ABB ACS850 series, Manual

Page: 178 / 370

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.
Note: Changing this parameter value is recommended only if
a pulse encoder is used.
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
Δ
e = Error value change between two samples
K
p
× T
D
×
Δ
e
T
s
Controller output
e = Error value
Error value
Time
T
I
K
p
× e
K
p
× e
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