Rockwell Automation 20D PowerFlex 700S AC Drives with Phase II Control Programming Manual - Manual (Page 107)

Rockwell Automation Publication 20D-PM001C-EN-P - July 2013 107
Programming and Parameters Chapter 2
No. Name
Description Values
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755 Posit Offset Spd
Sets the speed of position offset. A position offset command will not exceed this speed. The actual speed of
offset is limited to a maximum value of 1/(inertia x pos gain) so as not to cause a torque pulse greater than 1 per
unit. The speed will change exponentially.
Default:
Min/Max:
Units:
Scale: 176.4000
-/+14112.0000
rpm
Par 4 [Motor NP RPM] = 1.0 P.U.
Y RW Real
756 X Offst SpdFilt
Displays the output of a first order filter whose time response is shaped specifically to provide an output that
represents the actual speed of offset correction. It may be used as a feed forward into speed reference to secure
minimal position error during changes to offset.
Default:
Min/Max:
Units:
Scale: 0.0000
-/+14112.0000
rpm
Par 4 [Motor NP RPM] = 1.0 P.U.
RO Real
757 Abs Posit Offset
Provides an offset to absolute position. Setting Par 740 [Position Control], bit 8 “Xzero Preset” presets Par 744
[PositRef EGR Out], Par 747 [Position Cmmd], Par 763 [Position Actual] and Par 765 [Posit Actl Load] with the
value in Par 762 [Position Fdbk] minus Par 757 [Abs Posit Offset] upon drive enable.
Default:
Min/Max: 0
-/+2147483648 Y RW 32-bit
Integer
758 Pt-Pt Posit Ref
Provides position reference to the point to point position regulator, when the value in Par 742 [Position Ref Sel]
= 2 “Pt to Pt”. The initial value is latched upon position enable without causing movement. Subsequent changes
to reference are relative to the latched position unless the position is re-referenced by
Par 740 [Position Control],
bit 10 “Pt-Pt ReRef”. Position moves may be made within the limits of plus or minus 31 bits. Point-to-point
reference may be changed, and even reversed, during a move.
Default:
Min/Max: 0
-/+2147483648 Y RW 32-bit
Integer
759 Pt-Pt Accel Time
Acceleration time (sec) to base speed, active only in point to point mode. Acceleration to a relatively low speed
may be exponential.
Default:
Min/Max:
Units: 10.0000
0.1000/6553.5000
s Y RW Real
760 Pt-Pt Decel Time
Deceleration time (sec) from base speed to zero, active only in point to point mode. Some tailing can be expected
at the end of a move as the drive comes into command position. It is left to the user to select a time that does not
place the drive in current or torque limit. Deceleration from relatively low speed may be exponential.
Default:
Min/Max:
Units: 10.0000
0.1000/6553.5000
s Y RW Real
761 Pt-Pt Filt BW
Sets the bandwidth of a low pass filter which affects smoothness at the start of deceleration in the point to point
mode. A high filter bandwidth will produce a more square deceleration torque, one with a higher level of jerk.
Typical values range from 5 to 100 (rad/sec). A zero value will bypass the filter. Tail-out is influenced mainly by
Par 768 [Posit Reg P Gain].
Default:
Min/Max:
Units: 25.0000
0.0000/500.0000
rad/s Y RW Real
762 Position Fdbk
Displays the accumulated pulse count of the selected position feedback. Select a position feedback device with
Par 777 [PositionFdbk Sel].
Default:
Min/Max: 0
-/+2147483648 RO 32-bit
Integer
763 Position Actual
Displays the accumulated motor position as a 32-bit integer. It tracks Par 762 [Position Fdbk]. When the position
regulator is not enabled, this parameter is initialized to Par 762 [Position Fdbk] or to the selected position
reference as determined by
Par 740 [Position Control], bit 6 “AbsPositCtrl”.
Default:
Min/Max: 0
-/+2147483648 RO 32-bit
Integer
764 Posit Load Fdbk
Tracks the load position, as a 32-bit integer. When a gear box connects the load to the motor, Par 766 [Posit FB
EGR Mul] and Par 767 [Posit FB EGR Div] must be set to account for the gear ratio. Set Par 766 [Posit FB EGR Mul]
equal to Par 767 [Posit FB EGR Div] if the load is directly connected to the motor.
Default:
Min/Max: 0
-/+2147483648 Y RW 32-bit
Integer
765 Posit Actl Load
Holds the accumulated output of the Load Gear Ratio as a 32-bit integer and forms the primary feedback for the
position regulator integral channel. It is very important that the load gear ratio be precisely set such that the
delta pulse count of one motor revolution equals the delta pulse count of this parameter. When the position
regulator is not enabled, this parameter is initialized to
Par 762 [Position Fdbk] or to the selected position
reference as determined by Par 740 [Position Control], bit 6 “AbsPositCtrl”.
Default:
Mi/Max: 0
-/+2147483648 RO 32-bit
Integer
766 Posit FB EGR Mul
A 32-bit integer in the numerator of the load EGR function. It is multiplied by Par 764 [Posit Load Fdbk] and
divided by Par 767 [Posit FB EGR Div] to reflect the load pulse count to the motor (effectively removing the gear
box ratio). The accumulated position values Par 763 [Position Actual] and Par 765 [Posit Actl Load] will be equal
if the ratio is set properly. There may be some difference due to lost motion in the gear train, but there should
not be an accumulated difference. It is often necessary to count gear teeth as gear box manufacturers often
approximate exact ratios with decimal numbers. Enter a negative value in the numerator to account for reversed
motor rotation.
Default:
Min/Max: 1
-/+1000000 Y RW 32-bit
Integer
767 Posit FB EGR Div
This is a 32-bit integer that forms the denominator of the load EGR function.
Default:
Min/Max: 1
1/2000000 RW 32-bit
Integer
768 PositReg P Gain
Sets position regulator gain as measured from position error to speed reference. The gain number is identically
equal to position regulator bandwidth in rad/sec. For example: A gain of 10 means that a per unit position error
of 0.1 sec. will effect a 1.0 P.U. speed change (1 per unit position error is the distance traveled in 1 sec. at base
motor speed). The maximum value of this parameter is typically 1/3 of the speed bandwidth (rad/sec) but may
be set considerably higher with careful tuning of the speed regulator output lead/lag filter.
Default:
Min/Max:
Units: 4.0000
0.0000/200.0000
rad/s Y RW Real
769 Position Error
Actual position error in motor pulse counts. When the position regulator is not enabled, this 32-bit integer
register is initialized to zero. When the position regulator is enabled, this parameter contains the running value
of position error, often referred to as “following error”.
Default:
Min/Max: 0
-/+2147483648 RO 32-bit
Integer