WEG CFW100 Programming Manual page 54

Another condition that prevents the output voltage from reaching its maximum value is internal losses of the inverter.
Such losses are associated to the dead time of the switching and losses in the components, being aggravated by
the increase of the switching frequency.
Such conditions, variations in the DC Link voltage and internal losses can be compensated with variations in the
modulation index; however, with specific characteristics as presented in each of the options below:
P149 = 0 (Disabled): The DC link compensation is disabled. The DC link voltage oscillations will reflected in the
output voltage.
P149 = 1 (Standard): In this mode, the output voltage will be generated according to the ideal V/f profile,
parameterized in P142, P143, P145 and P146, but not reaching the maximum available voltage at the output
and also not generating distortions in the output voltage.
P149 = 2 (Overmodulation): When selecting this option the output voltage will also be generated according to
the ideal V/f profile, parameterized in P142, P143, P145 and P146, but the maximum available voltage can be
generated. On the other hand, distortions in the output voltage may occur.
P149 = 3 (Extended): This option works similarly to option 2 (overmodulation). However, in the event of a DC
link voltage drop of approximately 20 % of the rated voltage, the function may take two different actions:
1. If the torque demand is low, it reduces the voltage applied to the motor, also reducing the motor current,
allowing to maintain the application, or;
2. If the torque demand is high, it reduces the output frequency until it is possible to generate a voltage according
to the V/f profile.
Both cases have restrictions of use according to the final application, and the user is responsible for validating the
application.
✓
NOTE!
It is recommended to use extended DC link voltage compensation mode (P149 = 3) for quadratic
torque applications (blowers, fans, pumps and compressors).
WARNING!
!
The use of the DC link voltage compensation options does not compensates for all internal losses of
the inverter, and it is not intended to increase the performance in installations that do not observe the
recommendations in the product user's manual.
P151 - DC Link Regul. Level
Range: 325 to 810 V
Properties: V/f, VVW
Description:
Voltage level to activate the DC link voltage regulation.
Table 8.1: Actuation Level of the voltage regulation
Input Voltage P151 Actuation Band
100 to 127 Vac 391 to 460 Vdc
200 to 240 Vac 349 to 410 Vdc
380 Vac 621 to 781 Vdc
415 Vac 646 to 781 Vdc
440 Vac 716 to 781 Vdc
480 Vac 747 to 781 Vdc
P151 (factory default)
430 Vdc
380 Vdc
781 Vdc
781 Vdc
781 Vdc
781 Vdc
Micro Mini Drives | 8-5
MOTOR CONTROL
8