ABB ACH550-UH HVAC, User Manual

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ACH550-UH User’s Manual 1-123
Parameters
Group 23: SPEED CONTROL
This group defines variables used for speed control operation.
Group 23: Speed Control
Code Description Range Resolution Default S
2301 PROP GAIN 0.00…200.00 0.01 3.00
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 the proportional
gain.
2302 INTEGRATION TIME 0.00…600.00 s 0.01 s 0.50 s
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 the integration time.
2303 DERIVATION TIME 0…10000 ms 1 ms 0 ms
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
Error value
Controller output
%
e = Error value
t
Controller
output =
K
p
· e
T
I
Controller output
%
Gain = K
p
= 1
T
I
= Integration time > 0
T
D
= Derivation time = 0
K
p
· e
e = Error value
K
p
· e
t
Gain = K
p
= 1
T
I
= Integration time > 0
T
D
= Derivation time > 0
T
s
= Sample time period = 2 ms
Δ
e = Error value change between two samples
T
I
K
p
· e
Error value
Controller output
%
e = Error value
K
p
· T
D
·
Δ
e
T
s
K
p
· e
t