Bus Regulation 2-27
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 2.2.
The bus voltage regulator is shown in the lower one-third of Figure 2.2. 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 2.2 move to the
positions shown in
Table 2.D.
Table 2.D 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
Output
Motor
Ch1
Ch3
Single Seq 2.50kS/s
100mV
500mV
Ch2 100mV M 200ms Ch3 1.49
V
3
2
1
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