Siemens SINAMICS S120 Function Manual page 79

Standard RFG tracking
If the load torque exceeds the torque limit of the drive and so causes the actual speed to
diminish, the ramp-function generator output is not tracked to the actual speed value. If the
torque limit is overshot during the ramp-up because the ramp-up time was selected too small,
the effective ramp-up time of the ramp-function generator lengthens.
Result: Once the load torque decreases, the drive accelerates again at the current limit to the
setpoint. The ramp-up is stopped when the torque, power or current limit is reached. p1145 can
be used to set the permitted following error. The speed setpoint is so tracked to the set
permitted following error. The acceleration ramp is flattened. If the torque decreases, the ramp-
up continues on the speed setpoint with a flattened ramp to the torque/current limit.
n
act
n
RFG
n-setpoint
t t
1
Figure 4-11 Standard RFG tracking
At the times t
torque M
For t
additional torque prevents the further acceleration of the motor to the rated speed on the ramp-
function generator ramp.
The ramp-function generator output is tracked to the actual speed value when p1145 > 1 which
causes a flattening of the rise ramp for the decrease of M
ramp at the current/torque limit to the speed setpoint (t
For t
additional torque causes the drive to be braked to standstill.
For t
tracked to the actual speed value, the drive now accelerates at the torque/current limit to the
speed setpoint.
Extended RFG tracking
The extended ramp-function generator tracking returns the ramp-function generator output to
the actual speed value when the drive reaches the torque limit. Consequently, the drive does
not return to the current limit but rather back on the set acceleration ramp to the original
setpoint.
Drive functions
Function Manual, 06/2019, 6SL3097-5AB00-0BP2
t
2 3
and t , an overload torque M
1 3
. The torque limit of the drive is exceeded.
L
the drive is being ramped up along specified ramp-function generator ramp. The
1
, the drive runs with the specified speed setpoint and is already in field weakening. The
3
, the torque reduces again to M
4
M
Overload torque
UEL
M
Load torque
L
t
4
starts to act on the drive in addition to the load
Ovl
. The drive accelerates with flattened
Ovl
).
2
. Because the ramp-function generator output is not
L
Extended setpoint channel
4.5 Ramp-function generator
M
UEL
M
L
t
77