Siemens SINAMICS S150 NEMA, Руководство по эксплуатации

Страница: 632 / 862

Functions, monitoring and protective functions
9.4 Extended functions
Enclosed Drives
630
Operating Instructions, 12/2018, A5E36652151A
Figure 9-31 Calculating the moment of inertia
The moment of inertia J of the motor and load is then obtained from the accelerating torque
M
B
and the angular acceleration α
J = M
B
/ α
The following conditions must be fulfilled for this calculation:
①
The rated acceleration torque M
B
must satisfy the following two conditions:
•
M
B
must be greater than p1560 x r0333 (rated motor torque).
• M
B
must be greater than 80% of the friction torque (0.4 x (p1563 - p1564)).
②
For operation without encoder, the speed must be > p1755 (in closed-loop controlled
operation).
③
The converter calculates the load torque again after acceleration.
If the load estimation has taken place and the moment of inertia does not settle (stabilize)
(r1407.24/26 = 0), then increasing the acceleration (p2572/p2573) is recommended.
If the load moment of inertia is significantly greater than the motor moment of inertia, then
the transient event can also be improved via parameterization of the load moment of inertia
(p1498).
Moment of inertia precontrol
In applications where the motor predominantly operates with a constant speed, the converter
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.