Reference Handling - Danfoss VLT HVAC Basic Drive FC 101 Design Manual

Product Overview

3.2.6 Reference Handling

Details for open-loop and closed-loop operation.
Intern resource
Preset relative reference
±100%
Input command:
Preset reference 0 ±100%
preset ref bit0, bit1, bit2
Preset reference 1 ±100%
Preset reference 2 ±100%
Preset reference 3 ±100%
Preset reference 4 ±100%
Preset reference 5 ±100%
Preset reference 6 ±100%
Preset reference 7 ±100%
External resource 1
Parameter choise:
No function
Reference resource 1,2,3
Analog reference
±200 %
Local bus reference
±200 %
Pulse input reference
±200 %
+
External resource 2
No function
Analog reference
±200 %
Local bus reference
±200 %
Pulse input reference
±200 %
External resource 3
No function
Analog reference
±200 %
Local bus reference
±200 %
Pulse input reference
±200 %
Illustration 3.21 Block Diagram Showing Remote Reference
The remote reference consists of:
•
Preset references.
•
External references (analog inputs and serial
communication bus references).
•
The preset relative reference.
•
Feedback-controlled setpoint.
Up to 8 preset references can be programmed in the
frequency converter. The active preset reference can be
selected using digital inputs or the serial communications
bus. The reference can also be supplied externally, most
commonly from an analog input. This external source is
selected by 1 of the 3 reference source parameters
(parameter 3-15 Reference 1 Source,
parameter 3-16 Reference 2 Source, and
parameter 3-17 Reference 3 Source). All reference resources
and the bus reference are added to produce the total
external reference. The external reference, the preset
reference, or the sum of the 2 can be selected to be the
MG18C702
Design Guide
Relative scalling reference
Preset reference
±100%
Y
Relative
reference
=
X
±200%
+
X+X*Y/100
±200%
Input commands:
±200%
Speed up/speed down
External reference in %
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Input command:
mode
freeze reference
maxRefPCT
minRefPct
min-max ref
±100%
Freeze
reference &
increase/
decrease
reference
Remote
reference in %
active reference. Finally, this reference can by be scaled
using parameter 3-14 Preset Relative Reference.
The scaled reference is calculated as follows:
Y
Reference = X + X ×
100
Where X is the external reference, the preset reference or
the sum of these and Y is parameter 3-14 Preset Relative
Reference in [%].
If Y, parameter 3-14 Preset Relative Reference, is set to 0%,
the reference is not affected by the scaling.
3
Speed open
loop
Scale to
Hz
Remote
reference/
setpoint
Process
control
Scale to
process
unit
±200%
Feedback
handling
29
3