Rockwell Automation 2364P Parallel DC Bus Supply Config. - Manual (Page 20)

Publication 2364P-5.01 December 1999
1-8 Theory of Operation
The diagram below shows the NRU//RGU motoring bus voltage. The
RGUs regulate the bus voltage for the first 10% of the rated current
for the RGUs, then the NRUs supply current for the remainder of the
load (while the RGU current is limited to 10% of the RGU rating).
Figure 1.12
NRU//RGU Bus Voltage–Motoring
When the load is under 10% of the maximum motoring current, the
RGUs can regulate (or maintain) the bus voltage. The RGU (master
RGU) will evaluate the voltage on the bus, and will calculate the
current needed to maintain the bus voltage. If a regenerative current
is needed to maintain the voltage, the RGUs will begin switching
their IGBTs to regenerate current onto the AC line. The diodes in the
NRU will still not conduct current.
Figure 1.13
RGU Regenerating
% Load
DC
B
u
s V
o
lt
ag
e
10 0%
(T otal N R U ratin g +
10 % o f R GU ra tin g )
0 %
0 V D C
1.5 2 x V A C
10%
(of RG U ra tin g )
1.3 5 x V A C
1.52 x A C Lin e
V oltag e
R GU N R U
3-Ph as e
A C Lin e
C u rren t
(U p to 10 0% of th e
R GU ra tin g )
N o
Cu rre n t
v
V