HVAC Functions
18-20 | CFW501
18
18.7 EXTERNAL PID CONTROLLER
This parameter group allows the user to configure the External PID controller operation.
The External PID controller allows controlling an external actuator to the CFW501 frequency inverter via analog
output by comparing the process variable control (feedback) with the required setpoint.
The process variable is the one the PID controller uses as feedback of its control actions being compared to the
required control setpoint, thus generating the error for the control.
It is read via analog input; therefore, it will be necessary to configure which analog input will be the feedback for
the external PID controller.
Is adopted the "Academic" structure for the External PID controller, which obeys the following equation:
u(k) = i(k-1) + Kp ∙ [(1 + Ki ∙ Ts + (Kd/Ts)) ∙ e(k) - (Kd/Ts)) ∙ e(k-1)]
where:
u(k) = External PID controller output;
i(k-1) = Integral part of the previous instant;
Kp = Proportional gain;
Ki = Integral gain;
Kd = Derivative gain;
Ts = Sampling time;
e(k) = Error at the actual instant (control setpoint – process variable);
e(k-1) = Error at the previous instant.
P1060 – External PID Controller Automatic Setpoint
Adjustable
Range:
-32768 to 32767 Factory
Setting:
0
Properties:
Access groups
via HMI:
HVAC
Description:
This parameter defines the value of External PID controller setpoint in engineering unit when it is in automatic
mode.
NOTE!
This parameter will be viewed according to the selection of the parameters for the engineering unit
2 (P0512 and P0513).
P1061 – External PID Controller Manual Setpoint
Adjustable
Range:
0.0 to 100.0 % Factory
Setting:
0.0 %
Properties:
Access groups
via HMI:
HVAC
Description:
This parameter defines the value of External PID controller setpoint when it is in manual mode.
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