Knee­shaped Acceleration Characteristic Curve; Adaptation To The Motor Characteristic Curve - Siemens SINUMERIK 828D Function Manual

4.2.20 Knee­shaped 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.
1: Torque decrease zone
n : Speed above which reduced torque has to be assumed
red
n : Maximum speed
max
M : Max. torque
max
M : Torque at n (corresponds to creep acceleration)
red max
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 =
can be used to select various types of characteristic curve:
0 = Constant characteristic
1 = Hyperbolic characteristic
2 = Linear characteristic
The following figures show typical velocity and acceleration characteristic curves for the respective types of
characteristic:
Constant characteristic
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
characteristic
B2: Acceleration
4.2 Functions
247