Danfoss VLT FC 100 Series Programming Manual page 163

®
VLT HVAC Drive Programming Guide
20-84 On Reference Bandwidth
Range:
*
5% [0 - 200%]
3.18.7. 20-9* PID Controller
This group provides the ability to manually adjust this PID Controller. By adjusting the PID Controller parameters the control performance may be
improved. See section PID in the
20-91 PID Anti Windup
Option:
[0] Off
* On
[1]
20-93 PID Proportional Gain
Range:
*
0.50 [0.00 = Off - 10.00]
20-94 PID Integral Time
Range:
*
[0.01 - 10000.00 = Off s] The integrator adds over time (integrates) the error between the feedback and the setpoint reference. This is
20.00 s
20-95 PID Differentiation Time
Range:
*
0.0 s [0.00 = Off - 10.00 s]
Function:
When the difference between the feedback and the setpoint reference is less than the value of this parameter,
the frequency converter's display will show "Run on Reference". This status can be communicated externally by
programming the function of a digital output for
munications, the On Reference status bit of the frequency converter's Status Word will be high (1).
On Reference Bandwidth
The is calculated as a percentage of the setpoint reference.
VLT HVAC Drive Design Guide, MG.11.Bx.yy
Function:
Off
[0] causes the PID Controller to continue to integrate (add) the error between the feedback and setpoint
reference even though the frequency converter cannot adjust its output frequency to correct this error. In this
case, the integral term of the PID Controller may become quite large. When the PID Controller can again control
the frequency converter's output frequency, it may attempt to initially make a large change in the frequency
converter's output frequency. This should generally be avoided.
On [1] stops the PID Controller from integrating (adding) the error between the feedback and the setpoint
reference if it is not possible to adjust the output frequency of the frequency converter to correct the error. This
can occur when the frequency converter has reached its minimum or maximum output frequency or when the
frequency converter is stopped.
Function:
This parameter adjusts the output of the frequency converter's PID Controller based on the error between the
feedback and the setpoint reference. Quick PID Controller response is obtained when this value is large. However,
if too large a value is used, the frequency converter's output frequency may become unstable.
Function:
required to ensure that the error approaches zero. Quick frequency converter speed adjustment is obtained when
this value is small. However, if too small of a value is used, the frequency converter's output frequency may
become unstable.
Function:
The differentiator monitors the rate of change of the feedback. If the feedback is changing quickly, it will adjust
the output of the PID Controller to reduce the rate of change of the feedback. Quick PID Controller response is
obtained when this value is large. However, if too large of a value is used, the frequency converter's output
frequency may become unstable.
Differentiation time is useful is situations where extremely fast frequency converter response and precise speed
control are required. It can be difficult to adjust this for proper system control. Differentiation time is not com-
monly used in VLT HVAC Drive applications. Therefore, it is generally best to leave this parameter at 0 or OFF.
MG.11.C5.02 - VLT ® is a registered Danfoss trademark
Run on Reference/No Warning
for guidelines on adjusting the PID Controller parameters.
3. Parameter Description
[8]. In addition, for serial com-
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