ABB ACS800 Firmware Manual page 183

Index Name/Selection
23.02 INTEGRATION TIME
0.01 ... 999.97 s
23.03 DERIVATION TIME
0.0 ... 9999.8 ms
Description
Defines an integration time for the speed controller. The integration time
defines the rate at which the controller output changes when the error value is
constant. The shorter the integration time, the faster the continuous error value
is corrected. Too short an integration time makes the control unstable.
The figure below shows the speed controller output after an error step when
the error remains constant.
%
Controller Output
K · e
p
K · e
p
Integration time
Defines the derivation time for 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.
Note: Changing this parameter is recommended only if a pulse encoder is
used.
The figure below shows the speed controller output after an error step when
the error remains constant.
%
Δe
K · T ·
p
T
K · e
s
p
K · e
p
Derivation time value.
Gain = K = 1
p
T = Integration time > 0
I
T = Derivation time = 0
D
e = Error value
T
I
Gain = K = 1
p
T = Integration time > 0
I
T = Derivation time > 0
D
T = Sample time period = 1 ms
s
Δe = Error value change between
two samples
Controller Output
T
I
FbEq
t
10 ...
999970
Error Value
e = Error value
t
1 = 1 ms
Actual signals and parameters
183