ABB ACS550-01 - Speed Control

ACS550 User’s Manual 97
Start-Up
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,
AUTOTUNE
RUN, to automatically set proportional gain.
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,
AUTOTUNE
RUN, to automatically set integration time.
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
p
= 1
T
I
= Integration time = 0
T
D
= Derivation time = 0
Controller
Error Value
Controller Output
t
%
e = Error value
output =
K
p
*
e
T
I
Controller Output
t
%
Gain = K
p
= 1
T
I
= Integration time > 0
T
D
= Derivation time = 0
K
p
*
e
e = Error value
K
p
*
e
Gain = K
p
= 1
T
I
= Integration time > 0
T
D
= Derivation time > 0
T
s
= Sample time period = 2 ms
∆e = Error value change between two samples
T
I
K
p
*
e
Error Value
Controller Output
t
%
e = Error value
K
p
*
T
D
*
∆e
T
s
K
p
*
e