Pid Control - Mitsubishi Electric 800 Series Instruction Manual

14.4

PID control

Process control such as flow rate, air volume or pressure are possible on the inverter.
A feedback system can be configured and PID control can be performed with the set point and feed back values set by analog
input signals (terminals 2 and 4) or using parameter values given via communication or by the PLC function.
Pr. Name
127 PID control automatic
A612 switchover frequency
128
PID action selection
A610
129
PID proportional band
A613
130
PID integral time
A614
131
PID upper limit
A601
132
PID lower limit
A602
133
PID action set point
A611
134
PID differential time
A615
553
PID deviation limit
A603
554 PID signal operation
A604 selection
575 Output interruption
A621 detection time
576 Output interruption
A622 detection level
577 Output interruption
A623 cancel level
609 PID set point/deviation
A624 input selection
Initial value Setting range
0 to 590 Hz
9999
9999
0, 20, 21, 50, 51,
60, 61, 1000,
1001, 1010,
0
1011, 2000,
2001, 2010, 2011
40 to 43
0.1% to 1000%
100%
9999
0.1 to 3600 s
1 s
9999
0% to 100%
9999
9999
0% to 100%
9999
9999
0% to 100%
9999
9999
0.01 to 10 s
9999
9999
0% to 100%
9999
9999
0 0 to 3, 10 to 13
0 to 3600 s
1 s
9999
0 Hz 0 to 590 Hz
1000% 900% to 1100%
2
3
2
4
5
Description
Set the value at which control is automatically switched to PID
control.
No PID control automatic switchover function
Select how to input the deviation value, measured value and set
point, and forward and reverse action.
Refer to page 355.
If a narrow proportional band is set (small parameter setting value),
the manipulated amount changes considerably by slight changes in
the measured value. As a result, response improves as the
proportional band becomes narrower, though stability worsens as
shown by the occurrence of hunting. Gain Kp=1/proportional band
No proportional control
With deviation step input, this is the time (Ti) used for obtaining the
same manipulated amount as proportional band (P) by only integral
(I) action. Arrival to the set point becomes quicker the shorter an
integral time is set, though hunting is more likely to occur.
No integral control
Set the upper limit. The FUP signal is output when the feedback
value exceeds this setting. The maximum input (20 mA/5 V/10 V) of
the measured value is equivalent to 100%.
No function
Set the lower limit. The FDN signal is output when the measured
value falls below the setting range. The maximum input (20 mA/5 V/
10 V) of the measured value is equivalent to 100%.
No function
Set the set point during PID control.
Set point set by Pr.128.
With deviation ramp input, this is the time (Td) used for obtaining the
manipulated amount only by proportional action (P). Response to
changes in deviation increase greatly as the differential time
increases.
No differential control
The Y48 signal is output when the absolute value of the deviation
exceeds the deviation limit value.
No function
The action when the upper or lower limit for a measured value input
is detected or when a limit for the deviation is detected can be
selected. The operation for PID output suspension function can be
selected.
When the output frequency after PID calculation stays less than the
Pr.576 setting for the time set in Pr.575 or more, the inverter
operation is suspended.
No output interruption function
Set the frequency at which output interruption is performed.
Level at which the PID output suspension function is released. Set
"Pr.577 - 1000%".
The set point or deviation value is input through terminal 2.
The set point or deviation value is input through terminal 4.
The set point or deviation value is input via communication.
The set point or deviation value is input by the PLC function.
14.(A) Application Parameters
14.4 PID control
11
12
13
14
15
16
17
18
19
20
339