Rockwell Automation Publication 750-RM003A-EN-P - April 2018 75
Bus Supply Hardware and Parameter Conversion Chapter 2
PowerFlex 755TM Bus Supply Control
The PowerFlex 755TM bus supply excludes any standard or optional door-
mounted operator devices. Precharge normally occurs when the input
disconnect (FD1) is closed. When precharge is completed, the AC input MCB
circuit breaker (CB1) is closed automatically, but IGBT modulation does not
automatically begin. Line side converter manual IGBT modulation start/stop/
run functions must be controlled via hardwired digital I/O or through the
communication Logic Command Word. See publication 750-PM100
for
detailed parameter settings for controlling the line side converter.
When line-side converter modulation is stopped, the converter IGBT
transistors are disabled, however, diode rectifiers in the IGBT power devices
are active. In this case, there is DC bus voltage available even when IGBT
modulation is stopped but available DC output power is reduced. See monitor
file parameter 13: 28 [Derated Amps] to understand and monitor the line side
converter derating when IGBT modulation is stopped.
The PowerFlex 755TM bus supply power circuit configuration is
fundamentally different in design compared to the PowerFlex 700AFE bus
supply. Because of this difference, startup/shutdown methods for energizing
AC power, precharging, and controlling of IGBT modulation is through
different methods.
Table 38
outlines the differences in startup/shutdown and fault handling
between the bus supplies.
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