Allen-Bradley PowerFlex 70 Reference Manual

Speed/Torque Select 2-177
Speed/Torque Select [Speed/Torque Mod] is used to choose the operating mode for
the drive. The drive can be programmed to operate as a velocity regulator, a
torque regulator, or a combination of the two. Refer to 2.36
.
Figure 2.36
As shown, [Speed/Torque Mod] (parameter 88) is used to select the mode of
operation. Zero torque current is allowed when set to “0.”
When set to a “1,” the drive/motor is operated in speed mode. The torque
command changes as needed to maintain the desired speed.
A value of “2” selects torque mode. In torque regulation mode, the drive
controls the desired motor torque. The motor speed will be a result of the
torque command and load present at the motor shaft.
Min and Max mode are selected by values 3 and 4, respectively. These two
modes offer a combination of speed and torque operation. The algebraic
minimum or maximum of speed/torque will be the operating point for the
Min and Max modes. The drive will automatically switch from speed to
torque mode (or from torque to speed) based on the dynamics of the motor/
load.
The Min mode is typically used with positive torque and forward speed
operation, the minimum of the two being closest to zero. The Max mode is
opposite, typically used with reverse speed and negative torque, the
maximum being the least negative (closest to zero).
Sum mode is selected when set to “5.” This mode allows an external torque
command to be added to the speed regulator output when desired.
Speed Regulation Mode
Operating as a speed regulator is the most common and therefore simplest
mode to setup. Examples of speed regulated applications are blowers,
conveyors, feeders, pumps, saws, and tools.
In a speed regulated application, the torque reference is generated by the
speed regulator output. Note that under steady state conditions the speed
feedback is steady while the torque reference is a constantly adjusting
signal. This is required to maintain the desired speed. At transient state, the
torque reference will change dramatically to compensate for a speed
change. A short duration change in speed is the result of increasing or
decreasing the load very rapidly.
Vector
FV
431
Scale
Scale
433
432
429
428
434
430
0
0
1
2
3
4
5
6
/
x
+
Ref A Hi
Ref A Lo
Ref B Hi
Torq Ref A Div
Speed/Torque Mod
Spd Reg PI Out
Torq Ref B Mult
Ref B Lo
Torque Ref B Sel
427
Torque Ref A Sel
88
Min
Max
+
abs
Min

Allen-Bradley PowerFlex 70 Specifications

General

Brand	Allen-Bradley
Model	PowerFlex 70
Category	Controller
Language	English