Siemens SINAMICS G120D Operating Instructions Manual page 140

Setting functions
8.5 Motor control
Function when accelerating or braking
The moment of inertia estimator is active when both condition
①
•
②
•
determines the switchover between controlled and regulated operation of the encoderless
vector control.
③
Effect of the moment of inertia estimator
The moment of inertia estimator delivers its result to the pre-control of the speed controller
for calculating the acceleration torque.
Figure 8-17
140
The accelerating torque is greater than 10 % of the motor rating torque.
The speed is greater than p1755 (factory setting: 13.3 % of rated speed). P1755
After acceleration, load estimation is reactivated.
Effect of the moment of inertia estimator on the speed control
The motor torque M
M
torque M and the acceleration torque M
L
The moment of inertia estimator calculates the
moment of inertia J of the motor and load from
the acceleration torque M
acceleration α (α = rate of change of speed):
The motor torque M
M
torque M and the acceleration torque M
L
M = M - M
B M L
J = M / α
B
①
and condition
Converter with control units CU240D-2
Operating Instructions, 04/2014, FW V4.7, A5E34262100B AA
is the total of the load
.
B
and the angular
B
is the total of the load
.
B
②
are met: