Appendix 4 Pid; Pid Control - Mitsubishi Electric MELSEC iQ-R Series User Manual

Appendix 4
This section describes PID.

PID control

This section describes the PID control of the temperature control module.
PID control system
The following figure shows a system for executing the PID control.
Temperature control module
Set value
(SV)
Set value data
storage area
Temperature
process
Temperature
value (PV)
process value
data storage area
PID control procedure
The PID control is executed in the following procedure:
Read the temperature
process value (PV)
Perform PID operation
Output the manipulated
value (MV)
PID control (simple two-degree-of-freedom)
The temperature control module operates in "simple two-degree-of-freedom." In the simple two-degree-of-freedom PID
control, the parameters of the two-degree-of-freedom PID control are simplified and used for control.
In the simple two-degree-of-freedom PID control, the module controls target objects using not only PID constants but also a
control response parameter. The parameter can be set to "fast," "normal," or "slow."
This setting can change the form of "response to the change of the set value (SV)" maintaining "response to the disturbance"
in a good condition. ( Page 56 Simple Two-degree-of-freedom)
Fast
Set value
(SV)
Response to the change
of the set value (SV)
The following describes the difference between the one-degree-of-freedom PID control, two-degree-of-freedom PID control,
and simple two-degree-of-freedom.
PID
PID operation
Manipulated
value (MV)
Import a signal from the temperature sensor and write it to the temperature
process value data storage area as a temperature process value (PV).
Perform PID operation using the Set value (SV)/temperature process
value (PV) values in the set value/temperature process value data
storage area.
Convert manipulated value (MV) obtained by the PID operation to
transistor-output on time and output it.
Normal
Set value
(SV)
Slow
Manipulated
Controlled
value data
object
storage area
Temperature
sensor
Response to the disturbance
A
APPX
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Appendix 4 PID