B2: Acceleration
4.2 Functions
Basic Functions
Function Manual, 09/2011, 6FC5397-0BP40-2BA0
247
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.
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
0UHG
0>1P@
Q>@
QPD[
QUHG
0PD[
