Siemens SINAMICS G150 Operating Instructions Manual page 571

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.
You can configure the moment of inertia precontrol via p5310.
● Using bit 0, you can activate the calculation of the characteristic (p5312 ... p5315).
● Using bit 1, you can activate the moment of inertia precontrol.
The following bit combinations are possible:
p5310.0 = 0,
p5310.1 = 0
p5310.0 = 0,
p5310.1 = 1
p5310.0 = 1,
p5310.1 = 0
p5310.0 = 1,
p5310.1 = 1
The status word of the moment of inertia precontrol is indicated in r5311.
Example
For a horizontal conveyor, in a first approximation, the moment of inertia depends on the load.
Figure 9-26
The relationship between load torque and torque is saved in the inverter as linear
characteristic.
● In positive direction of rotation:
Moment of inertia J = p5312 x load torque M
● In negative direction of rotation:
Moment of inertia J = p5314 x load torque M
You have the following options to determine the characteristic:
● You already know the characteristic from other measurements. In this case, you must set
the parameters to known values when commissioning the system.
● The inverter iteratively determines the characteristic by performing measurements while
the motor is operational.
Converter cabinet units
Operating Instructions, 07/2016, A5E03347396A
Moment of inertia precontrol not active
Cyclic calculation of the coefficients without moment of inertia pre-
control (commissioning)
Moment of inertia precontrol activated (without cyclic calculation of
the coefficients)
Moment of inertia precontrol activated (with cyclic calculation of the
coefficients)
Relationship between moment of inertia J and load torque M
Functions, monitoring, and protective functions
L
+ p5313
L
+ p5315
L
9.3 Extended functions
571