Siemens SINAMICS G115D Operating Instructions Manual page 271

How does the converter calculate the load torque?
At low speeds, the converter calculates the load torque M
The calculation takes place under the following conditions:
• Speed ≥ p1226
• Acceleration setpoint < 8 1/s
• Acceleration × moment of inertia (r1493) < 0.9 × p1560
How does the converter calculate the moment of inertia?
For higher speed changes, the converter initially calculates the accelerating torque M
difference between the motor torque M
M = M
B
Moment of inertia J of the motor and load is obtained from the accelerating torque M
angular acceleration α (α = rate at which the speed changes):
J = M
SINAMICS G115D distributed drive
Operating Instructions, 12/2020, FW V4.7 SP13, A5E48681219B-002
- M - M
M L R
/ α
B
(≙ speed change 480 rpm per s)
2
, load torque M
M
Advanced commissioning
6.18 Motor control
from the actual motor torque.
L
and frictional torque M
L
as
B
:
R
and
B
269