Rockwell Automation Publication 750-AT006D-EN-P - January 2022 25
Chapter 1 Background
For additional illustration of the control, see the PowerFlex 755 Control Block Diagrams in the PowerFlex Drives with TotalFORCE Control
Programming Manual, publication 750-PM100.
Torque Loop
The torque loop is active in position, velocity, and torque control modes. In Position mode, the position, velocity, and torque loops are
enabled. In Velocity mode, the velocity and torque loops are enabled. Here, the torque loop consists of the highlighted elements that are
shown in Figure 23
.
Figure 23 - Torque Loop
In torque mode, the torque loop is enabled and the position and velocity loops are replaced by a torque reference command. Here, the torque
loop consists of the highlighted elements that are shown in Figure 24
.
Figure 24 - Torque Reference
Table 6 - Acceleration Feed Forward Parameters
Parameter No. Parameter Name Description
10:1972 [Accel FF Mode]
Enables this feature and
selects possible velocity
reference sources
Disabled (0) Disables the function
Int Ramp Ref (1)
• Selects the internal ramp for the source.
• The internal ramp is generated from the rate of change of 10:1925 [VRef Filtered], the
typical setting that is used for inertia compensation on a standalone drive.
Ext Ramp Ref (2)
• Selects the external ramp reference for the source. This reference comes from
10:1978 [Ext Ramped Ref]
• This setting is available for applications that supply a ramped speed reference
external to the drive. For example, when the velocity ramp is generated in a Logix
Controller.
Spd Rate Ref (3)
• Selects the Feed Forward Velocity Rate for the source. This rate comes from
10:1931 [FF Vel Rate Ref].
• This selection is also used with an externally supplied ramp rate.
10:1973 [c Accel FF Gain]
A calculated gain that is applied as K
AFF
in the drive during acceleration when 10:905 [System C/U Select] = Calculated (0).
10:1974 [u Accel FF Gain]
Applied as K
AFF
in the drive during acceleration when 10:905 [System C/U Select] = User Entered (1).
10:1975 [Accel FF GainNeg]
Applied as K
AFF
in the drive during deceleration.
10:2070 [Accel FF Output]
Displays the inertia compensation output in [rev/sec
2
].
10:1978 [Ext Ramped Ref]
Used when 10:1972 [Accel FF Mode] = Ext Ramp Ref (2). Send a value to this parameter from an external controller to generate the
Acceleration Feedforward signal. It is meant for an external motor speed ramp input signal and is entered in units of Hz or rpm,
depending on the value of 10:1891 [Velocity Units].
2
1
sJ
T
PI
s
PI
s
Fs
K
T
P
REG
V
REG
Velocity
Feedback
Filter
Position
Feedback
Velocity
Estimate
Feed
Forwards
Kvff Kaff
Position
Command
LP
LL
N
Torque Loop Filters
Load Torque
Load
Observer
K
J
Torque
Estimate
Adaptive
Tuning
RN
System Under Control
P
REF
2
1
sJ
T
K
T
LP
LL
N
Torque Loop Filters
Load Torque
System Under Control
T
REF
Adaptive
Tuning
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