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Special operation and frequency control
4.20 Special operation and frequency control
4.20.1 PID control (Pr. 127 to Pr. 134, Pr. 575 to Pr. 577)
Purpose Parameter that should be Set Refer to Page
Perform process control such as
pump and air volume.
PID control
Pr. 127 to Pr. 134, Pr. 575
to Pr. 577
212
Dancer control
PID control (dancer control
setting)
Pr. 44, Pr. 45, Pr. 128 to Pr. 134
220
Avoid overvoltage alarm due to
regeneration by automatic
adjustment of output frequency
Regeneration avoidance
function
Pr. 882, Pr. 883, Pr. 885, Pr. 886
226
The inverter can be used to exercise process control, e.g. flow rate, air volume or pressure.
The terminal 2 input signal or parameter setting is used as a set point and the terminal 4 input signal used as a
feedback value to constitute a feedback system for PID control.
Parameter
Number
Name
Initial
Value
Setting
Range
Description
127
PID control automatic
switchover frequency
9999
0 to 400Hz
Frequency at which the control is automatically changed to PID control.
9999 Without PID automatic switchover function
128 PID action selection
0
0 PID action is not performed
20 PID reverse action Measured value (terminal 4)
Set value (terminal 2 or Pr. 133)
21 PID forward action
40 PID reverse action
Addition
method: fixed
For dancer control
set point (Pr. 133),
measured value (terminal 4)
main speed (frequency command
of the operation mode)
41 PID forward action
42 PID reverse action
Addition
method: ratio
43 PID forward action
129 ∗1 PID proportional band
100%
0.1 to
1000%
If the proportional band is narrow (parameter setting is small), the
manipulated variable varies greatly with a slight change of the
measured value. Hence, as the proportional band narrows, the
response sensitivity (gain) improves but the stability deteriorates, for
example, hunting occurs. Gain Kp= 1/proportional band
9999 No proportional control
130 ∗1 PID integral time
1s
0.1 to
3600s
For deviation step input, time (Ti) required for only the integral (I) action
to provide the same manipulated variable as that for the proportional (P)
action. As the integral time decreases, the set point is reached earlier
but hunting occurs more easily.
9999 No integral control.
131 PID upper limit
9999
0 to
100%
Maximum value
If the feedback value exceeds the setting, the FUP signal is output. The
maximum input (20mA/5V/10V) of the measured value (terminal 4) is
equivalent to 100%.
9999 No function
132 PID lower limit
9999
0 to
100%
Minimum frequency
If the process value falls below the setting range, the FDN signal is
output. The maximum input (20mA/5V/10V) of the measured value
(terminal 4) is equivalent to 100%.
9999 No function
133 ∗1 PID action set point
9999
0 to 100%
Used to set the set point for PID control.
9999 Terminal 2 input is the set point.
134 ∗1 PID differential time
9999
0.01 to
10s
For deviation ramp input, time (Td) is required for providing only the
manipulated variable for the proportional (P) action. As the differential
time increases, greater response is made to a deviation change.
9999 No differential control.
575
Output interruption
detection time
1s
0 to
3600s
The inverter stops operation if the output frequency after PID operation
remains at less than the Pr. 576 setting for longer than the time set in Pr.
575.
9999 Without output interruption function
576
Output interruption
detection level
0Hz
0 to 400Hz
Set the frequency at which the output interruption processing is
performed.