646
35 CPU MODULE BUILT-IN ANALOG FUNCTION
35.6 Function (PID Control Via Parameter)
■P control
P control is a control method that determines the output value (MV) in proportion to the deviation (E) between the temperature
process value (PV) and target value (SV).
When the value for the integral time (TI) and the differential time (TD) each is set to 0, P control is selected.
■P control (For standard PID control)
When the measured value (PV) = the target value (SV), the output value (MV) is 0%.
■P control (For heating-cooling PID control)
If 0 is set in the overlap/dead band settings when the measured value (PV) is equal to the target value (SV), both the output
value for heating (MVh) and the output value for cooling (MVc) are 0%.
■PI control
PI control is a control method that adds derivative control to P control to correct an offset (remaining deviation) that remains
when the temperature is stable. By setting the integral time (TI) properly, the process value (PV) and the target value (SV) can
be made to match when the temperature is stable.
When the value for the differential time (TD) is set to 0, PI control is selected.
• The value to be actually output is within the output limiter range set by the upper limit output limiter and lower limit output limiter.
• The proportional band (P) is the reciprocal of the proportional gain (KP).
• The value to be actually output is within the output limiter range set by the upper limit output limiter and lower limit output limiter.
• The heating proportional band (Ph) is the reciprocal of the heating proportional gain (KPh), and the cooling proportional band (Pc) is the reciprocal of the
cooling proportional gain (KPc).
100%
0%
Output value (MV)
Measured value (PV)
Target value (SV)
Target value (SV)
Proportional band (P)
100%
0%
Output value for heating
(MVh)
Output value for cooling
(MVc)
Measured value (PV)
Target value (SV)
Target value (SV)
Heating proportional band
(Ph)
Cooling proportional band
(Pc)
Measured value (PV)
Target value (SV)
Offset (remaining deviation)
P control
Time
PI control
To Next Page
Loading...
