Rockwell Automation SB3000 AC Power Modules - Manual (Page 65)

Theory of Operation C-1
A
PPENDIX
C
Theory of Operation
C.1 Typical SB3000 System
SB3000 Power Modules are used to supply regulated common DC bus power to one
or more SA3000/SA3100 Power Modules. As illustrated in figure C.1, a typical
SB3000 system is made up of the following:
• an AC power disconnect device with overcurrent protection
• a soft-charge assembly which consists of pre-charge resistors and a pre-charge
contactor
• an AC line filter reactor
• a power bridge
• a regulator consisting of both hardware and software elements.
The power distribution cabinet is mounted separately from the SB3000 Power Module
and typically contains the AC power disconnect/overcurrent protection device, the
soft-charge assembly, and the AC line filter reactor.
The AC line filter reactor is an energy storage element that isolates the converter
bridge. This reactor limits the current flow between the AC line and the DC bus while
providing a voltage boost between the input AC voltage and the output DC voltage.
The pre-charge resistors provide for controlled soft-charging of the DC bus capacitors
to an initial voltage from which the SB3000 regulator can be safely started.
The SB3000 power bridges are the same three-phase IGBT inverter bridges that are
used in the High Power SA3000 Power Modules, but are connected such that the
three-phase AC leads are connected to the AC line, instead of to a motor, and the DC
leads are connected as an output to a DC bus designed to feed one or more
SA3000/SA3100 Power Modules.
The regulator controls the operation of all the elements in the system and links the
SB3000 Power Module to the application level.