Siemens CU240S DP-F - Ramp-Function Generator

Functions
8.13 Setpoint channel
Control Units CU240S
Operating Instructions, 11/2006, A5E00766042B AA
8-61
8.13.2 Ramp-function generator
Data
P1120, P1121
r1119, r1170
Parameter range:
P1130 … P1142
Warnings: -
Faults: -
Function chart number: FP5000, FP5300
Description
The ramp-function generator (RFG) is used to limit the acceleration when the setpoint
changes according to a step function. This therefore helps to reduce the stressing on the
mechanical system of the machine. An acceleration ramp and a braking ramp can be set
independently of one another using the ramp-up time P1120 and the ramp-down time
P1121. This allows a controlled transition when the setpoint is changed (see figure below).
I
I
I
I
I
PD[
I

I

W
I
PD[
3 3


3333 W
W
XS
W
GRZQ
P1082
f
-
f
P1120
2
P1131P1130
t
12
up
⋅+
+
=
P1082
f
-
f
P1120)
2
1131P1130P
(
t
12
up
⋅+
+
=
P1120
2
P1131P1130
t
up
+
+
=
P1082
f
-
f
P1121
2
P1133P1132
t
12
down
⋅+
+
=
P1121
2
P1133P1132
t
down
+
+
=
P1120
2
P1131P1130
>
+
P1121
2
P1133p1132
>
+
P1082
f
-
f
P1121)
2
1133P1132P
(
t
12
down
⋅+
+
=
P1120
2
P1131P1130
≤
+
P1121
2
P1133P1132
≤
+
1082P
f
-
f
12
=
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IRU
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Figure 8-43 Ramp-function generator
In order to avoid torque surges at the transitions (constant velocity phase ←→
accelerating/braking phase), additional rounding-off times P1130 … P1133 can be