Parameterization Of The V/F Scalar Control - WEG CFW100 Programming Manual

9.1 PARAMETERIZATION OF THE V/f SCALAR CONTROL

The scalar control is the inverter factory default control mode for its popularity and because it meets most
applications of the market. However, parameter P202 allows the selection of other options for the control mode,
as per chapter 8 AVAILABLE MOTOR CONTROL TYPES on page
The V/f curve is completely adjustable in four different points as shown in
factory default set a curve pre-adjusted for motors 50 Hz or 60 Hz, as options for P204. This format, point P0
defines the amplitude applied at 0 Hz, while P2 defines the rated amplitude and frequency and beginning of field
weakening. Intermediate points P1 allow the setting of the curve for a non-linear relationship between torque and
frequency, for instance, in fans where the load torque is quadratic in relation to the frequency. The field weakening
region is determined between P2 and P3, where the amplitude is maintained in 100 %.
Output
voltage (%)
The factory default setting of the CFW100 defines a linear relation of the torque with the frequency by means of
three points (P , P and P ).
0 1 2
The points P [P136, 0 Hz], P
0
frequency relation imposed to the output approximates the ideal curve for the load. Therefore, for loads in which
the torque behavior is quadratic in relation to the frequency, such as in centrifugal pumps and fans, the points
of the curve can be set or the Quadratic V/f control mode can be used so as to save energy. This Quadratic V/f
curve is presented in Figure 9.3 on page
Output
voltage (%)
NOTE!
In frequencies below 0.1 Hz, the output PWM pulses are cut, except when the inverter is in DC
Braking mode.
P142
P143
P
1
P136
P
0
P146
Figure 9.2: Curve V/f
[P143, P146], P [P142, P145] and P
1 2
9-3.
P142
P136
Figure 9.3: Quadratic V/f Curve
Return
8-1.
Figure 9.2 on page
P P
2 3
P145 P134
[100 %, P134] can be set so that the voltage and
3
P145 P134
frequency (Hz)
Advance
V/f Scalar Control
9-3,although the
Output
Output
CFW100 | 9-3
9