6.19.2.1 Characteristics of U/f control
The inverter has different V/f characteristics.
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① The voltage boost of the characteristic optimizes the speed control at low speeds
② With the flux current control (FCC), the inverter compensates for the voltage drop in the stator
resistor of the motor
Figure 6-47 Characteristics of V/f control
The inverter increases its output voltage to the maximum possible output voltage. The
maximum possible output voltage of the inverter depends on the line voltage.
When the maximum output voltage is reached, the inverter 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.
Advanced commissioning
6.19 Motor control
SINAMICS G120C converter
Operating Instructions, 09/2017, FW V4.7 SP9, A5E34263257B AF 261
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