ABB ACS550-02 User Manual page 103

Group 23: Speed Control
This group defines variables used for speed control operation.
Code Description
2301 PROP GAIN
Sets the relative gain for the speed controller.
• Larger values may cause speed oscillation.
• The figure shows the speed controller output
after an error step (error remains constant).
Note! You can use parameter 2305,
, to automatically set proportional gain.
RUN
2302 INTEGRATION TIME
Sets the integration time for the speed
controller.
• The integration time defines the rate at which
the controller output changes for a constant
error value.
• Shorter integration times correct continuous
errors faster.
• Control becomes unstable if the integration
time is too short.
• The figure shows the speed controller output
after an error step (error remains constant).
Note! You can use parameter 2305,
, to automatically set integration time.
RUN
2303 DERIVATION TIME
Sets the derivation time for the speed controller.
• Derivative action makes the control more responsive to 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 figure below shows the speed controller output after an error step when the error remains constant.
Gain = K = 1
p
T
= Integration time > 0
I
T = Derivation time > 0
D
T = Sample time period = 2 ms
s
∆e = Error value change between two samples
AUTOTUNE
Controller
output =
K
K
AUTOTUNE
%
∆e
K * T
*
p D
T
K * e
s
p
K * e
p
%
Error Value
Controller Output
K * e
p
Controller Output
%
* e
p
* e
p
T
T
I
Gain = K = 1
p
T = Integration time = 0
I
T = Derivation time = 0
D
e = Error value
Gain = K = 1
p
T = Integration time > 0
I
T = Derivation time = 0
D
e = Error value
t
I
Controller Output
Error Value
e = Error value
t
Start-Up
101
t