ABB ACQ810 - Page 69

Program features 69
• 23.02 Integration time (integration time of the speed controller)
• 01.31 Mech time const (mechanical time constant of the machinery).
The figure below shows speed responses at a speed reference step (typically
1…20%).
The figure below is a simplified block diagram of the speed controller. The controller
output is the reference for the torque controller.
A: Undercompensated
B: Normally tuned (autotuning)
C: Normally tuned (manually). Better dynamic performance than with B
D: Overcompensated speed controller
%
t
n
C
B
D
n
N
A
Derivative
Proportional,
integral
Derivative
acceleration
compensation
Torque
reference
Speed
reference
Actual speed
Error
value
-
+
+
+
+