Glossary · Motion control and drives
Velocity loop
Also known as: Speed loop, Speed control loop
German: Drehzahlregelkreis
In drive control, the velocity loop is the middle loop of a cascaded drive control that compares commanded and measured speed and outputs a current (torque) setpoint to the current loop.
- Motion control
In one sentence
The velocity loop compares commanded and actual speed and outputs a torque setpoint; it sits between position and current loop.
Example
Raising the velocity loop gain made the spindle hold speed better under load, but too much gain caused audible oscillation.
How it applies
- Engineering: Velocity feedback comes from the encoder; filters on the speed signal reduce noise but add delay.
- Commissioning: The velocity loop is tuned after the current loop; the load inertia ratio strongly affects the right gains. Autotuning functions help but need checking.
- Operation: Changes of load inertia, for example different formats, can require different tuning sets.
- Documentation: In commissioning guides, describe the tuning order and the parameters involved. Note that changing loop parameters affects stopping behavior and should be done only by qualified personnel.
Velocity loop vs. speed control without feedback
Simple V/f drives control speed without measuring it; speed varies with load. A velocity loop measures speed and corrects deviations.