ABB ACS800 Series Firmware Manual page 98

86
No. Name/Value
23.02 INTEGRATION TIME
0.01...999.97 s
23.03 DERIVATION TIME
0.0...9999.8 ms
Actual signals and parameters
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
T
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 D
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 = 2 ms
s
Δe = Error value change between
two samples
Controller Output
Error Value
T
I
FbEq
1000 = 1 s
e = Error value
t
1 = 1 ms