
178 Parameters
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 a pulse encoder), derivative time is not normally
required and should be left at zero.
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 s
0.000…10.000 s
Derivation time for speed controller.
1000 = 1 s
Defines the derivation filter time constant. See parameter
8 ms
0…10000 ms
Derivation filter time constant.
1 = 1 ms
No.
Name/Value
Description
Default
FbEq 16
Gain = K
p
= 1
T
I
= Integration time > 0
T
D
= Derivation time > 0
T
s
= Sample time period = 250 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
K
p
× e
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ACS180 FW.book Page 178 Tuesday, March 9, 2021 2:25 PM