Siemens SINAMICS G120C USS/MB - Moment of Inertia Estimator

6.19.3.5 Moment of inertia estimator
Background
From the load moment of inertia and the speed setpoint change, the inverter calculates the
accelerating torque required for the motor. Via the speed controller precontrol, the accelerating
torque specifies the main percentage of the torque setpoint. The speed controller corrects
inaccuracies in the precontrol (feed-forward control).
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Figure 6-54 Influence of the moment of inertia estimator on the speed control
The more precise the value of the moment of inertia in the inverter, the lower the overshoot
after speed changes.
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Figure 6-55 Influence of the moment of inertia on the speed
Function
From the actual speed, the actual motor torque and the frictional torque of the load, the inverter
calculates the total moment of inertia of the load and motor.
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Figure 6-56 Overview of the function of the moment of inertia estimator
Advanced commissioning
6.19 Motor control
SINAMICS G120C converter
276 Operating Instructions, 09/2017, FW V4.7 SP9, A5E34263257B AF