Danfoss VLT Micro Drive PK18 Design Manual page 21

Introduction to VLT Micro D...
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 3.2 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 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.
20
VLT Micro Drive Design Guide
Relative scalling reference
Input command:
preset ref bit0, bit1, bit2
Preset reference
±100%
Y
X
+
Parameter choise:
Reference resource 1,2,3
±200%
+
±200%
External reference in %
( )
Y
100
MG02K102 - VLT
Input command:
freeze reference
maxRefPCT
Relative
reference
=
±200%
X+X*Y/100
minRefPct
min-max ref
±100%
Freeze
reference &
increase/
decrease
reference
Input commands:
Speed up/speed down
®
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 %