Rockwell Automation 20D PowerFlex 700S with Phase I Control Reference Manual - Manual (Page 21)

Rockwell Automation Publication PFLEX-RM002D-EN-E - August 2013 21
Detail Drive Configuration and Operation Chapter 1
Technical Information
The bus regulator limits the maximum bus voltage for systems that do not have
(or have limited) braking or regenerative capabilities. The bus regulator limits the
bus voltage by comparing the DC bus voltage feedback to a DC bus voltage
reference. It then limits the regenerative power allowed back onto the DC bus to
keep the DC bus voltage at or below the reference value and prevent a “DC Bus
Overvolt” fault.
Dynamic braking uses a seventh insulated gate bipolar transistor (IGBT) and
braking resistor to dissipate regenerative energy. The drive switches the seventh
IGBT on and off to keep the DC bus voltage at or below the DC bus voltage
reference. Parameters in the PowerFlex 700S specify whether the resistor is an
internal or external resistor. For an external resistor, the user can program the
resistor specifications for protection of the resistor. Only resistors specifically
designed for pulse and high energy dissipation (dynamic braking) should be
used.
The PowerFlex 700S allows the user to select bus regulation, dynamic braking, or
a combination of bus regulation and dynamic braking.
Bus Regulator/Braking Configuration
Parameter 414 [Bus/Brake Cnfg] determines the configuration of bus regulation
and dynamic braking. Parameter 414 is broken down into the following bits:
Bus/Reg Brake Ref
Rated Volts
415
401
414 00
02
306
414 03
300
127
128
125
-1
123
124
DC Bus Voltage
Brake/Bus Confg
(Brake Enable)
(BusRef Hi/Lo)
100
Brake/Bus Cnfg
(Bus Reg En)
X
X
X
+
&
/
+
-
Bus Volt
Regulator
Limit 0.045
2
Motor Spd Fdbk
Mtring Power Lim
Regen Power Lim
Power
Limit Calc
+
Iq Actual Lim
Torque Neg Limit
Min
Max
Torque PosLim Actl
Torque NegLim Actl
Torque Pos Limit
126
353
Bit 0 - Brake Enable
When this bit is set to 1 it enables the internal brake transistor (seventh IGBT). When this bit is set to 0 then the
internal brake transistor is disabled.
Bit 1 - Brake Extern
When this bit is set to a 1 it configures the brake operation for an external resistor. Then the external brake resistor
protection is based on the peak watts entered into parameter 416 [Brake PulseWatts] and the continuous watts
entered in parameter 417 [Brake Watts]. When this bit is set to 0 it configures the brake operation for an internal
resistor. Then 416 [Brake PulseWatts] and 417 [Brake Watts] are not active.
Bit 2 - BusRef Hi/Lo
This bit configures whether bus regulation or dynamic braking turns on first. This bit is only active when parameter
414 [Bus/Brake Cnfg] bits 0 and 3 are both set to 1. When this bit is set to 1 the dynamic braking turns on first (at
the DC bus voltage set by parameter 415 [Bus Reg/Brake Ref]), and then the bus regulator turns on if the DC bus
voltage continues to rise (at the DC bus voltage set by 415 [Bus Reg/Brake Ref] plus 4.5%). When this bit is set to 0
the bus regulator turns on first (at the DC bus voltage set by 415 [Bus Reg/Brake Ref]) and then the dynamic
braking turns on when there are any transients above 415 [Bus Reg/Brake Ref].
Bit 3 - Bus Reg En
When this bit is set to 1, bus regulation is enabled. When this bit is set to 0, bus regulation is disabled.