Characteristics Of U/F Control - Siemens SINAMICS G120 Operating Instructions Manual
Low voltage inverters
built-in units with cu250s-2 control units and
encoder evaluation
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Also See for SINAMICS G120:
- List manual (1256 pages) ,
- Manual (732 pages) ,
- Operating instructions manual (550 pages)
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6.21.2.1
Characteristics of U/f control
The inverter has different V/f characteristics.
①
②
Figure 6-48
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.
The value of the output voltage at the rated motor frequency also depends on the following
variables:
● Ratio between the inverter size and the motor size
● Line voltage
Converter with the CU250S-2 Control Units
Operating Instructions, 04/2018, FW V4.7 SP10, A5E31759476B AG
The voltage boost of the characteristic optimizes the speed control at low speeds
With the flux current control (FCC), the inverter compensates for the voltage drop in the stator
resistor of the motor
Characteristics of V/f control
Advanced commissioning
6.21 Motor control
291
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