Siemens Sinamics G110M Original Instructions Manual page 195

Calculating the moment of inertia
If all of the following conditions are met, the inverter calculates the moment of inertia:
①
•
– The sign of M
– M
②
•
• The inverter has calculated the load torque in at least one direction of rotation.
• Acceleration setpoint > 8 1/s
③
The inverter calculates the load torque again after acceleration.
Moment of inertia precontrol
In applications where the motor predominantly operates with a constant speed, the inverter
can only infrequently calculate the moment of inertia using the function described above.
Moment of inertia precontrol is available for situations such as these. The moment of inertia
precontrol assumes that there is an approximately linear relationship between the moment of
inertia and the load torque.
SINAMICS G110M Operating Instructions
Operating Instructions, 04/2015, FW V4.7.3, A5E31298649B AD
The rated accelerating torque M
is the same as the direction of the actual acceleration
B
> p1560 × rated motor torque (r0333)
B
speed > p1755
For larger changes, the inverter initially cal-
culates the accelerating torque M
ence between the motor torque M
torque M
M = M
B
The moment of inertia J of the motor and
load is then obtained from the accelerating
torque M
(α = rate of change of speed):
J = M
B
must satisfy the following two conditions:
B
(≙ speed change 480 rpm per s)
2
8.6 Motor control
and frictional torque M
L
- M - M
M L R
– and the angular acceleration α
B
/ α
Functions
as differ-
B
, load
M
:
R
195