348
Special operation and frequency control
4.25 Special operation and frequency control
4.25.1 PID control (Pr. 127 to Pr. 134, Pr. 575 to Pr. 577)
Purpose Parameter that must 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
348
Switch between the inverter operation and
commercial power-supply operation to operate.
Commercial power supply-
inverter switchover function
Pr. 135 to Pr. 139, Pr. 159 356
Increase speed when the load is light.
Load torque high speed
frequency control
Pr. 4, Pr. 5, Pr. 270 to Pr. 274 361
Frequency control appropriate for the load torque Droop control Pr. 286 to Pr. 288 363
Frequency setting by pulse train input Pulse train input Pr. 291, Pr. 384 to Pr. 386 365
Make the motor speed constant by encoder Encoder feedback control
Pr. 144, Pr. 285, Pr. 359,
Pr. 367 to Pr. 369
367
Traverse function Traverse function Pr. 592 to Pr. 597 369
Avoid overvoltage alarm due to regeneration by
automatic adjustment of output frequency
Regeneration avoidance
function
Pr. 882 to Pr. 886 371
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
Set the frequency at which the control is automatically
changed to PID control.
9999 Without PID automatic switchover function
128 PID action selection 10
10 PID reverse action
Deviation value signal input
(terminal 1 )
11 PID forward action
20 PID reverse action
Measured value (terminal 4 )
Set point (terminal 2 or Pr. 133)
21 PID forward action
50 PID reverse action
Deviation value signal input
(L
ONWORKS , CC-Link communication)
51 PID forward action
60 PID reverse action
Measured value, set point input
(L
ONWORKS , CC-Link communication)
61 PID forward action
70
*2 PID reverse action
Deviation value signal input
(PLC function)
71
*2 PID forward action
80
*2 PID reverse action
Measured value, set point input
(PLC function)
81
*2 PID forward action
90
*2 PID reverse action Deviation value signal input
(PLC function)
(Not reflected to the inverter frequency)
91
*2 PID forward action
100
*2 PID reverse action Measured value, set point input
(PLC function)
(Not reflected to the inverter frequency)
101
*2 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, e.g. 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
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