Danfoss VLT AutomationDrive FC 301 Programming Manual page 98

Parameter Descriptions
If S-ramps are selected, set the level of non-linear jerk
compensation required. Set jerk compensation by defining
the proportion of ramp-up and ramp-down times where
acceleration and deceleration are variable (that is,
increasing or decreasing). The S-ramp acceleration and
deceleration settings are defined as a percentage of the
3 3
actual ramp time.
Speed
Ramp (X) S-Ramp
Ratio at Accel.End
Linear
Ramp (X)
S-Ramp
Ratio at
Accel.End
Illustration 3.26 Linear Ramping Times
3-40 Ramp 1 Type
Option:
[0] Linear
*
[1] S-ramp Const
Jerk
[2] S-ramp Const
Time
96
VLT
Ramp (X) S-Ramp
Ratio at Dec.End
Jerk compensated
Ramp (X)
Ramp (X)
Up Time
Down Time
Function:
NOTICE
If [1] S-ramp Const Jerk is
selected and the reference
during ramping is changed,
the ramp time may be
prolonged to realize a jerk-free
movement, which may result
in a longer start or stop time.
Extra adjustment of the S-
ramp ratios or switching
initiators may be necessary.
Select the ramp type, depending on
requirements for acceleration/
deceleration.
A linear ramp gives constant
acceleration during ramping. An S-
ramp gives non-linear acceleration,
compensating for jerk in the
application.
Acceleration with lowest possible
jerk.
S-ramp based on the values set in
parameter 3-41 Ramp 1 Ramp Up
Time and parameter 3-42 Ramp 1
Ramp Down Time.
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®
AutomationDrive FC 301/302
3-41 Ramp 1 Ramp Up Time
Range:
Size
related
*
Ramp (X)
S-Ramp
Ratio at
Dec.End
3-42 Ramp 1 Ramp Down Time
Range:
Size
related
*
3-45 Ramp 1 S-ramp Ratio at Accel. Start
Range:
50 %
*
3-46 Ramp 1 S-ramp Ratio at Accel. End
Range:
50 %
*
Function:
[ 0.01 - 3600 Enter the ramp-up time, that is the
s] acceleration time from 0 RPM to
the synchronous motor speed n
Select a ramp-up time which
prevents the output current from
exceeding the current limit in
parameter 4-18 Current Limit during
ramping. The value 0.00
corresponds to 0.01 s in speed
mode. See ramp-down time in
parameter 3-42 Ramp 1 Ramp Down
Time.
t s x n
acc
Par . 3 − 41 =
ref RPM
Function:
[ 0.01 - 3600 Enter the ramp-down time, that is
s] the deceleration time from the
synchronous motor speed n
RPM. Select a ramp-down time such
that no overvoltage occurs in the
inverter due to regenerative
operation of the motor, and such
that the generated current does not
exceed the current limit set in
parameter 4-18 Current Limit. The
value 0.00 corresponds to 0.01 s in
speed mode. See ramp-up time in
parameter 3-41 Ramp 1 Ramp Up
Time.
t s x n
dec
Par . 3 − 42 =
ref RPM
Function:
[ 1 - 99 %] Enter the proportion of the total
ramp-up time (parameter 3-41 Ramp
1 Ramp Up Time) in which the
acceleration torque increases. The
larger the percentage value, the
greater the jerk compensation
achieved, and thus the lower the
torque jerks occurring in the
application.
Function:
[ 1 - 99 %] Enter the proportion of the total
ramp-up time (parameter 3-41 Ramp
1 Ramp Up Time) in which the
acceleration torque decreases. The
larger the percentage value, the
greater the jerk compensation
.
S
RPM
s
to 0
s
RPM
s
M0013101