Commissioning
5–6
1070 066 028-101 (01.05) GB
5.1.4
V/f characteristic
The V/f characteristic serves to adjust the frequency inverter to the motor.
The shape of the characteristic is determined by the input of the rated motor
data. Furthermore, the type of characteristic and the information on
I
x R
compensation must be selected.
D
Up to the rated motor frequency the power output rises. Above the
rated frequency it remains constant while there is a
!P
f
falling torque
characteristic.
D
The maximum output voltage corresponding to the rated motor voltage
is adjusted independent of braking or acceleration processes of other
axes connected to the link. Thus, the motor power is optimally used.
D
In the case of linear-type characteristics with torque boost the motor
shows an improved starting behavior.
The output voltage is raised depending on the motor load.
D
Using the
I
x R compensation, the starting behavior of the motor is
further improved if the torque boost is insufficient or has not been
activated.
This improvement is achieved by raising the output frequency in the
lower speed range up to the
I
x R starting-motor cut-out frequency.
output
frequency
f
output voltage
V
P02
P08
P07
P10
P09
field weakening range
rated voltage
P06
max.
output frequency
rated
frequency
I
x R starting-motor
cut-out frequency
I
x R
comp.
.
A standard characteristic for a standard motor has been set in the
factory.