Rockwell Automation 20B PowerFlex 70, PowerFlex 700 Reference Manual - Manual (Page 57)

Bus Regulation
Rockwell Automation Publication PFLEX-RM001H-EN-P - June 2013 57
The bus voltage regulation set point (Vreg) in the drive is fixed for each voltage
class of drive. The bus voltage regulation set points are identical to the internal
dynamic brake regulation set points VDB's.
To avoid over-voltage faults, a bus voltage regulator is incorporated as part of the
acceleration/deceleration control. As the bus voltage begins to approach the bus
voltage regulation point (Vreg), the bus voltage regulator increases the
magnitude of the output frequency and voltage to reduce the bus voltage. The
bus voltage regulator function takes precedence over the other two functions. See
Figure 13 .
The bus voltage regulator is shown in the lower one-third of Figure 13 . The
inputs to the bus voltage regulator are the bus voltage, the bus voltage regulation
set point Vreg, proportional gain, integral gain, and derivative gain. The gains are
intended to be internal values and not parameters. These will be test points that
are not visible to the user. Bus voltage regulation is selected by the user in the Bus
Reg Mode parameter.
Operation
Bus voltage regulation begins when the bus voltage exceeds the bus voltage
regulation set point Vreg and the switches shown in
Figure 13 move to the
positions shown in Table 2 .
Table 2 Switch Positions for Bus Regulator Active
SW 1 SW 2 SW 3 SW 4 SW 5
Bus Regulation Limit Bus Reg Open Closed Don’t Care
DB Bus
Motor Speed
Output Frequency