ABB ACS860, Firmware Manual

Page: 170 / 438

170 Parameters
25.04 Speed 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. For simple applications
(especially those without an encoder), derivative time is not
normally required and should be left at zero.
The figure below shows the speed controller output after an
error step when the error remains constant. The speed error
derivative must be filtered with a low pass filter to eliminate
external disturbances. 0.000 s
0.000 … 10.000 s Derivation time for speed controller. 1000 = 1 s
25.05 Derivation filter time Defines the derivation filter time constant. See parameter
25.04 Speed derivation time .
8 ms
0…10000 ms Derivation filter time constant. 1 = 1 ms
No. Name/Value Description Def / FbEq16
K
p
× e
Gain = K
p
= 1
T
I
= Integration time > 0
T
D
= Derivation time > 0
T
s
= Sample time period = 500 µs

e = Error value change between two samples
K
p
× T
D
×

e
T
s
Controller output
e = Error value
Error value
Time
T
I
K
p
× e
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