Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 134)

134 Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013
Chapter 1 Detail Drive Configuration and Operation
Accel/Decel Ramp and S-Curve
The accel/decel ramp generator can be bypassed for certain functions. When
parameter 151 [Logic Command] bit 0 - “SpdRamp Dsbl” is on, the ramp is
bypassed. Otherwise, the reference is ramped according to the rates determined
by parameters 32 [Accel Time] and 33 [Decel Time]. For example, the ramp rate
for acceleration would be [Motor NP RPM]/[Accel Time]. The ramped
reference can be viewed in parameter 42 [Ramped Spd Ref ].
The drive can produce a linear ramp output or an s curve signal. The s curve is
used when [Logic Command] bit 1 - “Spd S Curve En” is on and the ramp is not
bypassed. Parameter 34 [S Curve Time] sets the time that the s curve will be
applied at the beginning and at the end of the ramp. Half of the time specified in
parameter 34 is added to the beginning of the ramp and half to the end of the
ramp (as shown in the example below). The result of the s curve block can be seen
in parameter 43 [S Curve Spd Ref ].
32
33
34
Inv
Logic
1 0
0 1
157 01
&
157 02
151 00
151 01
43 42
Ramp S Curve
Logic
1 0
0 1
S Curve Spd Ref Ramped Spd Ref
S Curve Time
Accel Time
Decel Time
Logic Command
(Spd S Crv En)
Logic Ctrl State
(SRef Ramp En)
Logic Ctrl State
(SRef SCrv En)
S Curve Time = 1.0 second
Speed
Time in Seconds
0.5 sec.
Accel Time = 5.0 seconds
Total Ramp Time = 6.0 seconds
0.5 sec.