Rockwell Automation Publication 750-AT006D-EN-P - January 2022 61
Chapter 3 Out-of-Box Tuning
13. If necessary, reduce the acceleration and deceleration limits to meet application requirements and help protect the drive and motor
from overload.
a. For Velocity mode applications, reduce the velocity ramp acceleration and deceleration times in the velocity reference.
b. For Position mode applications, reduce the acceleration and deceleration times in the PTP planner.
c. As a last resort, reduce the acceleration limits in the velocity regulator. When Load Ratio = 0, these limits are set to their maximum
value, which provides the best performance for a motor under no-load conditions. However, the motor is loaded and may not be
able to accelerate as fast. As a result, you may have to reduce the acceleration and deceleration limits to meet application
requirements.
Single Knob Tuning
10:906 [System BW] can be used as a tuning knob when 10:905 [System C/U Select] = Calculated (0). Decreasing it stabilizes the system and
increasing it improves performance. The following parameters are automatically calculated as this parameter is adjusted.
10:1754 [c PReg Kp]
10:1756 [c PReg Ki]
10:1955 [c VReg Kp]
10:1957 [c VReg Ki]
10:2021 [c LdObs Kp]
10:2023 [c LdObs Ki]
10:2154 [c Trq LPF BW]
If 10:906 [System BW] is changed, adjust 10:2112 [Trq NF Freq LLim] to a value that is at least 2…3 times the value of 10:906 [System BW].
Encoderless Mode
: Alternate Feedback
If 10:1019 [Fb Loss Action] = Auto Tach SW (2), the parameter 10:1010 [Alt Fb GnScale] can be used as a single tuning knob to adjust the
system performance when the drive operates with the alternate feedback. The drive operates with the alternate feedback when a
feedback fault happens and the drive switches to the alternate feedback selected in 10:1006 [Alt VelFb Sel], which can be either an
encoder connected to an encoder module or the Open Loop Virtual Encoder.
To adjust the performance of the system with the alternate feedback, temporarily set 10:1019 [Fb Loss Action] = Alt Only (1) and adjust
10:1010 [Alt Fb GnScale] to the desired performance. After the performance with the alternate feedback is adjusted, set
10:1019 [Fb Loss Action] back to Auto Tach SW (2).
Is Further Tuning Required?
Here are some observations that indicate the drive is producing satisfactory performance without additional tuning:
• Visibly smooth non-oscillatory velocity feedback from a smooth cycle profile
• Little to no audible noise produced during and after a commanded motion
• Position and/or velocity errors are repeatable and within the application requirements
• The reference move type keeps the drive and motor within their thermal limits
If the load does not respond as intended, consider these factors before tuning:
• Investigate proper motor and drive sizing in Online Motion Analyzer. You may also want to compare various design options for gear
ratio, load size, coupling configuration, high versus low-resolution feedback devices, reference move types, and so on.
• Simulate the load in Online Motion Analyzer to conclude how the desired motion can be achieved. Problems are often minimized by
creating a more direct and stiff coupling between the motor and load. Quality mechanical components help to achieve this.
If the load requires additional tuning to optimize performance, continue on to Auto Tuning
on page 63. See Figure 60 for guidance on
progressing through the tuning process.
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