Velocity controller

The velocity controller is a PI controller with feed forward.

The controller parameters can be found in the CoE directory:

Proportional component K_p: Parameter 80n3:12_hex "Velocity loop proportional gain"
Integral component T_i: Parameter 80n3:11_hex "Velocity loop integral time"
Parameter 80n3:13_hex „Velocity feed forward gain”

You can disable the velocity controller by setting the proportional component K_P to zero and the feed-forward factor to a value greater than zero.

Optimizing the velocity controller

The following instructions describe a practical procedure for optimizing the velocity controller.

Prerequisite: the motor channel has been fully configured in accordance with the chapter Quick start.

1. Ensure that the parameter 80n2:11 "Select info data 1" is set to 7 "Motor velocity". Observe the corresponding variable "Info data 1" in a Scope View.

2. Set the proportional component 80n3:12 "Velocity loop proportional gain" to 0.

The velocity controller is temporarily disabled.

3. Set the variable Velocity to half the nominal velocity of the roller motor.

4. Set parameter 80n3:13 "Velocity feed forward gain" so that the specified velocity is approximately reached.

5. Configure the integral component 80n3:11 "Velocity loop integral time" rather sluggish.

6. Increase the proportional component 80n3:12 "Velocity loop proportional gain" in steps of 10 until the "Motor Velocity" in the Scope View starts to oscillate.

7. Increase the integral component 80n3:13 "Velocity loop integral time" until the oscillation is sufficiently minimized.

8. Repeat the previous two points if necessary, as an increased integral component usually reduces the oscillation tendency.

9. Reduce the proportional component 80n3:12 "Velocity loop proportional gain" by 30 %. The 30 % serves as a control reserve.

If the velocity overshoots at the start, reduce 80n3:13: "Velocity feed forward gain".