Mitsubishi Electric FR-E800, Instruction Manual

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15. (A) Application Parameters
15.4 PID control
[Example of action when the measured value changes proportionately]
(Note) PD action is the result of P and D actions being added together.
 PID action
PID action is a combination of PI and PD action, which enables control that incorporates the respective strengths of these
actions.
(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
Deviation
Plus Minus
Reverse action
Forward action
Deviation
Set point
Measured value
Time
Time
Time
PD
action
D action
P action
Deviation
Set point
Measured value
Time
Time
Time
PID action
D action
P action
I action
Time
y = at
2
+ bt + c
Set
point
X>0
X<0
Feedback signal
(measured value)
+
-
[Heating]
Deviation
Set point
Measured value
Cold
Hot Increase
Decrease
Set
point
X>0
X<0
Feedback signal
(measured value)
+
-
[Cooling]
Deviation
Set point
Measured value
Too cold
Hot Decrease
Increase