Function diagrams (see sinamics s list manual) – Efficient Networks Siemens Sinamics S120 User Manual

Page 128

Vector control

4.6 Droop

Drive Functions

128

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Figure 4-10 Speed controller with droop

The droop function has a torque limiting effect on a drive that is mechanically coupled to a

different speed (e.g. guide roller on a goods train). In this way, a very effective load

distribution can also be realized in connection with the torque setpoint of a leading speed-

controlled drive. In contrast to torque control or load distribution with overriding and

limitation, with the appropriate setting, such a load distribution controls even a smooth

mechanical connection or the case of slipping.
This method is only suitable to a limited extent for drives that are accelerated and braked

with significant changes in speed.
The droop feedback is used, for example, in applications in which two or more motors are

connected mechanically or operate with a common shaft and fulfill the above requirements. It

limits the torque differences that can occur as a result of the mechanical connection between

the motors by modifying the speeds of the individual motors (drive is relieved when the

torque becomes too great).
Prerequisites
● All connected drives must be operated with vector control and speed control (with or

without an encoder).

● Only a single common ramp function generator may be used for mechanically coupled

drives.

Function diagrams (see SINAMICS S List Manual)

● 6030 Speed setpoint, droop, acceleration model