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
