibration is generated. After the value is reduced to stabilize, the value is reduced by 10; 2 position proportional gain PA9: In the stable range, try to set it larger, so that the machine tracking characteristics are good and the hysteresis error is small. Similar to the speed proportional gain adjustment, this value should be adjusted as much as possible without generating vibration; 3 if the above two parameters are not improved, the machining effect can not be achieved, and the parameters of parameters 7 and 8 can be used for vibration. Suppress parameter adjustment. After the adjustment, the parameters of the 5th and 9th drives can be adjusted upwards, which should meet the processing requirements of the user.

Once an alarm signal occurs, the SERVOPACK will disable the motor and adjust the user parameters until the power is turned off. The user can judge the type of the fault and the cause of the fault based on the displayed alarm information. Refer to the SD100 User Manual for specific troubleshooting methods. If there are no alarms, then it is naturally a drive failure. Of course, it is also possible that the servo has no fault at all, but the control signal or the host computer has a problem that causes the servo to not operate.

In addition to looking at the error, alarm number on the drive, check the manual, sometimes the most direct judgment is interchange, such as the X-axis and Z-axis interchange of the CNC lathe (the same model can be used). Or in the case that the servo motor power gap is not large, modify some characteristic parameters of the servo drive (such as the "1" model code parameter of KNDSD100), exchange them in a short time, and then change it back after determining the fault.

It is also possible to modify the numerical control system parameters, lock an axis such as the X axis, and prevent the system from detecting the X axis to achieve the purpose of judgment. However, it should be noted that the X-axis and the Z-axis are interchangeable, and even if the models are the same, the machine may have problems due to different loads and different parameters. Before confirming the inspection plan, you must consider comprehensiveness to avoid unnecessary losses.

Furthermore, since the AC servo unit usually uses a unified power supply system of the numerical control system, the voltage of the three-phase AC 220 V comes from the servo transformer. Therefore, the operation specifications must be met during the operation. For example: U, V, W three-phase output must be connected in the correct order, otherwise the motor will not operate normally, will give an alarm signal, and prohibit the motor from running.