Special operation and frequency control
4.21 Special operation and frequency control
Perform process control such as
pump and air volume.
Avoid overvoltage alarm due to
regeneration by automatic
adjustment of output frequency
4.21.1 PID control (Pr. 127 to Pr. 134, Pr. 553, Pr. 554, Pr. 575 to Pr. 577, C42 to C45)
The inverter can be used to perform 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.
PID control automatic
PID action selection
PID proportional band
PID integral time
PID upper limit
PID lower limit
PID action set point
PID differential time
PID deviation limit
PID signal operation
Parameter that should be Set
0 to 400Hz Frequency at which the control is automatically changed to PID control.
Without PID automatic switchover function
PID action is not performed
PID reverse action
PID forward action
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
No proportional control
When deviation step is input, time (Ti) is the time required for integral (I)
action to provide the same manipulated variable as the proportional (P)
action. As the integral time decreases, the set point is reached earlier
but hunting occurs more easily.
No integral control.
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%.
If the measured 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%.
Used to set the set point for PID control.
Terminal 2 input is the set point.
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.
No differential control.
Y48 signal is output when the absolute value of deviation amount
exceeds the deviation limit value.
Select the operation to be performed at the detection of upper, lower,
0 to 3,
and deviation limit for the measured value input. The operation for PID
10 to 13
output suspension function can be selected.
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.
Without output interruption function
Set the frequency at which the output interruption processing is
0 to 400Hz
Set the level (Pr. 577 minus 1000%) at which the PID output interruption
function is canceled.
Pr. 127 to Pr. 134, Pr. 553, Pr. 554,
Pr. 575 to Pr. 577, C42 to C45
Pr. 882, Pr. 883, Pr. 885, Pr. 886
Measured value (terminal 4)
Set value (terminal 2 or Pr. 133)
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