Siemens SINAMICS G120D Series User Manual

Advanced commissioning
7.5 Motor control
7.5.2.6
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).
Figure 7-25 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.
Figure 7-26 Influence of the moment of inertia estimator 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.
Figure 7-27 Overview of the function of the moment of inertia estimator
Converter with control units CU240D-2
Operating Instructions, 04/2015, FW V4.7.3, A5E34262100B AB
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Siemens SINAMICS G120D Series Specifications

General

Brand	Siemens
Model	SINAMICS G120D Series
Category	Media Converter
Language	English