Rockwell Automation 7000L PowerFlex Medium Voltage AC Drive (C Frame) - Classic Control - Manual (Page 312)

5-4 Functional Description
7000L-UM300I-EN-P – June 2013 7000 “C” Frame
Speed Command (cont.)
Three skip speeds Skip Speed 1(50), Skip Speed 2 (51), Skip Speed 3
(52) are provided to prevent the drive from continuously operating at
a certain speed. This feature is sometimes needed to avoid
mechanical vibrations occurring in a drive system at certain speeds.
The skip speed zone around each Skip Speed is specified by the
parameter Skip Spd Band1 (53), Skip Spd Band2 (54), Skip Spd
Band3 (55) If the desired Speed Command lies in a given skip speed
zone, the Speed Command is clamped to the lowest value in the
zone. E.g. if Skip Speed 1 is 45 Hz with Skip Spd Band1 as 1 Hz,
then the skip speed range extends from 44.5Hz to 45.5Hz. If the
desired speed command is set to 45 Hz, then the drive will avoid this
speed and run at 44.5Hz.
The final stage in processing the command is the whether the drive
has been requested to run forward or reverse. The sign is changed if
reverse rotation is selected or is set to zero if there is no run request.
Speed Reference
The function of the Speed Reference block is to determine the Speed
Reference (278) from the desired Speed Command (277). PF7000
provides two options:

S-curve

Linear Ramp
To select, S-curve a non-zero value of S-curve Percent (475) is
selected. Using parameter S curve Acc1 (481), the drive
automatically calculates the linear and the non-linear portions of the
S-curve as shown in Figure 5.2. Following example shows how to
use S-curve parameters:
Example
If S curve Acc1 is set for 20sec with 20% in S-curve Percent, then
the total acceleration time is increased by 0.2 x 20 = 4 seconds. The
total acceleration time will now be 24 seconds with 4 seconds in the
non-linear portion of the S-curve. Since the curve is symmetrical,
each of the segments will be of 2 seconds duration.
The parameters for deceleration are calculated using parameter S
curve Dec1 (479) and S-curve Percent (475) and shown in Figure 5.2.
Linear Ramp is enabled if the S-curve Percent is set to zero.
Independent four section ramps are provided for acceleration and
deceleration. The ramp is specified by 4 Ramp Speeds, 4 Accel and
Decel times and is shown in Figure 5.3.