ABB ACSM1 Firmware Manual page 137

28.04 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.
Δe
K × T ×
p D
T
s
Note: Changing this parameter value is recommended only if a pulse encoder is used.
0...10 s
28.05 DERIV FILT TIME
Defines the derivation filter time constant.
0...1000 ms
28.06 ACC COMPENSATION
Selects the source for the acceleration compensation torque.
The default value is P.3.7, ie, signal
ERROR firmware block.
Note: This parameter has been locked, ie, no user setting is possible.
Value pointer: Group and index
FW block: SPEED CONTROL
Gain = K
T = Integration time > 0
I
T = Derivation time > 0
D
T = Sample time period = 250 µs
s
e = Error value
Δe = Error value change between two samples
%
K × e
p
K × e
p
T
Derivation time for speed controller.
FW block: SPEED CONTROL
Derivation filter time constant.
FW block: SPEED CONTROL
3.07 ACC COMP
(see above)
= 1
p
Controller output
Error value
I
(see above)
(see above)
TORQ, which is the output of the
Parameters and firmware blocks
e = Error value
t
SPEED
137