Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 261)

Rockwell Automation Publication 750-RM002B-EN-P - September 2013 261
Motor Control Chapter 4
Speed Loop Damping - P653 [Spd Loop Damping]
Sets the damping factor of the vector speed loop’s characteristic equation.
Damping affects the integral gain when a non-zero bandwidth has been entered.
A damping factor of 1.0 is considered critical damping. Lowering the damping
produces faster load disturbance rejection, but can cause a more oscillatory
response. When the speed regulator bandwidth is zero, gains are set manually and
damping factor has no effect.
Integral Gain - P647 [Speed Reg Ki]
Sets the integral gain of the speed regulator (in FV Motor Control modes). This
value is automatically calculated based on the bandwidth setting in P636 [Speed
Reg BW], P645 [Speed Reg Kp] and P653 [Spd Loop Damping]. Integral gain
can be manually adjusted by setting P636 [Speed Reg BW] to a value of zero.
Integral gain has effective scaling of (per unit torque/sec) / (per unit speed).
Proportional Gain - P645 [Speed Reg Kp]
This value is automatically calculated based on the bandwidth setting in P636
[Speed Reg BW] and P76 [Total Inertia]. The proportional gain can be manually
adjusted by setting P636 [Speed Reg BW] to a value of zero. Proportional gain
has effective scaling of (per unit torque) / (per unit speed). The maximum
allowable value of this parameter is limited by P76 [Total Inertia] and P646 [Spd
Reg Max Kp].
Feed Forward Gain - P643 [SpeedReg AntiBckup]
Controls over-shoot/under-shoot in the step response of the Vector Control
mode speed regulator. Over-shoot/under-shoot can be effectively eliminated
with a setting of 0.3, which removes backup of the motor shaft when zero speed is
reached. This parameter has no affect on the drive's response to load changes. A
value of zero disables this feature.
Servo Lock Gain - P642 [Servo Lock Gain] (PowerFlex 755 only)
Sets the gain of an additional integrator in the Vector Control mode speed
regulator. The effect of Servo Lock is to increase stiffness of the speed response to
a load disturbance. It behaves like a position regulator with velocity feed forward,
but without the pulse accuracy of a true position regulator. Gain is normally set
to less than 1/3 speed regulator bandwidth, or for the desired response. A value of
zero disables this feature.