Mitsubishi Electric FR-A800 Series Instruction Manual page 605

 PID action
PID action is a combination of PI and PD action, which enables control that incorporates the respective strengths of these
actions.
Set point
Measured value
P action
I action
D action
PID action
(Note) PID action is the result of all P, I and D actions being added together.
 Reverse action
When deviation X = (set point - measured value) is a plus value, the manipulated amount (output frequency) is increased, and
when the deviation is a minus value, the manipulated amount is decreased.
 Forward action
When deviation X = (set point - measured value) is a minus value, the manipulated amount (output frequency) is increased,
and when the deviation is a plus value, the manipulated amount is decreased.
Relationship between deviation and manipulated amount (output frequency)
PID action setting
Reverse action
Forward action
604
5. PARAMETERS
5.14 (A) Application parameters
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Deviation
Time
Time
Time
2
y = at + bt + c
Time
[Heating]
+ X>0
Cold
Set
Hot
X<0
point
-
Feedback signal
(measured value)
[Cooling]
X>0
+
Too cold
Set
Hot
X<0
point
-
Feedback signal
(measured value)
Deviation
Plus Minus
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Deviation
Increase
Decrease
Measured value
Measured value
Decrease
Increase
Deviation
Set point
Set point