Danfoss VLT Micro Drive FC 51 Design Manual page 21

Introduction to VLT® Micro ...
3.1.4 Reference Handling
Details for Open Loop and Closed Loop operation.
3 3
Intern resource
Preset relative reference
±100%
Preset reference 0 ±100%
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%
Extern resource 1
No function
Analog reference
±200 %
Local bus reference
±200 %
LCP potmeter 0~100 %
Extern resource 2
No function
Analog reference
±200 %
Local bus reference
±200 %
LCP potmeter 0~100 %
Extern resource 3
No function
Analog reference
±200 %
Local bus reference
±200 %
LCP potmeter 0~100 %
Illustration 3.4 Block Diagram Showing Remote Reference
The remote reference is comprised 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 one of the 3 Reference Source parameters
(3-15 Reference 1 Source, 3-16 Reference 2 Source and
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 two can be selected to be the active
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®
VLT Micro Drive FC 51 Design Guide
Relative scalling reference
Input command:
preset ref bit0, bit1, bit2
Preset reference
±100%
Y
Relative
reference
=
X
+ X+X*Y/100
Parameter choise:
Reference resource 1,2,3
±200%
+
±200%
External reference in %
MG02K202 - VLT
Input command:
freeze reference
maxRefPCT
±200%
minRefPct
min-max ref
±100%
Freeze
reference &
increase/
decrease
reference
Input commands:
Speed up/speed down
reference. Finally, this reference can by be scaled using
3-14 Preset Relative Reference.
The scaled reference is calculated as follows:
Reference = X + X ×
Where X is the external reference, the preset reference or
the sum of these and Y is 3-14 Preset Relative Reference in
[%].
If Y, 3-14 Preset Relative Reference is set to 0%, the
reference will not be affected by the scaling.
®
is a registered Danfoss trademark
Speed open
loop
Configuration
Scale to
mode
Hz
Remote
reference/
setpoint
Process
control
Scale to
process
unit
±200%
Feedback
handling
Remote
reference in %
( )
Y
100