Hitachi Powering Inverter Power Up Instructions page 2

Powering Inverters from DC
It is possible to power inverters from a DC Power source, or to connect the DC Bus of multiple inverters together to
achieve energy savings, since inverters in power driving mode can use power from those that are in regeneration mode.
[1] Connection method
There are several ways for DC bus connection of the inverters. (Examples of 3-phase 200V or 400V class inverter.)
Case 1 : Connected in parallel to a common DC bus
DC power
supply
INV #1
INV #2
INV #n
Case 3 : AC & DC Connected together
AC power
supply
+
-
Ø Advantage and disadvantages of each connection method.
Item
Œ
Connecting to + & - terminal
•
Connecting to AC inputs and - terminal
M 1
M 2
M n
INV #1
M 1
INV #2
M 2
INV #n
M n
Contents
Case 2 : Connected in parallel to an A-fed inverter
AC power
supply
+
-
DC supply connection methods
Œ
Connecting to + and - terminal
•
Connecting to AC inputs and - terminal
Advantage
Ÿ
No concern for the
rectifier bridge diodes.
Ÿ
Integrated inrush current
limiting circuit is used.
INV #1
INV #2
INV #n
INV
+
-
INV
+
-
Disadvantage
Ÿ
There will be no inrush
current limiting.
Ÿ
Rectifier bridge diodes
of the main inverter may
need to be up-sized.
M 1
M 2
M n
M
M