Functions
8.24 Open-loop and closed-loop control
Control Units CU240S
Operating Instructions, 11/2006, A5E00766042B AA
8-163
8.24.1.1 Voltage boost
Data
P1310 … P1312 Parameter range:
r0056 bit 05
Warnings: -
Faults: -
Function chart number: FP6100
Description
For low output frequencies, the V/f characteristics only output a low output voltage. Even at
low frequencies, the ohmic resistances of the stator winding play a role, which are neglected
when determining the motor flux in V/f control. This means that the output voltage can be too
low in order to:
● implement the magnetization of an induction motor,
● to hold the load
● to equalize losses (ohmic losses in the winding resistances) in the system or
● to provide a breakaway/accelerating/braking torque.
The output voltage can be increased (boosted) in the SINAMICS G120 using the parameters
as shown in the table below.
Note
Especially at low frequencies, the motor temperature is additionally increased as a result of
the voltage boost (the motor overheats)!
The voltage value at 0 Hz is determined from the product of rated motor current P0305,
stator resistance P0350 and the appropriate parameters P1310 … P1312.
Using very high boost values may cause the motor to stuck at a low frequency due to the
Imaxcontroller (very high boost may cause overcurrent failure).
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