Rockwell Automation 20B PowerFlex 700 AC Drives Vector Control (v4.001 and up) - Manual (Page 124)

124 Rockwell Automation Publication 20B-UM002G-EN-P - July 2014
Appendix C Application Notes
Position Indexer/Speed
Profiler The PowerFlex 700 includes a position indexer/speed profiler which provides
either point-to-point positioning with a position regulator or speed profiling
using a velocity regulator. Point-to point positioning can be either incremental
moves or absolute moves which are referenced to home. Encoder feedback
(incremental encoder) is required for the position regulator. Speed profiling steps
can be time-based or triggered by digital inputs, encoder counts or parameter
levels. These speed profiling steps can be operated open loop or with an encoder.
The indexer is programmed by entering data into a 16 step array. Each step has
several variables for optimal customization (see below). The steps can be run in a
continuous cycle or a single cycle. The process can also move to or from any step
in the array.
This feature also includes homing capability to a limit switch or a marker pulse
using an automatic homing procedure.
Common Guidelines for all Step Types
• Enabling Position Indexer/Speed Profiler
This feature is enabled by selecting “7, Pos/Spd Prof ” in [Speed/Torque
Mod], parameter 088. Parameters 700…877 set up the indexer/profiler.
• Motor Control Modes
For Position Indexing with an encoder, only FVC Vector Control should
be used for optimum performance.
For Velocity Profiling, any motor control mode can be used. However,
Sensorless Vector or FVC Vector Control modes will offer the best
performance.
• Direction Control
The drive must be configured to allow the profile to control the direction.
This is accomplished by setting [Direction Mode], parameter 190 to
“Bipolar” (default is “Unipolar”).
• Speed Regulator
The bandwidth of the speed regulator will affect the performance. If the
connected inertia is relatively high, the bandwidth will be low and
therefore a bit sluggish. When programming the acceleration and
deceleration rates for each step, do not make them too aggressive or the
regulator will be limited and therefore overshoot the desired position.
Step Type Value Velocity Accel
Time Decel
Time Next Step
Condition Dwell Batch Next
IMPORTANT The PowerFlex 700 uses an incremental encoder only. Since absolute encoders
are not used, your process must be able to accommodate this homing
procedure after a power down or power loss.