Danfoss VLT Series Design Manual page 31

®
VLT HVAC Drive Design Guide
The following parameters are relevant for a simple PID control application:
Parameter
Feedback 1 Source par. 20-00 Select the source for Feedback 1. This is most commonly an
Reference/Feed-
back Unit
PID Normal/Inverse
Control
PID Proportional
Gain
PID Integral Time
This table summarizes the parameters that are needed to set up the drive's Closed Loop Controller
when a single feedback signal with no conversion is compared to a single setpoint. This is the
most common type of Closed Loop Controller.
Description of function
analog input, but other sources are also available. Use the
scaling of this input to provide the appropriate values for this
signal. By default, Analog Input 54 is the default source for
Feedback 1.
par 20-12 Select the unit for the setpoint reference and feedback for
the drive's Closed Loop Controller. Note: Because a conver-
sion can be applied to the feedback signal before it is used
by the Closed Loop Controller, the Reference/Feedback Unit
(par. 20-12) may not be the same as the Feedback Source
Unit (par. 20-02, 20-05 and 20-08).
Normal
par. 20-81 Select
the feedback is greater than the setpoint reference. Select
Inverse
[1] if the motor's speed should increase when the
feedback is greater than the setpoint reference.
par. 20-93 This parameter adjusts the output of the drive's closed loop
controlled based on the error between the feedback and the
setpoint reference. Quick controller response is obtained
when this value is large. However, if too large of a value is
used, the drive's output frequency may become unstable.
par. 20-94 The integrator adds over time (integrates) the error between
the feedback and the setpoint reference. This is required to
ensure that the error approaches zero. Quick controller re-
sponse is obtained when this value is small. However, if too
small of a value is used, the drive's output frequency may
become unstable. A setting of 10000 s disables the integra-
tor.
®
MG.11.B2.02 - VLT is a registered Danfoss trademark
2. Introduction to VLT HVAC Drive
[0] if the motor's speed should decrease when
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