ABB ACQ810 - Page 178

178 Parameters
23.03 Derivation time Defines the derivation time of the speed controller.
Derivative action boosts the controller output if the error
value changes. The longer the derivation time, the more the
speed controller output is boosted during the change. If the
derivation time is set to zero, the controller works as a PI
controller, otherwise as a PID controller. The derivation
makes the control more responsive for disturbances.
The speed error derivative must be filtered with a low pass
filter to eliminate disturbances.
The figure below shows the speed controller output after an
error step when the error remains constant.
0.000 … 10.000 s Derivation time for speed controller. 1000 = 1 s
23.04 Deriv filt time Defines the derivation filter time constant. See parameter
23.03 Derivation time.
0.0 … 1000.0 ms Derivation filter time constant. 10 = 1 ms
No. Name/Value Description FbEq
Gain = K
p
= 1
T
I
= Integration time > 0
T
D
= Derivation time > 0
T
s
= Sample time period = 250 µs
Δe = Error value change between two samples
K
p
× T
D
×
Δe
T
s
Controller output
e = Error value
Error value
Time
T
I
K
p
×e
K
p
×e
%