31
Service manual
Daikin R32 Rooftops UATYA-B
ESIE21-02 – 2021.03
3.8 Tips for PID controller setup
If temperature or humidity is managed using a PID controller, the controller parameters must be setup correctly for proper
operation. The controller is supplied with factory default parameters, which may require adjustment for adaptation to a spe
-
cific installation and peculiar work conditions.
Below is a list of the essential parameters for PID controller operation:
-
Kp = proportional coefficient;
-
Ki = integral coefficient;
-
Kd = derivative coefficient.
Proper selection of Kp, Ki, and Kd values enables having different PID controller configurations and different responses
from the controlled actuator, which are summarised in the table below.
Coef.
Control function
Main purpose
Coefficient effect on system
Increases
Decreases
Kp
A deviation of the controlled
value (error variation)
determines a variation of
the actuator output that is
proportional to the deviation
value.
The output must vary linearly,
according to the controlled
value.
Worsens system stability.
Improves system stability.
Speeds up system response.
Slows down system response.
Ki
A deviation of the controlled
value (error variation)
determines a variation of
the actuator output that is
proportional to the deviation
speed.
The control setpoint must be
achieved as quickly as possible,
thus cancelling the intrinsic
offset of the proportional
component.
Worsens system stability.
Improves system stability.
Speeds up system response.
Slows down system response.
Kd
A deviation of the controlled
value (error variation)
determines a variation of
the actuator output that is
proportional to the deviation
variation speed.
The system reaction time must
be reduced to go back to the
control setpoint.
Improves system stability.
Worsens system stability.
Slows down system response.
Speeds up system response.
Each action of the three components (proportional, integral and derivative) is limited by a minimum and a maximum value.
This is required so that, in specific transients, none of the three actions is neatly predominant over the others as this would
cause system instability.
Correct setup of the three coefficients and of the limit values of the related actions contributes to optimising the actuator
response to changes in the controlled value.
On the other hand, incorrect parameter setup may cause a worsened actuator response or instability in the system.
Our recommendation is as follows.
-
Change one coefficient at a time and check the effect of the change on the system after a certain amount of time (we
recommend after at least 10 minutes) in as stable as possible boundary conditions.
-
The value by which each parameter is changed (increased or reduced) must not exceed half the previous value. For
instance. The proportional coefficient Kp for temperature control is set to 500 and the system response needs to be
speeded up. The new Kp value must not exceed 750. If, on the other hand, the system response needs to be slowed
down for greater stability, the new Kp value must not be inferior to 250.
3 Software functions
Summary of Contents for UATYA-B
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