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5.20.2 PID control (Pr. 125, Pr. 127 to Pr. 132, Pr. 134, C2)
The inverter can be used to exercise process control, e.g. flow rate, air volume or pressure.
Use the value set in the CC-Link communication register (RWw9) as the set point, and the value set in the CC-Link
communication register (RWwA) as the feedback value. With these values, configure a feedback system and perform
PID control.
Parameter
Name
Number
PID control automatic
127
switchover frequency
128
PID action selection
129
PID proportional band
∗1
130
PID integral time
∗1
131
PID upper limit
132
PID lower limit
134
PID differential time
∗1
Frequency setting
125
gain
Frequency setting
C2
bias
The above parameters can be set when Pr. 160 User group read selection ="0". (Refer to page 197)
∗1
This parameter allows its setting to be changed during operation in any operation mode even if "0" (initial value) is set in Pr. 77 Parameter write selection.
(1)
PID control basic configuration
Pr. 128 = "50, 51" (measured value input)
Set point
To outside
Special operation and frequency control
Initial
Setting
Value
Range
0 to 400Hz Frequency at which the control is automatically changed to PID control.
9999
9999
Without PID automatic switchover function
0
PID action is not performed
20, 21,
For manufacturer setting. Do not set.
40 to 43
50
PID reverse action
0
51
PID forward action
60
PID reverse action
61
PID forward action
If the proportional band is narrow (parameter setting is small), the
manipulated variable varies greatly with a slight change of the
0.1 to
measured value. Hence, as the proportional band narrows, the
100%
1000%
response sensitivity (gain) improves but the stability deteriorates, e.g.
hunting occurs. Gain Kp= 1/proportional band
9999
No proportional control
When deviation step is input, time (Ti) is the time required for integral (I)
0.1 to
action to provide the same manipulated variable as the proportional (P)
1s
action. As the integral time decreases, the set point is reached earlier
3600s
but hunting occurs more easily.
9999
No integral control.
Maximum value
0 to
If the feedback value exceeds the setting, the FUP signal is output. The
9999
100%
maximum input of the measured value is equivalent to 100%.
9999
No function
Minimum frequency
0 to
If the process value falls below the setting range, the FDN signal is
9999
output. The maximum input of the measured value is equivalent to
100%
100%.
9999
No function
For deviation ramp input, time (Td) required for providing only the
0.01 to
manipulated variable for the proportional (P) action. As the differential
9999
10.00s
time increases, greater response is made to a deviation change.
9999
No differential control.
0 to
60Hz
Output frequency at 100% deviation input under PID control
400Hz
0 to
0Hz
Output frequency at 0% deviation input under PID control
400Hz
Inverter circuit
PID operation
Deviation signal
+ -
CC-Link
Kp 1+
communication
(RWwB)
(0 to 100%)
Feedback signal (measured value)
Kp: Proportionality constant Ti: Integral time S: Operator Td: Differential time
Description
Deviation value signal input (CC-Link
communication)
Measured value, set point input (CC-Link
communication)
Motor
Manipulated
variable
1
+Td
S
Ti
S
IM
203
5
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