ABB ACS350 User Manual page 190

190
Parameters – complete descriptions
Index Name/Selection
2302 INTEGRATION TIME
0.00...600.00 s
2303 DERIVATION TIME
0....10000 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
Note: For automatic setting of the integration time, use autotune run
(parameter 2305 AUTOTUNE RUN).
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.
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
Gain = K
T = Integration time > 0
I
T = Derivation time > 0
D
T = Sample time period = 2 ms
s
Δe = Error value change between two samples
Time
Gain = K
T = Integration time > 0
I
T = Derivation time = 0
D
e = Error value
T
I
%
T
I
= 1
p
= 1
p
t
Controller output
Error value
e = Error value
t
Def, FbEq
2.5
1 = 0.01 s
0
1 = 1 ms