Characteristics Of U/F Control - Siemens SINAMICS G115D Operating Instructions Manual

7.20.2.1

Characteristics of U/f control

The converter has different U/f characteristics.
①
②
The converter increases its output voltage to the maximum possible output voltage. The
maximum possible output voltage of the converter depends on the line voltage.
When the maximum output voltage is reached, the converter only increases the output
frequency. At this point, the motor enters the field weakening range: At constant torque, the
slip decreases quadratically as the speed increases.
The value of the output voltage at the rated motor frequency also depends on the following
variables:
• Ratio between the converter size and the motor size
• Line voltage
SINAMICS G115D Wall Mounted distributed drive
Operating Instructions, 07/2023, FW V4.7 SP14, A5E52808211A AA
The voltage boost of the characteristic optimizes the speed control at low speeds
With the flux current control (FCC), the converter compensates for the voltage drop in the stator
resistor of the motor
Advanced commissioning
7.20 Motor control
285