Pid Control - Mitsubishi Electric 800 Series Instruction Manual

(A) Application parameters
5.14.10

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 using the terminal 2 input signal or parameter
setting value as the set point, and the terminal 4 input signal as the feedback value.
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
488
PARAMETERS
Initial
Setting range
value
0 to 590 Hz
9999
9999
0, 10, 11, 20, 21,
50, 51, 60, 61, 70,
71, 80, 81, 90, 91,
100, 101, 1000,
0
1001, 1010, 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%
Description
Set the value at which control is automatically switched to
PID control.
Without 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 508.
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
Without proportional band
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.
Without integral control
Sets 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 (terminal 4) 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 (terminal 4) 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.
Without 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.
If the status where the output frequency after PID
calculation is less than the Pr.576 setting is continuously the
Pr.575 set time or more, inverter running is suspended.
Without 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%".