WEG CFW300 V1.3X, Programming Manual

Page: 67 / 157

V/f Scalar Control
CFW300 | 9-5
9
P142 - Maximum Output Voltage
P143 - Intermediate Output Voltage
Adjustable
Range:
0.0 to 100.0 %
Factory
Setting:
P142 = 100.0 %
P143 = 50.0 %
Properties: cfg, V/f
Description:
These parameters allow adjusting the inverter V/f curve together with its orderly pairs P145 and P146.
P145 - Field Weakening Start Frequency
P146 - Intermediate Output Frequency
Adjustable
Range:
0.0 to 400.0 Hz Factory
Setting:
P145 = 60.0
(50.0) Hz
P146 = 30.0
(25.0) Hz
Properties: cfg, V/f
Description:
These parameters allow adjusting the inverter V/f curve together with its orderly pairs P142 and P143.
The V/f curve can be adjusted in applications where the motor rated voltage is smaller than the power supply
voltage, for example, a power supply of 220 V with motor of 200 V.
The adjustment of the V/f curve is necessary when the motor has a frequency different from 50 Hz or 60 Hz,
or when a quadratic approximation is desired for energy saving in centrifugal pumps and fans, or in special
applications: when a transformer is used between the inverter and the motor or the inverter is used as a power
supply.
P137 - Automatic Torque Boost
Adjustable
Range:
0.0 to 30.0 % Factory
Setting:
0.0 %
Properties:
V/f
Description:
The automatic torque boost compensates the voltage drop in the stator resistance because of active current.
Look at
Figure 9.1 on page 9-2 , where variable m
IxR
corresponds to the automatic torque boost action on the
modulation index defined by V/f curve.
P137 actuates similarly to P136, but the value set is applied proportionally to the output active current in relation
to the maximum current (2 x P295).
The setting criteria of P137 are the same as those of P136, that is, set the value as low as possible for the motor
start and operation at low frequencies, because values above those increase the losses, heating and overload
of the motor and inverter.
The block diagram of Figure 9.6 on page 9-6 shows the automatic compensation action IxR responsible for
the increment of the voltage in the ramp output according to the increase of the active current.