Siemens SINUMERIK 828D

B2: Acceleration
4.2 Functions
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
247
4.2.20 Kneeshaped acceleration characteristic curve
4.2.20.1 Adaptation to the motor characteristic curve
Function
Various types of motor, particularly stepper motors, have a torque characteristic that is highly dependent upon
speed and shows a steep decrease in torque in the upper speed range. To ensure optimum utilization of the
motor characteristic curve, it is necessary to reduce the acceleration once a certain speed is reached.
Figure 4-6 Torque characteristic curve of a motor with torque characteristic that is highly dependent upon speed
Simulation of torque characteristic
For the purpose of simulating the torque characteristic of the motor characteristic curve, the machine data:
MD35242 $MA_ACCEL_REDUCTION_TYPE =
characteristic
can be used to select various types of characteristic curve:
The following figures show typical velocity and acceleration characteristic curves for the respective types of
characteristic:
Constant characteristic
1: Torque decrease zone
n
red
: Speed above which reduced torque has to be assumed
n
max
: Maximum speed
M
max
: Max. torque
M
red
: Torque at n
max
(corresponds to creep acceleration)
0 = Constant characteristic
1 = Hyperbolic characteristic
2 = Linear characteristic

0
UHG
0>1P@


Q>@
Q
PD[
Q
UHG
0
PD[