Rockwell Automation 20A PowerFlex 70EC/700VC - Manual (Page 65)

Position Indexer/Speed Profiler 61
Position Indexer/
Speed Profiler Overview
The profile/indexer may be configured as a velocity regulator or a position
regulator. If position control is desired, encoder feedback is required. Parameter
088, [Speed/Torque Mod] is used to select the “Pos/Spd Prof” mode. Sixteen steps
are available with this feature.
Common Guidelines for all step types
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.”
Limits - Many threshold values can affect the performance of the profile/indexer. To
help minimize the possibility of overshooting a position, ensure that the following
parameters are set for the best performance.
[Regen Power Limit] - default is –50% and will likely require a greater negative
value. A brake or other means of dissipating regenerative energy is
recommended.
[Current Lmt Sel] & [Current Lmt Value] - By default these parameters are set
to provide 150% of drive rating. If lowered, the performance may be degraded.
[Bus Reg Mode A] - The default setting will adjust frequency to regulate the DC
bus voltage under regenerative conditions. This will most likely cause a position
overshoot. To resolve this, select “Dynamic Brak” and size the load resistor for
the application.
[Bus Reg Mode B] - The default setting will adjust frequency to regulate the DC
bus voltage under regenerative conditions. This will most likely cause a position
overshoot. To resolve this, select “Dynamic Brak” and size the load resistor for
the application.
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.
Position Loop Tuning
Two parameters are available for tuning the position loop. [Pos Reg Filter],
parameter 718 is a low pass filter at the input of the position regulator. [Pos Reg
Gain], parameter 719 is a single adjustment for increasing or decreasing the
responsiveness of the regulator. By default these parameters are set at roughly a 6:1
ratio (filter = 25, gain = 4). It is recommended that a minimum ratio of 4:1 be
maintained.
Jogging
A jog function is compatible with profiling but the drive must be in a stopped
condition. If the drive is presently running a profile, the jog will be ignored. The
direction of the jog is controlled by the sign of the jog speed. This can be
manipulated via analog input scaling, from a network communication device or
with the HIM module.
70EC 700VC 700H
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