Second Pid Function (Pr.753 To Pr. 758, Pr.765 To Pr.769) - Mitsubishi F700 Series Instruction Manual

4.20.4 Second PID function (Pr.753 to Pr. 758, Pr.765 to Pr.769)

When the RT signal is ON and Pr. 753 Second PID action selection  9999, PID control is commanded by the
second function parameters.
When Pr. 753 = 9999, normal PID control is performed even if the second functions are valid.
When the control method is switched from the second PID control to the normal PID control, the integral value is
estimated. The integral value is estimated by calculating the integral term with the output frequency and the P
term. This method is same as when the control method changes to PID control when the frequency reaches the
automatic switchover frequency.
Parameter
Name
Number
Second PID action
753
selection
Second PID control
754 automatic switchover
frequency
Second PID action set
755
*1
point
Second PID
756
*1
proportional band
Second PID integral
757
*1
time
Second PID differential
758
*1
time
Initial Setting
Value Range
10 , 110 PID reverse action
*2
11 , 111 PID forward action
*2
20 , 120 PID reverse action
*2
21 , 121 PID forward action
*2
40 , 140 PID reverse action
*2
41 , 141 PID forward action
*2
50 PID reverse action
*2
51 PID forward action
*2
60 PID reverse action
*2
61 PID forward action
*2
70 PID reverse action
*6
9999
71 PID forward action
*6
80 PID reverse action
*6
81 PID forward action
*6
90 PID reverse action
*6
91 PID forward action
*6
100 PID reverse action
*6
101 PID forward action
*6
Normal PID control is performed regardless of the second PID
9999
control parameter settings.
Set the frequency at which the control is automatically
0 to 400Hz
changed to PID control while the RT signals is ON.
9999
9999 Without second PID control automatic switchover function
Set the set point for PID control, which is performed while the
0 to 100%
*3
RT signal is ON.
9999
9999 Terminal 2 input is the set point while the RT signal is ON.
Set the proportional band for PID control, which is performed
while the RT signal is ON.
If the proportional band is narrow (parameter setting is small),
the manipulated variable varies greatly with a slight change of
0.1 to 1000%
the measured value. Hence, as the proportional band narrows,
100%
the response sensitivity (gain) improves but the stability
deteriorates, e.g. hunting occurs.
Gain Kp = 1/proportional band
9999 Without second proportional band
Set the PID integral time for PID control, which is performed
while the RT signal is ON.
When deviation step is input, time (Ti) is the time required for
0.1 to 3600s integral (I) action to provide the same manipulated variable as
1s
proportional (P) action.
As the integral time decreases, the set point is reached earlier
but hunting occurs more easily.
9999 Without second integral control
Set the PID differential time for PID control, which is performed
while the RT signal is ON.
0.01 to When deviation lamp is input, time (Td) is the time required to
9999 10.00s provide the manipulated variable of only the proportional (P)
action. As the differential time increases, greater response is
made to a deviation change.
9999 Without second differential control
PID control
Description
Deviation value signal input
(terminal 1 )
*4
Measured value (terminal 4
Set point (terminal 2 or Pr. 133)
*4
Measured value (terminal 4
Set point input (L W , CC-Link, BACnet)
ON ORKS
Deviation value signal input
(L W , CC-Link, BACnet)
ON ORKS
Measured value, set point input
(L W , CC-Link, BACnet)
ON ORKS
Deviation value signal input
(PLC function)
Measured value, set point input
(PLC function)
Deviation value signal input
(PLC function)
(Not reflected to the inverter frequency)
Measured value, set point input
(PLC function)
(Not reflected to the inverter frequency)
)
*5
)
*5
4
275