Rockwell Automation 20G PowerFlex 750-Series AC Drives - Manual (Page 46)

46 Rockwell Automation Publication 750-RM002B-EN-P - September 2013
Chapter 1 Drive Configuration
Option 1 “Adjust Freq”
If [Bus Reg Mode
n] is set to 1 “Adjust Freq” The Bus Voltage Regulator is
enabled. The Bus Voltage Regulator setpoint follows “Bus Reg Curve 1” below a
DC Bus Memory of 650V DC and follows the “DB Turn On” above a DC Bus
Memory of 650V DC (
Table 5 ). For example, with a DC Bus Memory at 684V
DC, the adjust frequency setpoint is 750V DC.
Below you can see the DC bus is being regulated as the speed is sacrificed to be
sure the drive does not trip on over voltage.
Figure 3 - PowerFlex 750-Series Bus Regulation – Adjust Frequency
Option 2 “Dynamic Brak”
If [Bus Reg Mode
n] is set to 2 “Dynamic Brak” The Dynamic Brake Regulator is
enabled. In Dynamic Brake mode the Bus Voltage Regulator is turned off. The
“DB Turn On” and turn off curves apply. For example, with a DC Bus Memory at
684V DC, the Dynamic Brake Regulator turns on at 750V DC and turns back
off at 742V DC. The Dynamic Brake mode can operate differently depending
upon the setting of P382 [DB Resistor Type] either External or Internal.
900
800
700
600
500
400
300
200
100
0
12
10
8
6
4
2
0
-1 0 1 2 3 4 5 6 7 8 9
DC Bus Voltage Speed Feedback
DC bus is regulated under the over voltage trip point.
Motor stops in just under 7 seconds instead
of the programmed 1 second decel.
Seconds
DC B
us
V
olt
s
10
V
olt
s =
B
ase
Sp
ee
d